Revision of Dadagulella gen. nov., the “Gulella radius group” (Gastropoda: Streptaxidae) of the eastern Afrotropics, including six new species and three new subspecies

The genus Dadagulella gen. nov. is described to include 16 species of small, dentate, ovateacuminate Afrotropical snails. An identifi cation key is provided and biogeography, anatomy and systematics are discussed. The type species is the Kenyan D. radius (Preston, 1910) comb. nov., whose name has informally been used for part of the group in the past. Substantial intraspecifi c variation occurs in three species: D. radius itself, D. browni (van Bruggen, 1969) comb. nov. and D. minuscula (Morelet, 1877) comb. nov. (= Ennea fi scheriana Morelet, 1881) (non Gulella minuscula Emberton & Pearce, 2000) . We recognise subspecies within each of these: D.radius radius (Preston, 1910) comb. nov., D. r. calva (Connolly, 1922) comb. et stat. nov., D. browni browni (van Bruggen, 1969) comb. nov., D. b. mafi ensis subsp. nov., D. b. semulikiensis subsp. nov., D. minuscula minuscula (Morelet, 1877) comb. nov., D. m. mahorana subsp. nov. Six new Tanzanian species are described: D. cresswelli sp. nov., D. delta sp. nov., D. ecclesiola sp. nov., D. frontierarum sp. nov., D. minareta sp. nov., and D. pembensis sp. nov. The genus includes seven other previously described species: D. cuspidata (Verdcourt, 1962) comb. nov.; D. rondoensis (Verdcourt, 1994) comb. nov.; D. conoidea (Verdcourt, 1996) comb. nov.; D. selene (van Bruggen & Van Goethem, 1999) comb. nov.; D. meredithae (van Bruggen, 2000) comb. nov.; D. nictitans (Rowson & Lange, 2007) comb. nov.; and D. delgada (Muratov, 2010) comb. nov.


Introduction
The Streptaxidae J. Gray, 1860, or "hunter snails" (Herbert & Kilburn 2004) are the most speciose terrestrial mollusc family in the Afrotropics.One group of small, ribbed, ovate-acuminate streptaxids, usually with a pointed apex and with characteristic apertural dentition, constitutes a distinctive part of the eastern Afrotropical fauna.They are litter-dwellers in lowland and montane forest and other well-vegetated habitats and can be locally common (e.g.van Bruggen & Appleton 1977;Rowson et al. 2010b).The species are among those currently included in Gulella L. Pfeiffer, 1856, an extremely large whorl was used as a measure of sculpture because the front of the body whorl was often calloused or eroded smooth.A spire angle was measured as the angle enclosed by a pair of lines beginning at the ends of the upper suture of the penultimate whorl and meeting at the shell apex.
A note on terminology is required.Our preferred term for the overall shell shape of the majority of species, where the maximum width is reached at approximately the middle of the shell (e.g.all of  is 'ovate-acuminate' (after van Bruggen & Van Goethem 1999;van Bruggen 2000;Muratov 2010, etc.).In nearly all species of the group the spire is substantially tapered towards the apex.The spire has itself usually been referred to as 'acuminate' (e.g.Preston 1910;Verdcourt 1962;van Bruggen & Van Goethem 1997;Muratov 2010).The sides of the upper whorls of the spire appear concave in a number of species (e.g.Figs 29-31) for which our preferred term is 'coeloconoid'.Where the upper whorls of the spire appear convex we use the term 'cyrtoconoid'.The apex of the shell, i.e. that part of the spire formed by the embryonic whorls, is pointed in most species, sharply in some.In others it is rounded at a macroscopic scale (any point is of course actually rounded at the most microscopic of scales).This variation appears to be at least partly independent of the spire angle, e.g.Figs 33-34 have a similar spire angle but very different apices.
For dimensions, see Table 1.
(known from three species) bearing multicuspid teeth, the outer cusps much smaller than the inner.Other anatomy (known from six species): salivary gland bilobed or Y-shaped.Vas deferens thickened or with diverticulum prior to insertion on penis, penis lacking sheath, with a muscular apex in which is embedded a spatulate scoop with a microscopically serrated tip, usually associated with one or two large apical hooks, and a few (<40) smaller hooks lower down.For dimensions, see Table 1.

Etymology
Prefix from Swahili noun "dada" meaning sister, with reference to the apparent relationships and East African centre of diversity of the group.

Description
Shell .Small to medium-sized relative to species of Gulella (2.3-5.5 mm high x 1.4-2.8mm wide), of 4.5-8 whorls.Ovate to ovate-acuminate (maximum width being approximately at middle of shell, usually at penultimate whorl) or subconical (maximum width being in bottom third of the shell, at body whorl).Spire characteristically narrowly to broadly acuminate, occasionally coeloconoid or cyrtoconoid (spire angle 43-77°), angle varying a little within most species.Apex (i.e.top of spire) pointed in most species, but rounded in others.Sutures usually deep, shells never completely smoothsided.Umbilicus closed or narrowly open, this sometimes varying within a species.Embryonic whorls usually smoothly granulate, with fine radial striae in two species, or irregularly punctate in another.The last part of the embryonic shell is sculptured with very fine radial striae in most (possibly all) species but these are worn away in all but the freshest individuals.Later whorls never smooth, with radial ribs (5-27 per mm on penultimate whorl) running from suture to suture, often strong and/or sinuous, lamella-like in some species.Peristome complete, or incomplete parietally, always reflected to some extent.Outer palatal surface of aperture with a depression, sometimes furrow-like, corresponding to the palatal tooth, and sometimes another corresponding to the basal tooth.Dentition 3-fold (rarely, and debatably, 2-fold) to 8-fold.Dentition consisting of at least one parietal tooth and one palatal tooth, the latter often slablike and/or bifid, sometimes forming a parieto-palatal sinus.Usually also with one deep-set columellar baffle, folded or sub-bifid or sub-trifid in some species.Often with additional parietal, palatal, basal and/or columellar teeth or denticles.Dentition is variable in some species but the form, as well as the number, of the teeth is often consistent enough to distinguish species.Juvenile shells (known from 7-8 species) always with 3-fold to 4-fold apertural dentition  except in one species, D. nictitans comb.nov., where the only known juvenile has no teeth.In several species, some or all of the teeth in juvenile shells appear to be resorbed at intervals.
Cephalopodium.Pale cream or yellow, usually with apricot-coloured to orange tentacle retractors and sometimes with brown speckles on the mantle.
pallial Complex.Sigmurethrous, with long zone of contact between long, oblong kidney and hindgut, pulmonary cavity not strongly vascularised.
Salivary glandS .United, soft, not tumid, elongate, bilobed to Y-shaped; each duct leaving at the apex of the lobe and evenly thick throughout.
BuCCal maSS.Very small and elongate, radula correspondingly small, tightly enrolled and difficult to locate or prepare. radula

Comparison and remarks
See General Discussion.

Type material examined
KENYA: lectotype (here designated) MRAC.I17592: 1 ad., "Shimbi Hills, British East Africa", standing as "radius", labelled "ex Putzeys-Musée, 1935", "type" and apparently the shell figured in Preston (1910: pl. VII, fig. 8).Verdcourt (1985) wrote that a second shell from Shimbi in the NHMUK type collection could not be located at that time.We too failed to trace this specimen.Van Bruggen (1969) referred to two other NHMUK shells from Gazi as "paratypes", presumably because they were labelled as such.However, Gazi (4.42°S, 39.50°E) is around 30 km from the type locality of Shimbi (Shimba) Hills (4.25 o S, 39.38 o E), and Preston (1910) distinguished between the two localities elsewhere in his paper.Thus it cannot be assumed that Gazi material has type status.

Description
Shell (Figs 1-5, 9-20, 43-50, 52-53).Very variable in size, shape and dentition, small to large (2.80-4.60 mm high x 1.60-2.44mm wide), of 6.0-7.0 whorls.Ovate-acuminate, spire narrowly to broadly acuminate (spire angle 55-70°).Apex pointed.Embryonic whorls smoothly granulate.Later whorls with relatively coarse and few ribs (7-16 per mm on penultimate whorl).Sutures relatively deep.Umbilicus closed or narrowly open.Peristome complete or (more often) incomplete parietally.Outer palatal surface of aperture with a depression corresponding to the palatal tooth and sometimes another one corresponding to the basal tooth.Dentition 5-fold to 7-fold, consisting of at least: one lamella-like parietal tooth; one slab-like palatal tooth, often bifid ; one basal denticle; one shallow columellar denticle (very weak in some cases) and one deep-set columellar baffle, always visible.Parieto-palatal sinus, if present, broad, seldom narrow or parallel-sided.Neither the columellar baffle nor basal denticle were mentioned in Preston's (1910) original description, although both are clearly visible on the lectotype which is apparently the originally figured specimen.We assume this to have been a lapsus.One or two additional columellar denticles may be present (e.g.Figs 12,14,15).Juvenile shells (Figs 43-45) with 3-fold dentition: one parietal lamella; one bifid basal tooth; and one columellar tooth or thickening.Some earlier teeth are retained in some juveniles and even adults (e.g.some specimens from Jozani).
Cephalopodium.Pale cream or yellow, with apricot to orange tentacle retractors and often with brown speckles on the mantle.
Salivary glandS (Fig. 69).United, soft, not tumid, elongate, bilobed to nearly Y-shaped; each duct leaving at the whitened apex of the lobe and evenly thick throughout.radula (Fig. 65).With a unicuspid central tooth and around 13 laterals in each half-row, diminishing gradually in size laterally.All laterals bicuspid or tricuspid, with outer cusps much smaller than inner cusps.
genitalia (Figs 73,77,83).Vas deferens appearing thickened prior to insertion on penis but actually with a short, broad parallel diverticulum.Penial sheath absent but with a thin sheath-like layer contiguous with walls of lower penis.Interior of penis with weak radial pilasters and small rhombic pads, sometimes with a longitudinal pilaster or short, rounded and weakly chitinized lobe.Apical, muscular part of penis with a single large hook, associated with a "scoop" with microscopically serrated tip.Elsewhere in penis, a single longitudinal row of short, simple hooks mounted on rhombic pads."Spermatophore" (see Discussion) present in penis and vagina of one Amboni specimen; "spermatophore" tail, apparently attached to penis wall, present in penis of one Pugu specimen.

Range and habitat
Eastern Kenya and eastern Tanzania, including Unguja (Zanzibar) island.Apparently replaced by other Dadagulella gen.nov.species on Pemba island and in some lowland areas and montane forests, and by D. browni comb.nov.s.l. in Tanzania from around 7.8°S southwards.Dadagulella r. radius comb.nov. is sympatric with other Dadagulella gen.nov.species at Kwamgumi, Pugu and Kimboza [it has also been recorded from Kimboza by Verdcourt (2006: 48)].The records are mainly from forest and other wellvegetated habitats; Verdcourt (2000) suggested the habitat was "woodland/forest".Lange & Mwinzi (2003) found D. radius comb.nov.across several forest types at Arabuko-Sokoke, but Ndalila (2011) found only three specimens in the Shimba Hills, all in scrub and grassland rather than forest.

Remarks
This appears to be the most widespread and variable species of Dadagulella gen.nov.In this we concur with van Bruggen (1969) and Verdcourt (1985) that D. radius comb.nov. is a species variable enough to include shells as different as the lectotype (Figs [1][2][3][4][5]11) and those from Diani Beach (Fig. 14).We retain one such extreme form, subsequently described by Connolly (1922) as Gulella calva Connolly, 1922, as a subspecies of D. radius comb.nov.(see below) but we refrain from describing additional subspecies since these forms are not obviously geographically isolated (e.g. at Amboni, Fig. 15) and occur throughout the geographical range of the species.The variation between them often appears continuous rather than discrete (e.g.compare , each from a similar latitude and arranged in order from W to E).Furthermore, some variability is often present at a single locality, e.g. at Gazi (compare Figs 12 and 13).Despite this, D. radius comb.nov.s.l.differs from other similar, lowland species as follows.It differs from D. browni comb.nov.s.l. in never having either an additional parietal denticle or two basal denticles, and in normally having a broader (or no) parieto-palatal sinus.It differs from D. delgada (Muratov, 2010) comb. nov. in lacking the flaring, lamella-like ribs and nearly always having a more broadly acuminate spire.It differs from D. ecclesiola sp.nov. in not having the basal denticle hidden behind the palatal tooth, in having at least one shallow columellar tooth, and in having a broader (or no) parieto-palatal sinus.The distinction between D. radius comb.nov.s.l. and D. minuscula comb.nov. of the Comoros, with which it was compared by Preston (1910), is discussed under the latter species.(Connolly, 1922) comb. et stat. nov. Figs 6-8, 51, 84; Table 1 Gulella calva Connolly, 1922: 495, pl. XIV, fig. 35. Gulella calva -Verdcourt 1962: 17;1983: 234. -Richardson 1988: 62. -Verdcourt 2000: 215;2006: 49.?"Gulella radius (Preston) var.(K, Mrima Hill Forest)" -Verdcourt 1962: 22.

Range and habitat
Lowlands of extreme southeastern Kenya, including Taru Desert.This subspecies has also been recorded from Malindi (Verdcourt 1962: 17) and Mrima Hill (4.48°S, 39.25°E) (Verdcourt 2006).Verdcourt (2000) suggested the habitat was "bushland to forest", in contrast to "woodland/forest" for D. r. radius comb.nov.Shells of both D. r. radius comb.nov.and D. r. calva comb.et stat.nov.have been found in river debris near Mombasa, but may have been washed in from different localities.

Remarks
The lectotype and similar material of this subspecies (Figs 6-8, 51) differ from D. r. radius comb.nov. in the more widely spaced ribs, more columnar shape and simpler dentition, although some specimens seem to show intermediate characters.Verdcourt evidently had difficulty separating them.Although Verdcourt (1962: 17) suggested G. calva was "scarcely more than a variety of G. radius", it keyed out in a separate part of his key, with radius appearing in two other places (1962: 13, 22).The second of these (p.22) was listed as "Gulella radius (Preston) var.(K [Kenya], Mrima Hill Forest)".Verdcourt's measurements, description, and range of apertural tooth formulas allow attribution of this taxon to D. r. calva comb.et stat.nov..In his later checklists, Verdcourt (1983: 234;2006: 48-49) maintained the two as separate species, and gave Mrima Hill as a locality for calva but not radius.He also kept them apart in his list of coastal molluscs (2000).Thus it appears likely that he later decided that (1962: 22) "radius var." belonged to what we treat as D. r. calva comb.et stat.nov.and not to what we treat as D. r. radius comb.nov.It also appears that he decided not to separate the two taxa.We too found this a difficult decision to take, owing to the morphological, habitat and distributional differences, which may of course be interrelated.To acknowledge this difficulty, and the potential difficulties in assigning future material to either, we rank calva as a subspecies of radius.
Cephalopodium.Pale cream, with pink-orange tentacle retractors and a few purple-brown speckles in the mantle.
radula.Described and figured by Aiken (1981) as having a unicuspid, 'heart-shaped' central tooth and nine laterals in each half-row, of which at least the inner six are tricuspid, diminishing gradually in size laterally.The outer cusps of most teeth are smaller than the inner cusp.According to Aiken (1981) the teeth are flexible when pressed by a cover slip and there are 47 rows.
genitalia (Figs 74,82).Upper parts of spermoviduct not recovered.Vas deferens appearing thickened prior to insertion on penis but actually with a very short, broad parallel diverticulum.Penial sheath absent.Interior of penis with weak radial pilasters.Apical, muscular part of penis with a single large hook, associated with a spatulate "scoop" with microscopically serrated tip.Elsewhere in penis, a single longitudinal row of short, simple hooks.

Remarks
We agree with van Bruggen (1969)

Range and habitat
Evergreen coastal thicket at the type locality.

Remarks
This taxon is in some respects intermediate between the type specimens of

Range and habitat
Lowland Guineo-Congolian forest at the type locality in the valley of the Albertine Rift.

Remarks
This subspecies is very similar to D. b. browni comb.nov.and, if found together, the two might not at first glance be distinguished.

Other material examined
None.

Range and habitat
At the type locality, vegetation on coral rag (Muratov 2010: 284).

Remarks
The few, flaring, lamella-like ribs and elongate, narrowly acuminate spire of D. delgada comb.nov.allow it to be separated from other species, including some D. radius comb.nov.s.l. which it resembles in size and dentition.
A basal denticle is also present, presumably in all specimens, but is partly or completely hidden by the palatal tooth which occludes much of the aperture.The denticle is visible when the shell is turned to the right (Fig. 56).Juvenile shells not known with certainty: an individual from Kimboza (Fig. 49), with dentition like that of a juvenile D. r. radius comb.nov., might belong to this species.Anatomy unknown.

Range and habitat
In forest at the type locality in the eastern Tanzanian lowlands.

Remarks
This species has much simpler dentition than D. minareta sp.nov.(which also occurs at Kimboza), and is usually smaller, with straight rather than sinuous ribs.Its dentition is more like that of D. r. radius comb.nov.(which again also occurs at Kimboza; Fig.

Range and habitat
Forest at the type locality in northern Tanzania.The vegetation is presumably of a montane type, since the crater floor is above 1700 m while the rim rises to over 2400 m or higher.

Remarks
This species is distinctive in its deep, long furrow on the outer palatal surface in combination with the coeloconoid spire and dentition.D. minerata sp.nov. shares these features, but differs in having weaker ribs and less complex dentition.It is the only Dadagulella gen.nov.species thus far collected in the volcanic (as opposed to block-faulted) highlands of Tanzania or Kenya.

Type material examined
Cephalopodium.Pale yellow, with apricot tentacle retractors.
Salivary glandS.United, soft, not tumid, elongate, Y-shaped; each duct leaving at the apex of the lobe and evenly thick throughout.
genitalia.Vas deferens thickened prior to insertion on penis but apparently without diverticulum.Penial sheath absent but with a thin sheath-like layer contiguous with wall of lower penis.Interior of penis with weak radial pilasters and small rhombic pads.Apical part of penis with a broad "scoop" with microscopically serrated tip, but without large hook.Elsewhere in penis a single longitudinal row of short, simple hooks mounted on rhombic pads.

Range and habitat
In forest at the type locality and in Pugu Hills Nature Reserve, both in the eastern Tanzanian lowlands, and in lowland forest on Mt.Kanga in the Nguru Mts.

Remarks
The dentition, most noticeably the squared-off shallow columellar tooth that runs in to connect with the baffle, readily distinguishes this species from D. ecclesiola sp.nov.(which also occurs at Kimboza) and D. r. radius comb.nov.(which also occurs at both Kimboza and Pugu).It also distinguishes it from D. cuspidata (Verdcourt, 1962) comb.nov., with which it shares the strong upper columellar tooth and fine regular radial striae on the embryonic whorls.It differs from D. cresswelli sp.nov., with which it shares the furrow-like depression on the outer palatal surface, in dentition and in having stronger ribs.
Dadagulella cuspidata (Verdcourt, 1962)  Outer palatal surface of aperture with a furrow-like depression corresponding to the upper palatal tooth.Dentition 6-fold (alternatively recognisable as 5-fold), consisting of: one lamella-like parietal tooth; two palatal teeth, the upper much larger and forming a parieto-palatal sinus; one basal, in-running tooth; and a strong, squarish columellar tooth, running in to form a columellar baffle which is connected to it.Juvenile shells and anatomy unknown.

Range and habitat
Elevation not stated but probably between 1500-2000 m at the type locality in northeastern Tanzania.

Remarks
This species differs from D. minareta sp.nov. in having two palatal teeth, in having a basal tooth, in the shape of the parietal tooth, and in size.
Salivary glandS (Fig. 70).United, soft, not tumid, elongate, Y-shaped; each duct leaving at the apex of the lobe and evenly thick throughout.
radula .With a unicuspid central tooth and around 15 laterals in each half-row, gradually diminishing in size laterally.All laterals bicuspid, tricuspid, or quadricuspid, with outer cusps much smaller than inner cusps.Teeth delicate, short and flake-like at the ventral end of the radular ribbon.
genitalia (Figs 75,79,80).Vas deferens appearing thickened prior to insertion on penis, but actually with a short, broad parallel diverticulum.Penial sheath absent but with a thin sheath-like layer contiguous with wall of lower penis.Interior of penis with weak radial pilasters and small rhombic pads.Apical, muscular part of penis with a single large hook, associated with a spatulate "scoop" with microscopically serrated tip.Elsewhere in penis, one or two longitudinal rows of short, simple hooks mounted on rhombic pads."Spermatophore" (see Discussion) present in penis of two Ngezi specimens; partially digested remains in bursa of another.

Range and habitat
Pemba Island, Tanzania, where widespread in forest and other vegetated habitats.

Remarks
This species was discussed by Rowson et al. (2010b), who suggested a thorough revision of the group to establish whether the Pemba populations were part of a variable D. radius comb.nov.or a subspecies or species endemic to Pemba.This uncertainty was incorporated into their conclusions on endemism on the island (Rowson et al. 2010b: 28-29, 32).We find here that there is little or no overlap with D. radius comb.nov.s.l. or other species, so conclude that this is an island endemic, which we here name D. pembensis sp.nov.Like specimens of D. r. radius comb.nov. on the opposite mainland at Amboni (e.g.Figs 15,53), D. pembensis sp.nov. is large and has a complex pattern of 6-fold dentition.However it is distinguishable from them by its even larger size, shallower sutures, and having on average an extra 0.5 whorls.It differs from D. minuscula mahorana subsp.nov.which has similar dentition, in its larger size, shallower sutures, and stronger and more widely spaced ribs.

Other material examined
None.

Description
Shell (Fig. 33).Medium-sized (3.60-3.90mm high x 2.00-2.20 mm wide), of 5.5 whorls.Ovateacuminate, although spire (spire angle 64-69°) less acuminate than in other Dadagulella gen.nov.Apex rounded.Embryonic whorls smoothly granulate.Later whorls with relatively coarse ribs (13-15 per mm on penultimate whorl).Sutures of intermediate depth.Umbilicus closed or nearly so.Peristome complete.Outer palatal surface of aperture with a long, furrow-like depression corresponding to the palatal tooth.Dentition 5-fold or 6-fold, consisting of: one V-shaped parietal tooth; one slab-like palatal tooth, forming a conspicuous and narrow parieto-palatal sinus; and two to three shallow columellar teeth, the lower the largest.A deep set-columellar baffle is partly or completely hidden by the constricted aperture, while a basal denticle is completely hidden behind the palatal tooth.However, the baffle and basal denticle are probably present in all specimens.One broken juvenile shell is known; it appears to lack teeth.
Salivary glandS.United, soft, not tumid, elongate, Y-shaped; each duct leaving at the apex of the lobe and evenly thick throughout.
genitalia.Figured in Rowson & Lange (2007).Vas deferens thickened prior to insertion on penis but apparently without diverticulum.Penial sheath absent.Interior of penis with weak radial pilasters, a single longitudinal pilaster, and small rhombic pads.Apical, muscular part of penis with two large hooks, associated with a spatulate "scoop" with microscopically serrated tip.Elsewhere in penis a single longitudinal row of short, simple hooks mounted on rhombic pads.

Range and habitat
Montane forest (1400-1900 m) at the type locality and three other Forest Reserves in the Taita Hills, southeastern Kenya (Rowson & Lange 2007).

Remarks
This species is included in Dadagulella gen.nov. on the basis of the apical penial scoop and hooks, and the Y-shaped salivary gland.

Other material examined
None.

Description
Shell (Figs 34,61).Medium-sized (3.15-3.40Outer palatal surface of aperture with a depression corresponding to the lower palatal teeth.Dentition 6-fold, consisting of: one complex, V-shaped and flaring parietal tooth; three palatal teeth, the lower two larger and set low down on the palatal surface, not forming a parieto-palatal sinus; one basal, in-running denticle; and one shallow but strong, in-running columellar tooth.Shells and anatomy of juveniles unknown.

Range and habitat
Submontane forest (970 m elevation) in the East Usambara Mountains, northeastern Tanzania.

Remarks
The complex dentition and detached peristome of D. frontierarum sp.nov.are unlike that of any other Dadagulella gen.nov.species.It is also characteristic for its few whorls, few ribs and sharply pointed apex.Biogeographically a close relationship with other species in and around the East Usambaras would seem likely but there is no strong resemblance.

Etymology
From Greek 'delta', after the letter we originally used as an informal morphospecies name for the species; used as a noun in apposition.Umbilicus narrowly open.Peristome incomplete parietally.Outer palatal surface of aperture with a depression corresponding to the palatal tooth.Dentition weak, 3-fold (although could be interpreted as 2-fold or 4-fold), consisting of: one lamella-like parietal tooth; one weak palatal tooth, not forming a parieto-palatal sinus; a columellar baffle so deeply set as to be almost invisible in apertural view; and a very weak shallow columellar swelling.Juvenile shells unknown.

Type material examined
Cephalopodium.Pale cream, with pale tentacle retractors.
genitalia (Figs 76,81).Vas deferens appearing thickened prior to insertion on penis but actually with an elongate, parallel diverticulum.Penial sheath absent.Interior of penis with weak radial pilasters and small rhombic pads.Apical part of penis with a single large hook, associated with a spatulate "scoop" with microscopically serrated tip.Elsewhere in penis, an elongate cluster of short, simple hooks mounted on rhombic pads.

Range and habitat
Montane forest (1000-1200 m) in the Udzungwa Mountains, central Tanzania.

Remarks
This species is distinctive in its simple and weak dentition, weaker than in any other Dadagulella gen.nov.species except in D. rondoensis (Verdcourt, 1994) comb. nov. andD. conoidea (Verdcourt, 1996) comb.nov.which have a more conical shape.It can be distinguished from Gulella udzungwensis van Bruggen, 2003, which also occurs on Mt.Mwanihana (van Bruggen 2003), by having a more acuminate spire and more pointed apex, deeper sutures, sinuous ribs and no basal tooth.

Other material examined
None.
Outer palatal surface of aperture with a depression corresponding to the palatal tooth.Dentition 5-fold, consisting of: one lamella-like parietal tooth; one bifid slab-like palatal tooth, not forming a parietopalatal sinus; a baso-columellar tooth or denticle; a deep-set columellar baffle and a shallower columellar tooth.Dentition alternatively recognisable as 6-fold, if the bifid palatal tooth is interpreted as two teeth ( van Bruggen 1969).Juvenile shells and anatomy unknown.

Range and habitat
Montane forest (1000-2720 m) in the Albertine Rift.The type locality and the other in the Virunga National Park are in bamboo forest ( van Bruggen & Van Goethem 1999).Wronski & Hausdorf (2010) also record it from montane forest at around 2300 m in Echuya Forest Reserve, southwestern Uganda.
Remarks Van Bruggen & Van Goethem (1999) considered this species to belong to the group of species among which van Bruggen (1969)

Other material examined
None.
Umbilicus closed or nearly so.Peristome incomplete parietally.Outer palatal surface of aperture with a depression corresponding to the palatal tooth.Dentition 3-fold to 4-fold, consisting of at least: one lamella-like parietal tooth; one slab-like palatal tooth, not forming a parieto-palatal sinus; and a mammillate columellar baffle.Additional teeth limited to a shallow, weak columellar swelling.Juvenile shells with 2-fold to 3-fold dentition: one parietal tooth; one columellar tooth; and usually one basal tooth (termed labral by van Bruggen 2000).Van Bruggen (2000) showed that earlier sets of dentition are visible through the shells of some transparent juveniles, even in the preceding whorls, suggesting slow or no resorbtion.Anatomy unknown.

Range and habitat
Montane forest (above 1500 m to around 2450 m) in northern and central Malawi, and adjacent part of Zambia (Chowo Forest).Van Bruggen (2000) suspected it to range into parts of Tanzania adjoining northern Malawi.

Remarks
This species is distinctive in its small size, very fine, numerous ribs, and dentition.It differs from D. radius comb.nov.s.l. and D. browni comb.nov.s.l. in the lack of a basal tooth or denticle.The apex is rounded in the holotype but more conical in paratypes figured by van Bruggen (2000).

Range and habitat
Nzwani (Anjouan) island in the Comoros archipelago; habitat unknown.

Remarks
Morelet (1877) described this species from Anjouan (type locality implied by the paper's title) under the name "Pupa minuscula" but figured it under the name "Pupa fischeriana" (pl.XII, fig.5).In the paper he compared it to three species from "Île Bourbon" (Réunion), but none is very like it, suggesting Morelet was unaware of other Dadagulella gen.nov.species and probably meaning that D. m. minuscula comb.nov.was the first species of the group to be collected.Two of the Réunion species are streptaxids of the Mascarene genus Gonospira Swainson, 1840 while the third belongs to the Pupillidae Turton, 1831 (see Griffiths & Florens 2006).Although Kobelt (1905Kobelt ( , 1910) ) Van Bruggen (1986) took a similar approach with two other streptaxids, one described by Preston from the Shimba Hills, the other by Morelet from Mayotte.
There is a nomenclatural issue concerning the name minuscula Morelet, 1877.Morelet (1881) tried to replace the name used for the (1877) description, Pupa minuscula, with the name used for the (1877) figure, Ennea fischeriana.Morelet (1881) wrote that the name P. minuscula had been published in error.Subsequently both Tryon (1885: 100) and Kobelt (1905: 166;1910: 158) accepted fischeriana as the species name.However, when revising the fauna of the Comoros, Fischer-Piette & Vukadinovic (1974) disagreed.They treated E. fischeriana is an objective synonym of P. minuscula since the latter was not preoccupied and was validly introduced.This point of view was followed by Richardson (1988).As a consequence, the lectotype of D. m. minuscula comb.nov. in NHMUK also becomes the lectotype of E. fischeriana and the latter name remains unavailable for a taxon founded on another specimen.This includes the paralectotype, which is further discussed below.

Range and habitat
Mayotte; habitat unknown.

Remarks
This Mayotte subspecies is here separated from its counterpart on Nzwani for the first time.Specimens of Dadagulella gen.nov.species from Mayotte were first discussed by Morelet (1881) under his proposed replacement name for Pupa minuscula (see above).He noted specimens from Mayotte were larger and had more complex dentition than those from Anjouan.Tryon (1885) and Kobelt (1905) followed Morelet in treating D. fischeriana (i.e.D. minuscula comb.nov.s.l.) as a variable species that was present on the "Comoros Islands" (Tryon 1885) or on Anjouan, with a "grössere Form auf Mayotte" (Kobelt 1905, although his dimensions of 9 mm x 2 mm must be erroneous).Both authors appear to have copied Morelet's (1877) figure of the lectotype of D. m. minuscula comb.nov., unless they saw material very like it, and appear to have repeated (translated) Morelet's (1881) comments on dentition.Tryon (1885) says "sometimes the parietal lamina is accompanied by a more profound very small tooth" but this may be a misinterpretation of Morelet's (1881) "le pli pariétal peut être accompagné d'une très petite denticule plus profonde", with "plus profonde" meaning 'deeper', rather than 'profound', i.e.
'more obvious' or 'more important'.Morelet's "denticule" is likely to refer to the bifid shape of the parietal tooth, rather than to an additional parietal denticle (like that of D. browni comb.nov.s.l.) which is not present in any of the specimens of D. minuscula comb.nov.s.l.we examined.It is not clear to which of the other teeth Morelet's (1881) "cinquième petite dent, dans la gorge de la coquille" refers, because all Mayotte specimens we examined have 6-fold dentition.It could even be the fifth tooth, i.e. the shallow columellar denticle, of the paralectotype of D. m. minuscula comb.nov., since Morelet (1881) is not explicit about the shell he is referring to.This raises another unfortunate possibility: that the paralectotype of D. m. minuscula comb.nov., apparently from Anjouan, was in fact a specimen without type status that was added later, and may even have come from Mayotte (or elsewhere), which would accord with Morelet's (1881) amendments to his description.However, we have no other reason to doubt the existing labels.
We here introduce the name D. m. mahorana subsp.nov.for the larger, coeloconoid specimens from Mayotte, the name fischeriana Morelet being unavailable (see above).They are indeed larger than the two specimens of D. m. minuscula comb.nov.(the size ranges do not overlap), are more elongate, have a more coeloconoid spire, finer and more numerous ribs, and 6-fold dentition including two shallow columellar denticles.These same features also distinguish them from D. radius comb.nov.s.l., which they overlap in size but only barely in the higher number of ribs per millimetre.Although as with D. radius comb.nov.s.l., it is difficult to distinguish intra-and interspecific variability, it is clear that the differences between the holotype of D. m. mahorana subsp.nov.and the lectotype of D. m. minuscula comb.nov., each collected on different islands, are substantial and sufficient for most modern authors to consider them distinct species.Alternatively, and given the residual uncertainty about the paralectotype of D. m. minuscula comb.nov., they may form part of a complex of subspecies.Again, further data is needed to address this.

Other material examined
None.

Description
Shell (Fig. 41).Large (4.10 mm high x 2.20 mm wide), of 6.25 whorls.Subconical (maximum width being in bottom third of the shell, at body whorl).Spire narrowly acuminate, almost cyrtoconoid (convex) rather than coeloconoid (spire angle 52°).Apex sharply pointed.Embryonic whorls punctate or malleate, rather than merely granulate.Later whorls with relatively fine ribs (about 14 per mm on penultimate whorl).Sutures of intermediate depth.Umbilicus narrowly open.Peristome incomplete parietally.Dentition weak, 3-fold (although could be interpreted as 2-fold), consisting of: one lamellalike parietal tooth, with a swelling above it that recalls the one in D. conoidea; one weak palatal tooth, not forming a parieto-palatal sinus; and one very weak, shallow columellar swelling.Further minute swellings just perceptible in the holotype (Fig. 41) were not noted by Verdcourt (1994) who interpreted the dentition as 2-fold.Shells and anatomy of juveniles unknown.

Range and habitat
Forest at the type locality, southeastern Tanzania.

Remarks
This species differs from D. conoidea comb.nov. in its weaker dentition, smaller size, and in having punctate apical whorls.(Verdcourt 1996).In the description of D. rondoensis comb.nov., Verdcourt (1994) discussed a resemblance only to Gulella galactochila (Crosse, 1885), a much larger and more broadly acuminate Tanzanian species that we consider to lack the characteristic features of Dadagulella gen.nov.Although G. galactochila has not been dissected, the anatomy of another species very similar to it (G.udzungwensis van Bruggen, 2003) lacks the anatomical features of Dadagulella gen.nov.(Rowson unpublished).In his discussion of D. conoidea comb.nov., Verdcourt (1996)

Other material examined
None.

Description
Shell (Fig. 42).Large (5.5 mm high x 2.80 mm wide), of 8.0 whorls.Subconical (maximum width being in bottom third of the shell, at body whorl).Spire narrowly acuminate, almost cyrtoconoid (convex) rather than coeloconoid (spire angle 48°).Apex sharply pointed.Embryonic whorls "probably smooth but worn" (Verdcourt 1996).Later whorls with relatively weak ribs (about 11 per mm on penultimate whorl).Sutures relatively shallow.Umbilicus narrowly open.Peristome incomplete parietally, or nearly so.Dentition 3-fold (although could be interpreted as 4-fold), consisting of: one lamella-like parietal tooth, with a swelling above it that recalls that in D. rondoensis comb.nov.; one strongly bifid palatal tooth (or pair of teeth), not forming a parieto-palatal sinus; and a shallow columellar tooth or denticle.Shells and anatomy of juveniles unknown.

Range and habitat
Altitude and habitat not stated but probably in lowland forest at approximately 200 m at the type locality, northeastern Tanzania.Another species (D. radius comb.nov.) also occurs at Kwamgumi.& Putzeys, 1923) superficially resembles some Dadagulella gen.nov. in size and in its broadly conical spire.However, we agree with Adam et al. (1995) and Schileyko (2000) that its other shell features, including the inrunning palatal fold, support its classification among the subgenera of Ptychotrema L. Pfeiffer, 1853.Other Ptychotrema can likewise be distinguished from Dadagulella gen.nov.by these folds.Finally, juvenile Dadagulella gen.nov.are distinct from the East African Juventigulella Tattersfield, 1998, with which they occur at several Tanzanian sites (Tattersfield 1998b) in lacking the downturned aperture of adult Juventigulella.

Salivary glands
The shape of Dadagulella's salivary glands differs from that of the type species of Gulella in which the united gland is not appreciably divided into two lobes (Rowson & Herbert, unpublished).

Radula
Dadagulella gen.nov. is highly unusual among Streptaxidae in having multicuspid radular teeth.Aiken (1981) believed the contrast between the radula of D. browni comb.nov.and of all other South African Gulella he studied was indicative of a difference in diet.The only prior reports of multicuspid streptaxid radulae appear to be Connolly (1930) and Verdcourt (1953) (see also Verdcourt 1990).Connolly (1930) Figs described the radula of the Ugandan Conogulella conospira subsp.polynematica (Pilsbry, 1919) as consisting of evenly bicuspid teeth (formula 47-1-47); this is also seen in other Conogulella species, the cusps being nearly equal in size (A.J. de Winter 2012, pers. comm.).Verdcourt (1953) described the radula of the Tanzanian Gulella usambarica (Craven, 1880) as consisting almost entirely of multicuspid teeth (formula 26-1-26); again, the cusps are nearly equal in size.Sequence data (Rowson et al. 2010a) show that Dadagulella gen.nov. is only distantly related to G. usambarica.Thus a relationship between Dadagulella gen.nov.and Conogulella based on the multicuspid radula cannot be ruled out, but remains unproven since multicuspid teeth occur in distantly related lineages.

Genitalia
Dadagulella gen.nov.differs from the type species of Gulella (Rowson & Herbert, unpublished) in having a swelling of or diverticulum on the vas deferens, a muscular apex, an apical penial "scoop" and one or more large apical penial hooks, and a smaller number of penial hooks in total.The genitalia differ or hybridizing species, while the more distinctive populations (several of them montane endemics) are fully isolated species that separated earlier.
Beyond East Africa, Dadagulella gen.nov. is represented by at least one species in Malawi and Zambia, two in eastern Mozambique, one in eastern South Africa and one on the Comoros archipelago.The genus does not appear to have been found on Madagascar, although the genus Gulella s.l. is richly represented there (e.g.Emberton 2001).There is some shell resemblance between Dadagulella gen.nov.and the following Madagascan species: G. ambatovakiae Emberton, 2001;G. benjamini Emberton & Pearce, 2000;G. hafa Emberton, 2001;G. hafahafa Emberton, 2001;G. mahafinaratra Emberton, 2001;G. manomboae Emberton, 2001;G. michellae Emberton, 2001;G. vakinifia Emberton, 2001 andG. vatosoa Emberton, 2001.This is a heterogenous group of species that does not key out together in the key of Emberton (2001).In each case the spire is acuminate, although slightly less so than in most Dadagulella gen.nov.. Juvenile teeth are not mentioned in the text of Emberton (2001) and a juvenile shell of one species (a paratype of G. hafahafa) is figured and appears to lack apertural teeth.
The genitalia of G. benjamini were figured by Emberton & Pearce (2000) and show an apical caecum and two longitudinal pilasters with a broad area between them.There is no apical scoop.The genitalia of G. reeae Emberton & Pearce, 2000 in the same paper have a vas deferens and pilasters more typical of Gulella (Rowson & Herbert unpublished).The anatomy of G. vatosoa is broadly identical to that of G. benjamini (unpubl.obs.).The anatomy of G. hafahafa, which is a Gulella based on sequence data (Rowson et al. 2010) is unlike that of G. benjamini or G. vatosoa in having few, larger hooks (unpubl.obs.) and unlike that of Dadagulella gen.nov.We conclude that Dadagulella gen.nov.as recognised here is not yet known from Madagascar.If Dadagulella gen.nov.and Gulella are indeed sister groups, these ibservations support an African, rather than Madagascan, divergence of the two.
. (Figs 73-83) (known from six species) Hermaphroditic duct diverticulum (talon) short, large, sausage-shaped, not convoluted.Bursa copulatrix attending albumen gland.Acini of prostate indistinct to distinct.Vagina attenuate.Oviduct often containing a single large egg.Vas deferens either thickened prior to insertion on penis, or appearing as such but actually with a diverticulum lying parallel to it.Vas deferens entering penis subapically.Penial retractor muscle branching off columellar muscle, attaching partly to vas deferens, thus sometimes bifid or nearly so.Penis elongate, tubular.Penial sheath absent, but lower part sometimes surrounded by a thin sheath-like layer contiguous with walls of lower penis.Interior of penis with weak radial pilasters and small rhombic pads, sometimes with a longitudinal pilaster or short rounded lobe.Apical part of penis with a spatulate or broad "scoop".One end with a microscopically serrated tip, the other end deeply embedded in muscular apex of penis.Scoop usually associated with one or two large, broad hooks, lying just behind or underneath it.Scoop and hook(s) could conceivably act together as a grip or pincer.Elsewhere in penis, a longitudinal row or group of few (<40) short, simple hooks mounted on rhombic pads."Spermatophore" (see Discussion) detected in two species: comma-shaped, lying with reservoir in vagina with longitudinally ribbed tail extending into mid .Aiken 1981)m three species) With a unicuspid central tooth and 9-15 laterals in each half-row, diminishing gradually in size laterally.Most or all laterals distinctively bicuspid or multicuspid, with outer cusps smaller or much smaller than inner cusps.Teeth are somewhat delicate (or flexible;Aiken 1981)and are short and flake-like at the ventral end of the radular ribbon.genitaliapenis.End of tail probably originally weakly attached to wall of penis [as in one specimen of D. radius radius(Preston, 1910) comb.nov.]butsubsequently detached.Partially digested tail fragments present in bursa of one specimen of D. pembensis sp.nov.
D. r. radius comb.nov.andD. b. browni comb.nov., and thus distinct from either, yet difficult to place.It is larger and not as squat as other D. browni comb.nov.s.l., and lacks the additional basal denticle and shallower columellar dentition.Conversely, it has a parietal denticle not seen in D. radius comb.nov.s.l, is smaller and squatter than most D. radius comb.nov.s.l., and has a longer and narrower parieto-palatal sinus than any D. radius comb.nov.s.l.Mafia Island, from which no other Dadagulella gen.nov.are yet known, lies at almost the same latitude (7.8°S) as the apparent northernmost limit of D. b. browni comb.nov. in mainland Tanzania.Given the morphology of this specimen, its latitude and its isolation as an island population, we treat it as a subspecies of D. browni comb.nov.
Bruggen & Van Goethem, 1999) and climatic regions.Although several snail species are known to range between South and East Africa, most are either species of the coastal strip, or are widely distributed throughout the entire area.Dadagulella gen.nov.hasnotbeenrecordedfrom much of the intervening area of East Africa and is represented in the Albertine Rift otherwise only by D. selene (vanBruggen & Van Goethem, 1999)comb.nov.It remains possible that the Semuliki population has descended from D. b. browni comb.nov., introduced by man from Tanzania or further to the south, and that the morphological differences are mainly ecophenotypic.However, in the light of these differences and the great geographic separation, we treat it as a subspecies of D. browni comb.nov.aswedo with D. b. mafiensis subsp.nov.Gulella delgadaMuratov, 2010: 274, 276-277, figs 37, 39-45.

Table 1 Etymology
Its shell features are consistent with inclusion in Dadagulella gen.nov.although the apex is more rounded than in other species.A slightly or strongly rounded apex occurs in D. selene comb.nov.andD. meredithae comb.nov.The parieto-palatal sinus, hidden basal denticle, and columellar dentition of D. nictitans comb.nov.allow it to be separated from other species.After Frontier Tanzania, the organisation which collected the specimens; given the ending '-arum' for a feminine noun in the genitive plural.
placed D. browni comb.nov.They noted that within this group D. selene comb.nov.was the most weakly sculptured and had distinctive dentition.These comments are still applicable among the larger number of species we attribute to Dadagulella gen.nov.However, like D. browni semulikiensis subsp.nov., D. selene comb.nov. is notable for occurring far to the northwest of other Dadagulella gen.nov species.It deserves further study from the perspective of Conogulella Pilsbry, 1919 (see Discussion).
Preston (1910)m.minuscula comb.nov.(underfischeriana) in the subgenus Ennea (Uniplicaria) L. Pfeiffer, 1856, it is very unlike Pupa cerea Dunker, 1848, the type species of Uniplicaria.Preston (1910)made a more relevant comparison in his description of Ennea radius, noting that his species had coarser ribs, a columellar denticle, and a bifid palatal tooth that were absent in D. m. minuscula comb.nov.Given these remarks and the fact that Preston cited only Anjouan as a locality for D. m. minuscula comb.nov., it thus appears he examined only the lectotype of the latter or material that was very like it.We agree that these features distinguish the lectotype of D. m. minuscula comb.nov.from that of D. r. radius comb.nov.However, the paralectotype (if it is such; see also below) of D. m. minuscula comb.nov., while having similarly fine ribs, has a stronger shallow columellar denticle that resembles that of D. r. radius comb.nov.Although we have seen no mainland specimen that exactly matches either of them, both specimens of D. m. minuscula comb.nov.fall within the range of variation seen in D. r. radius comb.nov. in other respects.It is therefore possible that the two taxa are synonymous, in which case Morelet's name would take priority over Preston's.It is even possible that D. minuscula comb.nov.s.l.consists of populations of D. radius comb.nov.s.l.derived from specimens introduced from the African mainland (the alternative, that D. radius comb.nov.s.l. was introduced into East Africa from the Comoros appears unlikely given the variation seen in East African populations and the many similar species there).That said, the isolated, volcanic Comoros archipelago comprises a region of endemism in itself and D. minuscula comb.nov.s.l.could easily be a Comoros endemic whose overlapping variation with D. radius comb.nov.s.l. is due to homoplasy.Resolving the relationships between these two taxa, and D. m. mahorana subsp.nov.below, is likely to require anatomical or molecular data.Until such information becomes available, and while we focus on other issues within Dadagulella gen.nov., we maintain the two species as separate.
Along with D. conoidea comb.nov.andD. delta sp.nov. it has weaker dentition than other Dadagulella gen.nov.However, both D. rondoensis comb.nov.and D. conoidea comb.nov.are distinctively more conical, i.e. less ovate than other Dadagulella gen.nov.These two are attributed to the genus somewhat speculatively, on the basis of their acuminate spire and pointed apex.These features mean they do not obviously fit into Gulella or any of its named subgenera, or indeed other plausible .nov., may not be significant in this respect (see Rowson 2007b for a discussion on the value of apical sculpture in distinguishing African streptaxid genera).The apex of D. conoidea comb.nov. is less obviously punctuate, although it may have been worn smooth (Verdcourt, 1994).No anatomical or juvenile shell data are available for either species, both being known from single specimens.The punctuate apex of D. rondoensis comb.nov., unique in Dadagulella Figs 41-42.Adult shells of Dadagulella gen.nov.species.41.D. rondoensis(Verdcourt, 1994)comb.nov., holotype, Rondo (photo by R. Janssen).42.D. conoidea comb.nov., holotype, Kwamgumi  (after Verdcourt 1996).gen made no reference to either D. rondoensis comb.nov.orG.galactochila,butonly to two species that we here treat in Dadagulella gen.nov.(D.r.radius comb.nov.andD.cuspidatacomb.nov.).We contend firstly that D. rondoensis comb.nov.andD.conoidea comb.nov.aremoresimilar to one another than either is to G. galactochila, and secondly that the resemblance between D. conoidea comb.nov., D. r. radius comb.nov.andD.cuspidata comb.nov.extends also to D. rondoensis comb.nov.. Our attribution of them to Dadagulella gen.nov.reflects this point of view.Gulella conoideaVerdcourt, 1996: 135-137, fig. 1.