Four new genera of the Ceratonotus group (Copepoda, Harpacticoida), including the description of two new species

. In the framework of an ongoing extensive phylogenetic evaluation of the Ceratonotus group (Copepoda, Harpacticoida, Cletodidae), Poropsyllus menzelae gen. et sp. nov. from the sublittoral of south-western Cyprus (eastern Mediterranean Sea) and Paratouphapleura aaroni gen. et sp. nov. from the western Weddell Sea (Antarctica) are described. Both new species fit the autapomorphies of the Ceratonotus group but cannot be assigned to any of the genera so far known. Instead, each new species presents a set of derived characters that justify their placement in new genera, Poropsyllus gen. nov. and Paratouphapleura gen. nov., respectively. Furthermore, a comparison of the species placed in Ceratonotus Sars revealed that because of exclusive morphological deviations, Ceratonotus concavus Conroy-Dal-ton, C. C. George, and C. vareschii George should be excluded from Ceratonotus and transferred to a new monophylum, Tauroceratus gen. nov. Likewise, Polyascophorus monoceratus George, Wandeness & Santos is characterized by several apomorphies that justify its transfer from Polyascophorus to a new taxon, Pseudopolyascophorus gen. nov. The Ceratonotus group is therefore increased to 31 species assigned to 13 genera. The systematic modifications conducted and resulting phylogenetic consequences are discussed in detail. group sensu Conroy-Dalton Body elongate, cylindrical, podoplean boundary between pro- and urosoma inconspicuous. Sexual dimorphism in A1, P3, P5, and P6; female with GDS due to fusion of last (P6-bearing) thoracic and first abdominal (genital) somites. Cphth about ¼ of total body length, with some sensilla and long tube pores laterally and dorsally; moreover, with small, sensilla-bearing frontolateral horns (FLH), ventrally directed cephalothoracic anterior lateroventral processes (CLVPa), and bifurcate cephalothoracic posterior lateroventral processes (CLVPp). Cephalic front produced into a massive diverging peak. P2–P4-bearing pedigerous somites with dorsal cuticular processes. Rostrum absent, original central position indicated by small paired membranous projections accompanied by a pair of sensilla and 1 tube pore. Body somites except last thoracic somite (= anterior half of female GDS) and telson laterally with 1 long tube pore. Thoracic body somites dorsally also with 1 long tube pore. Telson broader than long, trapezoid in dorsal view, anal operculum flanked by 2 sensilla, posterior margin with row of fine spinules. FR long and slender, diverging, with 7 setae. Female A1 slender, 4-segmented, male sexually dimorphic, number of segments unknown. A2 without exopod, allobasis with 2 abexopodal setae; endopod with 2 spines and 1 slender additional seta; apically with 5 setae, 3 of which geniculate. Intercoxal sclerites of P1–P4 slender, bow-like; P1 with transversely elongated basis 2-segmented exopod, endopod by 1 long bare seta; bases of P2–P4 showing extreme transverse elongation, endopods, P3,


Introduction
Currently the Ceratonotus group sensu Conroy-Dalton (2001) comprises nine genera: Arthuricornua Conroy- Dalton, 2001, Ceratonotus Sars, 1909, Dendropsyllus Conroy-Dalton, 2003, Dimorphipodia Lee & Huys, 2019, Dorsiceratus Drzycimski, 1967, Echinopsyllus Sars, 1909, Polyascophorus George, 1998, Pseudechinopsyllus George, 2006, and Touphapleura Conroy-Dalton, 2001Drzycimski 1967;George 1998George , 2006aConroy-Dalton 2001;Conroy-Dalton 2003a;Lee & Huys 2019). A first detailed systematic evaluation of the Ceratonotus group was made by Conroy-Dalton (2001), who in that context established the name, recognizing Touphapleura as the most ancestral representative. Subsequent studies focused rather on the description of new species, often resulting in the establishment of new genera (Conroy-Dalton 2001, 2003aGeorge 2006aGeorge , 2006bGeorge & Plum 2009;Wandeness et al. 2009;Lee & Huys 2019), but only Lee & Huys (2019) and George (2020) provided -about two decades after Conroy- Dalton's (2001) first attempt -new insights into the systematic relationships within the Ceratonotus group itself. While Lee & Huys (2019) focused in particular on the homologisation of the cuticular body processes, setular/spinulose tufts, and tubercles that are characteristic of the Ceratonotus group, George's (2020) phylogenetic evaluation resulted in the transfer of the taxon from the Ancorabolidae Sars, 1909, to the Cletodidae T. Scott, 1904, sensu Por (1986. In the framework of an ongoing phylogenetic evaluation of the Ceratonotus group, a new genus, Poropsyllus gen. nov., is established to accommodate a new species from the eastern Mediterranean Sea. A second new species resembling Touphapleura in several (plesiomorphic) character states but at the same time presenting derived features is described from the high Antarctic and placed in a new taxon, Paratouphapleura gen. nov. Furthermore, four species, so far assigned to the taxon Ceratonotus, are transferred into a new genus Tauroceratus gen. nov. Finally, Polyascophorus monoceratus  is excluded from that genus and placed in Pseudopolyascophorus gen. nov. The respective systematic modifications, based on 27 morphological characters and justifying the establishment of the above-named new taxa, are discussed in detail.

Material and methods
The two specimens of Poropsyllus menzelae gen. et sp. nov. described here were collected by Prof. F.D. Por in October 1968 southwest of Cyprus (eastern Mediterranean Sea, Fig. 1) (Por et al. 1972) using an Ockelmann detritus sledge (Ockelmann 1964). For the identification and description, the partly damaged individuals were embedded in glycerol, and each was placed on one slide. Because dissection would have caused further destruction of the individuals, species identification and drawings were made without dissection with a camera lucida on a Leica DMR compound microscope equipped with differential interference contrast. The material is deposited at the National Natural History Collections of the Hebrew University of Jerusalem, Israel (HUJ). The material of Paratouphapleura aaroni gen. et sp. nov. was collected during the ANDEEP II expedition ANT XIX/4 of RV Polarstern in 2002 (Fütterer et al. 2003). Sampling was done at station #133 on the eastern continental slope off the Antarctic Peninsula (Fig. 2) with a multiple corer (MUC) (Gooday et al. 2004). It comprises three females and three males here designated as type material. The specimens showed a remarkable coverage with compact detritus and were partly damaged (antennulae broken, cephalothorax partly crushed, furcal setae missing), but a detailed species description was possible. The type material is deposited in the collection of the Senckenberg Forschungsinstitut und Naturmuseum Frankfurt/Main, Germany (SMF).
For the phylogenetic evaluation, morphological comparison was based on original species (re-) descriptions and, so far as possible, on available (type) material.
General scientific terminology follows a literal translation of Lang (1948) with additional terms from Huys & Boxshall (1991). Phylogenetic terminology is translated from Ax (1984). The terms 'telson' and 'furca' are adopted from Schminke (1976). The terminology regarding cuticular outgrowths and ornamentation of the cephalothorax and body somites follows Lee & Huys (2019).

Etymology
The generic name is given in respectful remembrance of the collector of the species, Prof. Dr Francis Dov Por (Israel) and is a compound of the collector's name and the Greek ψύλλος [psillos] ('flea'), a term often used in the naming of taxa of the Ceratonotus group (e.g., Dendropsyllus, Echinopsyllus, Pseudechinopsyllus). Gender: masculine.

Type and only species
Poropsyllus menzelae gen. et sp. nov.
Both specimens show several instances of damage, mainly loss of setae, segments of appendages, and both antennular segments and cuticular processes (male allotype). Dissection, which would have caused further destruction of the individuals, was not conducted, but all parts except the maxillula were drawn and described.

Description
Female Habitus (Fig. 3A). Elongate, cylindrical (body length including FR 550 µm), podoplean boundary between pro-and urosoma inconspicuous. Cphth about ¼ of total body length, with some sensilla and long tube pores laterally and dorsally; moreover, with small frontolateral horns (FLH), ventrally directed cephalothoracic anterior lateroventral processes (CLVPa) (arrowheads in Fig. 3A), and bifurcate cephalothoracic posterior lateroventral processes (CLVPp). Cephalic front produced into a massive diverging peak, from which the A1 arises. Rostrum (Figs 3A, 4A) absent, original central position indicated by small paired membranous projections accompanied by a pair of sensilla and 1 tube pore. P2-P4-bearing pedigerous somites with small dorsal cuticular processes (DP1-DP3); each process carrying a sensillum at its tip (most of them broken in Fig. 3A). Body somites except last thoracic somite (= anterior half of female GDS) and telson laterally with 1 long tube pore. Thoracic body somites with additional dorsal long tube pore. First abdominal somite fused with last thoracic body somite to form a GDS. Thoracic part of GDS dorsally with pair of diagonal cuticular ridges; abdominal part of GDS and abdominal somites except telson with abdominal lateral setulose tufts (AST1-AST3). Telson broader than long, trapezoidal in dorsal view, anal operculum flanked by 2 sensilla, posterior margin with row of fine spinules. FR ( Fig. 3A-B). Diverging, rami slender, about 11 times as long as broad and longer than abdomen and GDS together, bearing 7 bare setae (Fig. 3B). Setae I and II inserting laterally, standing close together, I minute, II twice as long as I; III inserting subapically on outer margin; setae IV and V located apically, IV slightly smaller than III, and V as long as fifth pedigerous somite, abdomen, and FR combined (Fig. 3A); VI as long as IV, inserting apically on inner margin; VII tri-articulate, arising dorsally from small knob. a1 (Fig. 4B). 4-segmented, long and slender. First segment longest, second to fourth segments of almost the same size. First 3 segments with long spinules (several spinules broken in Fig. 4B). Several setae broken in Fig. 4B; first segment distally with 1 seta (broken); second segment with 7 setae (6 broken, 1 biplumose); third segment with at least 6 setae (all but 1 bare seta broken); pedestal for acrothek discernible close to apical margin (elements broken); fourth segment with 11 bare setae (1 apical seta broken), two of which fused with 1 small aes.
Mxl. Because dissection, which would have caused destruction of the individuals, was not conducted, no in situ description could be made, and the mxl was not drawn.
p5 (Fig. 5C). Baseoendopod and exopod fused. Baseoendopod with outer bipinnate seta arising from minute setophore and accompanied by 1 long tube pore. Endopodal lobe completely reduced, represented  by 1 long and 1 small bare seta. Exopodal lobe with 1 bipinnate outer seta and 3 apical setae, two of which bipinnate, the remaining one bare; subapically with long tube pore.
GF (Fig. 7A). With fused gonopores covered by slender genital operculum derived from the medially fused P6, whose minute lobes each end in a bare seta.

Male
The male resembles the female in most characters. Sexual dimorphism is expressed in a slightly smaller body size (480 µm incl. FR), in the A1, the P3 endopod, the P5, and the absence of a P6. a1 (Fig. 7B). Damaged, but sexual dimorphism still discernible. First segment as in female; second segment half as long as first, with 7 setae and long spinules on anterior margin; third segment about ⅓ the length of previous segment, with 1 bare seta. Following segments broken, not illustrated. a2 (Fig. 5A). Without exp. Allobasis with 2 abexopodal bare setae. Endopod laterally on distal half with 2 well-developed setae, one of which bipinnate, and with 1 small bare seta; additionally, with frill-like row of long fine spinules. Apically with 3 long geniculate setae (one broken); moreover with 1 bipinnate and 1 bare slender seta. Subapically with spinulose frill.

Type and only species
Pa. aaroni sp. nov.

Etymology
The generic name 'Paratouphapleura' is a combination of the Greek παρά [pará], meaning 'besides', 'beyond', and the genus name Touphapleura, pointing to the general morphological resemblance of Touphapleura and Paratouphapleura gen. nov. Gender: feminine.
FR (Figs 8A, 9C). Diverging, rami slender, about 3.5 times as long as broad and as long as telson and preceding somite together, with 1 small tube pore proximally on outer margin and bearing 7 bare setae ( Fig. 9C): setae I and II of almost the same length, inserting halfway on outer margin and set close together, I bipinnate, II bare; III bipinnate, inserting subapically on outer margin; setae IV and V located apically, IV bare, visibly smaller than III, V longest element, bipinnate; VI bare, even smaller than IV, inserting apically on inner margin; VII bare, tri-articulate, arising dorsally from small knob. a1 (Fig. 10A). Partly or completely broken in all three females. Most complete condition present in holotype: slender, 4-segmented, first and third segments of almost the same size, about twice as long as second and fourth segment. First and second segments with several long spinules, following segments without spinulose ornamentation. First segment with biplumose seta subapically; second segment with 8 setae (5 broken); third segment with 8 setae (2 broken), 2 of which forming acrothek together with aes; fourth segment with 3 lateral setae; apically with at least 5 setae; acrothek that might consist of 2 additional setae and aes broken, not discernible.
Mxp (Fig. 11E). Prehensile, syncoxa without spinules but with 1 biplumose seta on apical edge; basis with 2 rows of long spinules; endopod produced into long bare claw, basally accompanied by 1 tiny seta. p1 (Fig. 10B). With transversely elongated basis and 2-segmented exo-and endopod. Praecoxa small, triangular; coxa small, more or less rectangular. Basis with several long spinules on anterior margin, and with 1 inner and 1 outer element (broken in Fig. 10B). Exopodal segments of nearly the same size, exp-1 with row of spinules on outer distal margin, and with 1 outer bipinnate seta; exp-2 without spinules, with 1 bipinnate outer seta, and (sub)apically with 4 geniculate elements, all with row of pinnules previous to geniculation.

Male
The male (Fig. 8B) resembles the female in most characters. Sexual dimorphism consists of a slightly smaller body size (allotype: 410 µm, paratype 4: 417 µm, paratype 5: 459 µm), smaller dorsal cuticular processes DP1-DP3, the A1, the P3 endopod, the P5, and the absence of a P6. a1 (Fig. 14A). 7-segmented, subchirocer. First segment with long spinules on surface and anterior margin, and with 1 seta apically (broken in Fig. 14A); second segment as long as first, with 8 bare setae (two of which broken in Fig. 14A); third segment small, almost triangular, with 4 bare setae; fifth segment minute, with 2 small bare setae; sixth segment swollen, setation not discernible because of   position on the slide and the risk of breaking the A1 if it is turned (its description is therefore postponed until additional material is found) sixth segment small and squarish, without ornamentation; seventh segment twice as long as sixth, tapering posteriorly, with 9 bare setae, 2 of which form an apical acrothek together with 1 aes.
p3 endopod (Fig. 14B). 3-segmented, first segment small and unarmed, second segment about three times as long as first, ending in acute apophysis; third segment slightly shorter and narrower than first, not reaching end of apophysis, with 2 long biplumose setae apically.
p5 (Fig. 13B). Exopod separated from baseoendopod, with several long spinules and 2 outer and 2 apical bipinnate setae; additionally, with 1 subapical bare seta but without tube pore; baseoendopod as in female but endopodal lobe smaller, likewise the single endopodal seta, which is small and bare.

Type and only species
Pseudopolyascophorus monoceratus  gen. et comb. nov.

Etymology
The genus name is compound by the Greek ψευδής [pseudes] ('misleading', 'deceiving') and the genus name Polyascophorus, indicating an ostensible morphological similarity of Polyascophorus and Pseudopolyascophorus gen. nov. Gender: masculine.

Discussion
Character 3, rostrum lost: George (2020) hypothesized the rostral diminution as autapomorphic for the Ceratonotus group. Within that taxon, a further rostral development took place, resulting in its complete absorption into the cphth. Such complete reduction is observable in Poropsyllus menzelae gen. et sp. nov. (Figs 3A, 4A) and thus considered an autapomorphy of that genus. Nonetheless, the same is present in the genera Ceratonotus, Dendropsyllus, and Tauroceratus gen. nov. (= CeDeTa). But as these taxa do not share any other apomorphy assigned to Poropsyllus gen. nov., which for its part lacks the synapomorphies uniting CeDeTa -for example, the development of dendroid body processes, a 3-segmented female A1, and the loss of the proximal abexopodal seta on the A2 allobasis -the complete loss of the rostrum is regarded here as convergence between Poropsyllus gen. nov. and CeDeTa. That assumption is substantiated by the circumstance that the CeDeTa group shares a set of derived characters with several other genera of the Ceratonotus group, which are, however, absent in Poropsyllus gen. nov. These are (among others) (i) strongly elongated frontolateral horns (FLH), (ii) the development of cephalothoracic laterodorsal processes (CLDPp), (iii) the remarkable elongation of dorsal processes DP1-DP3, and (iv) the lateral bend of the cephalothoracic posterior lateroventral processes (CLVPa). It is therefore concluded that CeDeTa and Poropsyllus gen. nov. belong to different lineages within the Ceratonotus group.
Character 4, furcal seta II bare: most genera of the Ceratonotus group present a uni-or bipinnate seta II on the furcal rami ( Fig. 17A-E). Only two taxa are characterized by a bare seta II, namely Pseudechinopsyllus (Fig. 17F) and Poropsyllus gen. nov. (Fig. 17G). As the supposed most primitive representative -Touphapleura (cf. Conroy-Dalton 2001) -bears a bipinnate seta II, which is retained in all except the above-mentioned two genera, the transformation into a bare element is considered here to be the derived state. Because Pseudechinopsyllus and Poropsyllus gen. nov. can each be characterized by clear autapomorphies (cf. George 2006), and as Pseudechinopsyllus shares several deviations with other representatives of the Ceratonotus group that are absent in Poropsyllus gen. nov. -pointing towards a comparatively basal branch-off of the latter within the Ceratonotus group -character 4 is seen here as a convergent autapomorphy for both genera.
Character 5, P1 endopod represented by 1 seta: as substantiated by George (2020), the Cletodidae are characterized by a derived non-prehensile P1, whose endopod is reduced in size, with enp-1 and enp-2 showing almost the same size. The Ceratonotus group can be characterized by more deviations, namely (i) the transverse elongation of the P1 basis, (ii) the loss of the endopodal element 3, and (iii) the transformation of the exopodal element V into a geniculated seta (cf. George 2020). Within that taxon  Sars, 1909, Dendropsyllus Conroy-Dalton, 2003, Tauroceratus gen. nov. Roman numerals indicate outer, Arabic numerals inner elements. Asterisks * indicate derivations referred to in the text. the P1 endopod underwent even further deviation. In Poropsyllus gen. nov. it is completely reduced and represented only by 1 seta. This condition is regarded as autapomorphic for that genus.
Characters 9 and 10, female P3 endopod, and P4 endopod absent: although the loss of the P2 endopod is not uncommon within the Ceratonotus group (cf. Lee & Huys 2019: 349, tab. 2 for review), the species described here is the only one that has also lost the endopods of the P4 and the female P3. These derived characters are considered here to be autapomorphic for Poropsyllus gen. nov.
Character 11, P5 extremely elongated, reaching anterior margin of telson: the P5 of Po. menzelae gen. et sp. nov. like P2-P4 shows a remarkable elongation (Fig. 3A), reaching the length of the entire urosoma excluding the telson. Such an elongated P5 is unique within the Ceratonotus group and constitutes a clear autapomorphy of the new genus.
Characters 12 and 13, P5 seta II lost, seta 4 bare: within the Ceratonotus group, the exopod(al lobe) of the P5 presents a series of deviations, as depicted in the scheme of Fig. 18. As a homologation of the exopodal elements seems possible, and given that Touphapleura (Fig. 18A) retains the ancestral condition with 2 outer (I, II), 2 apical (3, 4), and 1 subapical (5) inner bipinnate elements, their modification or loss can be recognized in the other species. As shown in Fig. 18, a certain gradual development of the P5 exopod might be evident, at least in some species. For example, seta 5, which retains its original bipinnate shape in Touphapleura (Fig. 18A) and most remaining taxa (Fig. 18E-H), shows an agglomeration of finer pinnae on its distal half in Polyascophorus and Pseudopolyascophorus gen. nov. (Fig. 18B), Arthuricornua (Fig. 18C), and Dimorphipodia (Fig. 18D). Other kinds of modifications are seen in Dorsiceratus (Fig. 18E) and Echinopsyllus (Fig. 18F). Especially in the context discussed here, two deviations are of particular interest: only Poropsyllus gen. nov. (Fig. 18G) and CeDeTa (Fig. 18H) have lost the outer seta II (character 12), which is retained in all remaining taxa. As with character 3 (loss of the rostrum), the complete reduction of seta II is seen as a convergent autapomorphy for both CeDeTa and Poropsyllus gen. nov. An exclusive deviation, hypothesized here as autapomorphic, is present in the shape of seta 4 of Poropsyllus gen. nov. (character 13), which is bare (Fig. 18G), whereas all remaining members of the Ceratonotus group retain the ancestral shape of a bipinnate seta.
Establishment of Paratouphapleura gen. nov. and assignment of Pa. aaroni gen. et sp. nov. A very first examination of specimens of Pa. aaroni gen. et sp. nov. may suggest a distinctive affinity to Touphapleura, due to its quite similar shape of, e.g., the habitus; the slight dorsoventral depression of the body; the shape, size, and ornamentation with a setular tuft of the rostrum (RST); the comparatively small size of the dorsal cuticular processes DP1-DP3; the lack of cuticular processes on the urosoma; shape and size of telson and FR; and the general shape of the swimming legs. These similarities point to a potential close relationship of Touphapleura and Paratouphapleura gen. nov., which is the object of an ongoing phylogenetic study. Character 14, cephalothoracic posterior lateroventral extensions (CLVEp) extended into jet-winglike cephalothoracic posterior lateroventral processes (CLVPp): Touphapleura presents the posterior margin of the cphth produced into cephalothoracic posterior lateroventral extensions (CLVEp) that carry posterior cephalothoracic setulose tufts (PCST, see below, character 16) (Fig. 15). Such CLVEp are missing in several other genera, i.e., Arthuricornua, Dimorphipodia, and Dorsiceratus, but apparently underwent further deviation in the remaining taxa, extending into quite variable cephalothoracic posterior lateroventral processes (CLVPp) (Fig. 15). Also, Paratouphapleura aaroni gen. et sp. nov. shows strongly developed CLVPp (Figs 8A,B,9B,15), which are triangular and directed slightly backward, reminiscent of the wings of a jet plane. This condition is not found in any other member of the Ceratonotus group and is thus considered here to be autapomorphic for Paratouphapleura aaroni gen. et sp. nov.
Character 15, posterior cephalothoracic setulose tufts (PCST) reduced: the CLVEp in Touphapleura are armoured with apical setulose tufts (PCST). These are lost in Paratouphapleura aaroni gen. et sp. nov., which instead carries a sensillum at the tip of each CLVPp (Figs 8A, B, 9B). Apart from the PCST, Touphapleura presents setulose or spinulose tufts at the lateral margins also of the body somites (TST1-TST3, GST, AST1-AST4, cf. Fig. 15). These are also observable in Paratouphapleura aaroni gen. et sp. nov. (and in varying composition in several other genera). As such tufts are not developed in the supposed sister-group Cletodes, their development is assumed here to have taken place in the common ancestor of the Ceratonotus group, therefore forming (a derived) part of the ancestral groundpattern. Subsequently, particular tufts were reduced secondarily and independently in several species. Consequently, the loss of the PCST in Paratouphapleura aaroni gen. et sp. nov. is hypothesized here to be autapomorphic for that species and therefore for the genus Paratouphapleura gen. nov.
Character 16, P3 exp-3 without tube pore: all genera of the Ceratonotus group (including the most primitive, Touphapleura) are characterized by a tube pore borne on the subapical margin of the P3 exp-3. At a generic level, only two exceptions occur: Poropsyllus gen. nov. and Paratouphapleura gen. nov. The presence of this tube pore is therefore interpreted here as the ancestral condition, which could be confirmed also for Cletodes meyerorum . Therefore, its reduction in Poropsyllus gen. nov. and Paratouphapleura gen. nov. is seen here as the derived state. As Paratouphapleura gen. nov. seems, however, to be closely related rather to Touphapleura than to Poropsyllus gen. nov., which on its side can be characterized by a set of 13 autapomorphies (see above) missing in Paratouphapleura gen. nov., convergent reduction is assumed in both taxa.
Compared with Paratouphapleura gen. nov. (and all remaining taxa of the Ceratonotus group), Touphapleura can also be characterized by one deviation that is regarded here to be autapomorphic for that genus: 17. Mandible palp lost seta 3 [seta 3 still present]; As members of the Cletodoidea, all members of the Ceratonotus group bear a unilobate mandibular palpus that carries at most 6 setae (cf. George 2020: 459, tab. 1, characters 28, 29). The homologisation of the setae is possible, as their location on the palpus is quite conservative in the different species. As shown in Fig. 19A, two setae located in the direction of the gnathobase correspond to the former basis; one seta situated on the opposite side represents the exo-, and three apical setae the endopod. In the Ceratonotus group, several modifications can be observed. For instance, Paratouphapleura gen. nov. still retains the original cletodoid setation of all six setae (Fig. 19A). That condition disqualifies George's (2020) assumed apomorphic state for the Ceratonotus group -that, on the basis of the data available at that time, all members of the Ceratonotus group were characterized by a mandibular palp carrying a maximum of 5 setae only (George 2020: 460, character 76). Homologisation of these elements reveals that apart from Paratouphapleura gen. nov. all remaining species show the reduction of one or two setae (Fig. 19B, C, E); Touphapleura therefore lost the seta 3 (Fig. 19D), which is regarded as autapomorphic for that genus.  (George, 1998 (George & Schminke, 1998). I. Tauroceratus vareschii (George, 2006) George, 1998 (type species), Po. gorbunovi (Smirnov, 1946), and Po. monoceratus . When establishing the genus, George (1998) also included Polyascophorus schminkei George, 1998, which was subsequently transferred into Touphapleura by Conroy-Dalton (2001).  added Po. monoceratus, justifying it by four apomorphies shared by all three species: (1) the bifurcated lateroventral posterior processes (here homologised with cephalothoracic posterior lateroventral processes (CLVPp); cf. Fig. 15) of the cphth; (2) the shorter P1 endopod, reaching at most ⅓ of the length of the exopod; (3) the FR are rounded on their outer apical margin; (4) the furcal setae IV, V, and VI displaced to the inner apical edge of the FR. The further establishment of Po. monoceratus as a distinct species was supported by five exclusive deviations: (5) the development of a single cuticular process (here homologised with DP5; cf. Fig. 15) dorsally on the first abdominal somite (= anterior half of female GDS); (6) the bifurcated cephalothoracic posterior lateroventral processes (CLVPp) with the anterior branch elongated, reaching almost the length of the posterior branch; (7) the furcal seta VII biplumose in its distal half; (8) the male P1 without endopod; (9) the apical setae on the P2 exp-3 bare and geniculated.  listed further deviations (the absence of cephalothoracic laterodorsal processes (CLDPp) in Po. martinezi and Po. gorbunovi, the elongated and bifurcated rostrum in Po. monoceratus, and the presence of a spinulose row dorsally on the second abdominal somite in the female of Po. monoceratus), but the authors felt unable to weight these features as plesio-or apomorphic and therefore refrained from their phylogenetic evaluation. Although neither Lee & Huys (2019) nor George (2020) questioned the systematics within Polyascophorus, a detailed comparative re-examination of the species based on the original descriptions (Smirnov 1946;George 1998;) as well as on the type material of Polyascophorus martinezi and Touphapleura schminkei revealed that the morphological differences between Po. monoceratus and the remaining two species are so grave that the retention of the former in Polyascophorus cannot be justified. Consequently, Po. monoceratus is excluded from Polyascophorus and placed in a new genus, Pseudopolyascophorus gen. nov., as Ps. monoceratus  comb. nov.
Compared with Polyascophorus, the new genus can be characterized by several autapomorphies, some of which correspond to those listed by  modification. Its presumably most ancestral representative -Touphapleura -presents a narrow and small rostrum that is equipped with a pair of sensilla, a medial tube pore, and a rostral setulose tuft (RST) on its apical margin (Fig. 20A, cf. George 1998). This rostral shape is hypothesized here to have evolved in the last common ancestor of the species assigned to the Ceratonotus group, thus constituting an autapomorphy for it. Besides Touphapleura, that rostral shape is -turning into a plesiomorphic state within the Ceratonotus group -retained in Arthuricornua (cf. Conroy-Dalton, 2001), Dimorphipodia (cf. Lee & Huys 2019), and Polyascophorus (Fig. 20B) (cf. Smirnov 1946;George 1998), which furthermore show a slight protrusion of the lateral edges of the cephalothoracic frontal peak.
The phylogenetic evaluation of the rostral development within the Ceratonotus group is the object of ongoing studies. Noteworthy on the topic discussed here, however, is that two evolutionary directions had apparently been pursued: (i) a rostral elongation (Dorsiceratus (Fig. 20C), Echinopsyllus (Fig. 20D)  Character 19, anterior branch of cephalothoracic posterior lateroventral processes (CLVPp) elongated, almost as long as posterior branch: the development of bifurcated CLVPp was assumed to support the close relation between Polyascophorus gorbunovi (Smirnov 1946), Po. martinezi, and Po. monoceratus. Indeed, the general shapes of these processes are very similar. The main difference, already noted by , is the length of the anterior branch of the processes. It is much shorter than the posterior branch in both Po. gorbunovi and Po. martinezi but reaches almost the same length as the latter in Po. monoceratus. , however, regarded that difference as specific. Instead, in the evaluation presented here, that deviation is considered a generic autapomorphy, because together with the remaining six derived features it underlines the outstanding phylogenetic position of Po. monoceratus, which allows its displacement into a new genus, Pseudopolyascophorus gen. nov., as Ps. monoceratus comb. nov.
Character 20, cephalothoracic laterodorsal processes (CLDPp) developed:  rejected the assumption of Conroy-Dalton (2001), that the bifurcated cephalothoracic posterior lateroventral processes (CLVPp) of Polyascophorus gorbunovi and Po. martinezi, which both lack CLDPp, had migrated from an original laterodorsal to their lateroventral position. That rejection was substantiated by the presence of both CLVPp and CLDPp in Pseudopolyascophorus monoceratus comb. nov. The development of the latter is hypothesized here as autapomorphic for Ps. monoceratus comb. nov. in comparison with Polyascophorus.
Character 21, DP5 developed: the development of a single dorsal process on the first abdominal somite (= posterior half of the female GDS) in Ps. monoceratus comb. nov. is unique within the Ceratonotus group. It has, however, been regarded as a specific apomorphy by  and was ignored in the discussion of body processes by Lee & Huys (2019). Nevertheless, that deviation is in fact a peculiar character of Ps. monoceratus comb. nov. and is thus seen here as a clear autapomorphy of Pseudopolyascophorus gen. nov. Character 22, furcal seta VII biplumose at distal half: as for character 21, the development of a biplumose furcal seta VII in Ps. monoceratus comb. nov. (George et al. 2013: 23, fig. 2a, c) is unique within the whole Ceratonotus group, whose remaining members present a bare seta VII. The derived biplumose seta is therefore considered here as autapomorphic for the new genus.
Character 23, maxillar endopod represented by 2 setae: in the Cletodoidea, the maxilla is characterized by a 1-segmented endopod that bears 2 setae (George 2020: 459: character 31). That condition is still retained in most species of the Ceratonotus group; at the genus level, only Touphapleura and Pseudopolyascophorus gen. nov. show a further deviation, namely the complete loss of the maxillar endopod and its representation by 2 setae only. Whether that deviation constitutes a synapomorphy of Touphapleura and Pseudopolyascophorus gen. nov., indicating their closer phylogenetic relationship inside the Ceratonotus group, is the object of ongoing investigation.
Character 24, P1 of male without endopod: within the Ceratonotus group, the loss of the P1 endopod, which is no longer represented by even 1 seta, is reported from several taxa (Arthuricornua, Dimorphipodia, Echinopsyllus, Pseudechinopsyllus) (Conroy-Dalton 2001; Conroy-Dalton 2003b; George 2006a; Lee & Huys 2019). In Ps. monoceratus gen. et comb. nov. this complete reduction took place in the male only, whereas in Poropsyllus gen. nov. the P1 endopod is represented by 1 seta (Fig. 5B); the remaining species (including Polyascophorus) still retain an at least a 1-segmented endopod. Thus, the loss of the P1 endopod exclusively in the male, which points towards a sexual dimorphism in Ps. monoceratus gen. et comb. nov., is seen as autapomorphic for that taxon. Whether the simultaneous loss of the P1 endopod may constitute a synapomorphy of the above-named taxa is object of an ongoing phylogenetic study.
Character 25, P2 exp-3 apical setae bare, geniculated: as for characters 21 and 22, the transformation of the apical setae in the P2 exp-3 from bipinnate/biplumose to bare but geniculated elements is a deviation that is exclusively present in Ps. monoceratus gen. et comb. nov. It is hypothesized here to be autapomorphic for Pseudopolyascophorus gen. nov.
The quality and exclusive combination of characters 18-25 justify the translocation of Polyascophorus monoceratus into a new genus.
The most peculiar characteristics of Ceratonotus pectinatus Sars, 1909, the first species that was described for that genus (Sars 1909), are the complete lack of a rostrum on the frontal margin and the presence of cuticular processes on cphth and body somites, described as 'comb-like' by Sars (1909) but later named 'dendroid processes' by Conroy-Dalton (2001, 2003a and following authors. Currently, the genus Ceratonotus Sars, 1909 encompasses 8 species (cf. George 2020); its closest relative is presumably Dendropsyllus Conroy-Dalton, 2003, which was established by Conroy-Dalton (2003a) to accommodate 2 species described by George & Schminke (1998) from the southern hemisphere. By now, Dendropsyllus encompasses 5 species (George 2020).
The main difference between these two genera is the presence of dendroid processes also on the first abdominal somite (= posterior half on the female GDS) in Ceratonotus (= DP5), whereas in Dendropsyllus these processes are developed as conical tubercles (= DT2) only (Conroy-Dalton 2003a; George 2006b). Moreover, Dendropsyllus is characterized by the loss of the P2 endopod, which is still present in most Ceratonotus species, with the exception of C. steiningeri George, 2006, which just like the Dendropsyllus species lost the P2 endopod (cf. Conroy-Dalton 2003a; George 2006b).