Three new species of the genus Rhyzobius Stephens, 1829 from New Guinea (Coleoptera: Coccinellidae: Coccidulini)

Three new Papuan species of the ladybird genus Rhyzobius Stephens, Rhyzobius albinos sp. nov., R. atramentarius sp. nov. and R. serratus sp. nov., are described, diagnosed and illustrated. An updated key to species of Rhyzobius from new Guinea is provided.


Introduction
The family Coccinellidae Latreille, 1807, with bright colouration in most of the species, is one of the best recognized groups of beetles. with over 6000 species, it is the largest beetle family within the superfamily Coccinelloidea Latreille, 1807Latreille, (robertson et al. 2015.
The position of the genus Rhyzobius stephens, 1829 within the family Coccinellidae has changed over the decades. stephens (1829), while establishing the genus, placed it close to Scymnus kugelann, 1794 in an informal group called "Pubescentes". mulsant (1850) in his monograph of Coccinellidae, transferred this genus to the subfamily scymninae mulsant, 1846 (scymniens), containing mostly hairy species. subsequently, it was classified within the subfamily rhizobiinae Crotch, 1874 (rhizobiides) (Crotch

Material and methods
The specimens examined were collected during the project "our Planet reviewed iBisCA niugini 2012-2013" (Leponce et al. 2016 in wanang station and along a west-East transect on the slopes of mount wilhelm in Papua new Guinea. They are kept in the muséum national d'histoire naturelle in Paris (mnHn) and the museum and institute of zoology, Polish Academy of sciences (miz).
Genitalia were dissected, cleared in a 10% koH solution, and placed in glycerol on slides for further study. measurements were recorded as follows: total body length (TL), from apical margin of clypeus to apex of elytra; width (Ew), across both elytra in the widest part; pronotal length (PL), from the middle of anterior margin to margin of basal foramen; pronotal width (Pw), across widest part; elytral length (EL), along suture including scutellum. All colour images were taken using a stereo microscope Leica mz 16 with a digital camera iC 3D; final images were produced using Helicon Focus 5.0X64 and Adobe ® Photoshop Cs6 software. The sEm photographs were taken in the Laboratory of scanning microscopy, miz (warsaw), using a scanning electron microscope HiTACHi s-3400n under low vacuum conditions. Terminology used for morphology follows Ślipiński (2007) and Ślipiński & Tomaszewska (2010).

Etymology
The specific epithet is a noun in apposition, it means 'albino' in Polish and refers to the bright colouration of most of the ventral surfaces, not observed in other species of Rhyzobius.
Head (Fig. 1D). Dorsally exposed with eyes almost entirely visible; ventral antennal grooves distinctly circularly bent towards outer margin of eye; corpotentorium absent. Eyes dorsally with inner orbits arcuate, closest at middle; ocular canthus distinct; interocular distance 0.50-0.52 times as wide as head across eyes; interfacetal setae distinct. Antenna (Fig. 2B) 0.77-0.80 times as long as head capsule width, composed of 11 antennomeres; scape 1.65-1.70 times as long as pedicel; pedicel narrower than scape, barrel-shaped, 1.25-1.28 times as long as wide; antennomere 3 about 2.5 times longer than wide, and 2.15-2.30 times as long as antennomere 4; antennomere 4 as long as 5; antennomeres 6 and 7 quadrate. Antennal club consisting of 3 antennomeres, with two subterminal segments asymmetrical; penultimate antennomere as long as terminal one; terminal antennomere rounded apically. Anterior clypeal margin (Fig. 2E) distinctly emarginate with rounded lateral lobes and median area membranous. Labrum truncate at apex. maxillary cardo transverse with outer angle reaching slightly outside of mouth cavity; terminal palpomere 1.30-1.35 times as long as wide, expanded apically. mentum weakly transverse, 1.5 times as broad as long; anterior margin weakly arcuate; ventral surface with horseshoe-like impression; prementum transverse; ligula parallel-sided; labial palps separated by distance about equal to width of palpiger; apical palpomere as long and as broad as penultimate one; submentum distinct. PronotuM (Fig. 2F). with anterolateral angles rounded, scarcely produced anteriorly, not swollen with regular border; anterior and hind margin without border; lateral margin with entire border. Prothoracic hypomeron with weak, broad, concave area along anterior half of prothoracic lateral margin; notosternal suture weakly visible, simple; prosternal process ( Fig. 2G) 0.55 times as broad as longest coxal diameter, its surface with lateral carinae complete, convergent and joined anteriorly forming a triangle; prosternum in front of coxa about 0.45 times as long as coxal longitudinal diameter at the same position; anterior margin continuing as weakly arcuate line, much more posterior than anterior pronotal margin; procoxal cavity distinctly transverse, without visible bordering line.
PterotHorax. Anterior margin of mesoventrite with complete raised border (Fig. 2G); mesoventral process at median length of coxa 1.25-1.30 times as broad as corresponding coxal diameter; mesometaventrite articulation with suture visible; junction angulate posteriorly. scutellar shield transverse, triangular; surface punctate and setose. Elytra with sides subparallel; with lateral margins very narrow but entirely visible from above; surface with single size punctures (Fig. 2i), elytral epipleuron comparatively narrow, 1.5 times as wide as corresponding metaepisternum, incomplete apically ( Fig. 2A), inner margin with border area narrow throughout and border line fading before base of elytron. metaventrite with discrimen long but incomplete anteriorly; metaventral postcoxal lines distinctly separated at middle, laterally complete and recurved; metaepisternum with external process interlocking with fovea on elytron; metaepimeron indistinct.
MaLe terMinaLia and genitaLia (Figs 4C,. sternite iX with central part membranous (Fig. 4C); apodeme of male sternum iX with its apical half rod-like, base of spiculum broadly widened. Penis base with outer arm reduced, inner well developed; penis apex as in Fig. 5A-B. Parameres (Fig. 5C-D) articulated with phallobase, well developed, simple and separated, slightly longer than penis guide, with apices covered with long setae; penis guide simple, subtriangular in inner view, without additional processes, with acute apex and lateral sides symmetrical throughout and pointed apex; tegminal strut simple, slightly expanded at apex.
Female. not known.

Diagnosis
This species is most similar to R. amabilis Weise, 1918 and R. papuensis Tomaszewska, 2010, but can be distinguished from them by having a single apical spur on the mid and hind tibiae, and the prosternal process with carinae joined distinctly before the anterior prosternal margin and continuing anteriorly as a single carina (resembling an inverted wine glass). The shape of the prosternal carinae in R. atramentarius sp. nov. is similar to R. serratus sp. nov., but R. atramentarius sp. nov. differs from R. serratus sp. nov. by having a single apical spur on the mid and hind tibiae, the eyes with distinct interfacetal setae, ventrite 5 in male not emarginate at apex and an indistinct metaepimeron.

Etymology
The specific epithet means 'inky' in Latin and refers to the body colouration of this species.
Head (Fig. 1H). withdrawn into prothorax but with eyes partially visible externally; ventral antennal grooves distinctly circularly bent towards outer margin of eye. Eyes dorsally with inner orbits convergent, closer near vertex than anteriorly; ocular canthus extending slightly into eye; interocular distance 0.55 times as wide as head across eyes; interfacetal setae distinct. Antenna 0.70-0.73 times as long as head capsule width, composed of 11 antennomeres; scape swollen, 1.55-1.65 times as long as pedicel; pedicel distinctly narrower than scape, 1.20-1.25 times as long as wide; antennomere 3-2.72-2.75 times as long as wide, and about 2.25-2.50 times as long as antennomere 4; antennomere 4-1.30-1.33 as long as 5; antennomeres 5 and 6 quadrate, antennomeres 7 and 8 slightly obconical. Antennal club consisting of 3 antennomeres, with two subterminal antennomeres asymmetrical; penultimate antennomere distinctly shorter than terminal one; terminal antennomere distinctly elongate, rounded apically. Clypeus with anterior margin distinctly emarginate, with lateral rounded lobes and median area membranous (Fig. 3F). Labrum truncate at apex. maxilla with cardo transverse with outer angle reaching slightly outside of mouth cavity; terminal palpomere about as long as wide, weakly expanded apically. Labium with mentum strongly transverse, about 2 times as broad as long; anterior margin weakly arcuate; ventral surface with horseshoe-like impression; prementum transverse; ligula parallelsided; labial palps separated by distance about equal to width of palpiger; apical palpomere as long and as broad as penultimate one; submentum distinct. PronotuM (Fig. 3D). with anterolateral angles rounded, scarcely produced anteriorly, not swollen but with distinct groove near angles; anterior and hind margin without border; lateral margin with entire border. Prothoracic hypomeron (Fig. 3H) with broad, concave area along prothoracic lateral margin; notosternal suture distinct, simple; prosternal process 0.6 times as broad as longest coxal diameter, its surface with lateral carinae joined before anterior margin of prosternum and continuing anteriorly as a single carina; prosternum in front of coxa about 0.55 times as long as coxal longitudinal diameter at the same position; anterior margin continuing as weakly arcuate line, much more posterior than anterior pronotal margin; procoxal cavity distinctly transverse, without visible bordering line.
PterotHorax. Anterior margin of mesoventrite ( Fig. 3H) with complete raised border; mesoventral process at median length of coxa about 1.5 times as broad as corresponding coxal diameter; mesometaventrite articulation with suture visible; junction somewhat angulate posteriorly. scutellar shield transverse, triangular; surface punctate and setose. Elytra (Fig. 3A) with lateral margins narrow but entirely visible from above; elytral epipleuron ( Fig. 3B) incomplete apically, 2.7-3.0 times as wide as corresponding metaepisternum, inner margin with border area widening towards elytral base and border line upturned outwardly near base of elytron; elytral surface covered with middle size punctures, only along suture there is a row of smaller punctures (Fig. 2J). metaventrite with complete discrimen; metaventral postcoxal lines (Fig. 3H) distinctly separated at middle, recurved and laterally complete; metaepisternum with external process interlocking with fovea on elytron; metaepimeron indistinct.
Legs. with all trochanters angulately produced (Fig. 3B, H); fore tibia without spurs, mid and hind tibia with single apical spur; fore and mid tarsal claws in male appendiculate; metatarsal claws in male and claws in female with subquadrate basal tooth. aBdoMen (Fig. 4D). with five ventrites in both sexes; ventrite 1-1.6 times as long as ventrite 2; abdominal postcoxal lines separate medially, recurved and complete anteriorly, deep, posteriorly almost reach hind margin of ventrite 1; ventrite 5 in female distinctly longer than 4, with hind margin arcuate and smooth; ventrite 5 in male simply setose with hind margin narrowly truncate or scarcely emarginate medially; female sternite Viii with hind margin arcuate, tergite Viii rounded; hind margin of male sternite Viii emarginate (Fig. 4E), tergite Viii widely truncate apically.
MaLe terMinaLia and genitaLia (Figs 4F, 5e-H). male genital segment with sternite iX with central part membranous (Fig. 4F); apodeme of male sternum iX with its apex widened, and base of spiculum widened, partially submembranous with small sclerotized, lateral sclerites. Penis base with outer arm reduced, inner arm well developed; penis apex as in Fig. 5E-F. Parameres (Fig. 5G-H) articulated with phallobase, well developed, simple and separated, distinctly longer than penis guide, densely setose along at least half of their length, with apices covered with simple, long setae; penis guide simple, subtriangular, without additional processes, with lateral sides symmetrical and pointed apex; tegminal strut simple.

Diagnosis
This species is similar to R. amabilis Weise, 1918 and R. papuensis Tomaszewska, 2010, but it can be distinguished from them by having elytra with a distinct, oval area along the mid length of the elytral suture covered with only small punctures surrounded by rows of coarse macropunctures (similar to R. weiri Tomaszewska, 2010), and the prosternal process with carinae joined before the anterior prosternal margin and continuing anteriorly as a single carina. This shape of prosternal carinae is similar to that in R. atramentarius sp. nov., but R. serratus sp. nov. differs from it by lacking of tibial spurs, the eyes without interfacetal setae, ventrite 5 in the male with the posterior margin emarginate and by having distinct metaepimeron.

Etymology
The name of this species derives from the Latin and refers to the serrate outer surface of the penis guide.
Head (Fig. 1L). withdrawn into prothorax with eyes partially visible externally; ventral antennal grooves distinctly circularly bent towards outer margin of eye. Eyes dorsally with inner orbits convergent, closer near vertex than anteriorly; ocular canthus extending slightly into eye; interocular distance 0.53 times as wide as head across eyes; interfacetal setae indistinct. Antenna composed of 11 antennomeres, about 0.75 times as long as head capsule width; scape large, swollen, 1.55 times as long as pedicel; pedicel barrel-shaped, narrower than scape, 1.3 times as long as wide; antennomere 3-2.30 times as long as wide, and about 2.5 times as long as 4; antennomere 4-1.15 times as long as 5; antennomeres 5 and 6 quadrate, antennomere 7 obconical, at base about 0.75 times as wide as at apex and about 1.2 times as long as antennomere 6. Antennal club consisting of 3 antennomeres, with two subterminal segments asymmetrical; antennomere 9 as long as antennomere 10 and distinctly shorter than terminal antennomere; terminal antennomere distinctly elongate, rounded apically. Anterior clypeal margin distinctly emarginate, with rounded lateral lobes and with median area membranous. Labrum truncate at apex. maxilla with cardo transverse with outer angle reaching slightly outside of mouth cavity (Fig. 3G); terminal palpomere 1.1 times as long as wide, weakly expanded apically. mentum transverse, about 1.5 times as wide as long; anterior margin almost straight; ventral surface with horseshoe-like impression; prementum as long as broad; ligula parallel-sided; labial palps separated by distance about equal to width of palpiger; apical palpomere as long and as broad as penultimate one; submentum distinct.
PronotuM. with anterolateral angles rounded, not swollen, but with distinct groove near angles; anterior and hind margin without border; lateral margin with entire border. Prothoracic hypomeron (Fig. 3i) with broad, concave area along anterior half of prothoracic lateral margin; notosternal suture distinct, simple; prosternal process 0.6 times as broad as longest coxal diameter, its surface with carinae joined before apex and continuing anteriorly as single carina; prosternum in front of coxa about 0.65 times as long as coxal longitudinal diameter at the same position; anterior margin continuing as weakly arcuate line, much more posterior than anterior pronotal margin; procoxal cavity distinctly transverse, without visible bordering line.
PterotHorax. Anterior margin of mesoventrite ( Fig. 3i) with complete raised border; mesoventral process at median length of coxa about 1.20 times as broad as corresponding coxal diameter; mesometaventrite articulation with suture visible; junction angulate posteriorly. scutellar shield transverse, triangular, surface punctate and setose. Elytra with lateral margins narrow, but entirely visible from above; surface with distinct, oval area with small punctures along mid length of elytral suture surrounded by rows of coarse macropunctures (Fig. 3E). Elytral epipleuron incomplete apically, 2.5 times as wide as corresponding metaepisternum, inner margin with border area narrow throughout and border line fading before base of elytron. metaventrite coarsely punctate, with complete discrimen; metaventral postcoxal lines distinctly separated at middle, recurved and complete laterally; metaepisternum with external process interlocking with fovea on elytron; metaepimeron distinct, visible ventrally.
MaLe terMinaLia and genitaLia (Figs 4i, 5J-M). male genital segment with sternite iX with central part membranous (Fig. 4i); apodeme of male sternum iX rod-like, and base of spiculum widened, membranous. Penis base with outer arm obsolete, inner arm well developed; penis apex as in Fig. 5J-k. Parameres (Fig. 5L-m) articulated with phallobase, well developed, simple and separated, comparatively narrow, about 0.9 times as long as penis guide, with apices covered with simple setae; penis guide broad, without additional processes with outer margin serrate along apical half, widest at about apical sixth, with lateral sides sinuate but symmetrical throughout, with upturned apex; tegminal strut simple. An updated key to species of Rhyzobius from New Guinea (based on Tomaszewska, 2010) 11. Pronotal lateral margins distinctly swollen towards anterolateral angles of pronotum and with deep groove near angles; prosternal process with carinae joined before anterior margin of prosternum and continuing anteriorly as single carina .

Discussion
The New Guinean Rhyzobius fauna was represented until the present study by 11 species (Tomaszewska 2010). All of them are predominantly montane species, except R. papuensis, which can also be found in lowlands (< 1200 m a.s.l.). The three new species here described are also montane species and inhabit middle elevations. Rhyzobius albinos sp. nov. is a montane forest species occurring at altitudes between 1200 and 2200 m a.s.l. in forest types like "mixed lowland forest" and "lower-to mid-montane forest". Rhyzobius atramentarius sp. nov. was found at altitudes of 1200-1700 m a.s.l. in an elevational zone classified as "mixed lowland forest" and "lower montane forest", and R. serratus sp. nov. was found at an altitude of 1700 m a.s.l. in an elevational zone classified as "lower montane forest". Classification of elevational zones and altitudes corresponding to them according to Johns (1982) and Leponce et al. (2016).
Considering that 11 species of this genus were previously known from the whole island, the finding of three new species in this one place alone may indicate that the local fauna is only moderately known, and it is probable that more species will be found in the future at different localities.