Rhyzobius atramentarius, Czerwiński & Szawaryn & Tomaszewska, 2020

Czerwiński, Tomasz, Szawaryn, Karol & Tomaszewska, Wioletta, 2020, Three new species of the genus Rhyzobius Stephens, 1829 from New Guinea (Coleoptera: Coccinellidae: Coccidulini), European Journal of Taxonomy 692, pp. 1-17 : 7-11

Rhyzobius atramentarius sp. nov.

urn:lsid:zoobank.org:act:DF580E82-B342-4539-A42C-EB783E34A9FA

Figs 1 E–H, 2J, 3A–B, D, F, H, 4D–F, 5E–I

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.

Material examined

Holotype

NEW GUINEA • ♂; Madang Province , Mt Wilhelm, Bananumbo; 5º45ʹ33.4ʺ S, 145º14ʹ08.2ʺ E; 1700 m a.s.l.; 7–9 Nov. 2012; “06695-CoCocc Ibisca Niugini 2012”; FIT-MW1700-L-7/8-d14; plot 12, order 5212; MNHN.

Paratypes

NEW GUINEA – Madang Province • 1 ♂; same collection data as for holotype; 1–3 Nov. 2012; “06678-CoCocc Ibisca Niugini 2012”; FIT-MW1700-L-4/8-d08; plot 12, order 10222; MNHN • 1 ♀; same collection data as for holotype; 26–29 Oct. 2012; “02446-CoCocc Ibisca Niugini 2012”; FIT- MW1700-B-2/8-d03; plot 2, order 4308; MNHN • 1 ♂; Mt Wilhelm ; 1200 m a.s.l.; 3–5 Nov. 2012; “18842-CoCocc Ibisca Niugini 2012”; FIT-MW1200-R-5/8-d10; plot 18, order 3059; MIZ .

Type locality

Papua New Guinea, Madang Province, Mt Wilhelm, Bananumbo.

Description

MEASUREMENTS. Length 2.00– 2.35 mm; TL/EW = 1.17; PL/PW = 0.50; EL/EW = 0.90–1.00.

BODY ( Figs 1 E–G, 3A–B). Broadly oval, strongly convex dorsally, hemispherical, winged; black or blackish brown, predominantly with bluish metallic sheen; antennae, mouthparts, tarsi, ventrites 2–5 and ventrite 1 partially, brown. Dorsum with double pubescence consisting of appressed setae and sparse darker stiff bristles; dorsal pubescence forming weak wavy pattern on elytra; sparse elytral bristles present on lateral margins and apices only.

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 , 5 E–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. 5 E–F. Parameres ( Fig. 5 G–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.

FEMALE GENITALIA ( Fig. 5I ). Proctiger (T10) reduced, small, submembranous; styli strongly reduced and hardly visible; infundibulum absent; sperm duct short, uniform in diameter, spermatheca without clear nodulus and ramus, spermathecal accessory gland adjacent to sperm duct.

Distribution

Papua New Guinea: Mt Wilhelm.

Figures

Fig. 1. Habitus of new species of Rhyzobius spp. (holotypes). A–D. R. albinos sp. nov., ♂ (MNHN). E–H. R. atramentarius sp. nov., ♂ (MNHN). I–L. R. serratus sp. nov., ♂ (MNHN). A, E, I. Dorsal view. B, F, J. Ventral view. C, G, K. Lateral view. D, H, L. Frontal view. Scale bars = 0.5 mm.

Fig. 3. SEM images of Rhyzobius spp. (holotypes). A–B, D, F, H. R. atramentarius sp. nov., ♂ (MNHN). C, E, G, I. Rhyzobius serratus sp. nov., ♂ (MNHN). A. Habitus, dorsal. B–C. Habitus, ventral. D. Pronotum. E. Details of elytral punctation. F–G. Head, ventral. H–I. Pro-, meso- and metathorax, ventral. Scale bars: A–C = 1.0 mm; D–E, H– I = 0.5 mm; F = 0.4 mm; G = 0.3 mm.

Fig. 2. SEM images of Rhyzobius spp. (holotypes). A–I. R. albinos sp. nov., ♂ (MNHN). J. R. atramentarius sp. nov., ♂ (MNHN). A. Habitus, ventral. B. Antenna. C. Protarsal claws. D. Hind tarsal claws. E. Head, ventral. F. Pronotum. G. Pro-, meso- and metathorax, ventral. H. Abdomen, ventral. I–J. Details of elytral punctation. Scale bars: A = 1.00 mm; B = 0.2 mm; C–D = 0.1 mm; E–F = 0.3 mm; G = 0.4 mm; H–J = 0.5 mm.

Fig. 4. Abdomens and male terminalia of Rhyzobius spp. A–C. R. albinos sp. nov. D–F. R. atramentarius sp. nov. G–I. R. serratus sp. nov. A, D, G. Abdomen. B, E, H. Abdominal segment VIII, ventral. C, F, I. Male genital segment, dorsal. Scale bars: A, D, G = 0.5 mm; B–C, E–F, H–I = 0.2 mm.

Fig. 5. Male and female genitalia of Rhyzobius spp. A–D. R. albinos sp. nov. E–I. R. atramentarius sp. nov. J–M. R. serratus sp. nov. A, E, J. Penis, lateral. B, F, K. Apex of penis. C, G, L. Tegmen, inner view. D, H, M. Tegmen, lateral. I. Female genitalia. Scale bars: 0.2 mm.