Caledomus, Kirejtshuk & Kovalev, 2017

Kirejtshuk, Alexander G. & Kovalev, Alexey V., 2017, Caledomus gen. nov., a new cillaeine genus (Coleoptera, Nitidulidae) from New Caledonia and taxonomic notes, Zootaxa 4277 (3), pp. 443-450 : 444-446

Caledomus gen. nov.

Type species: Caledomus extraordinarius sp. nov.

Etymology. The name of this genus is formed from the name of the island of its origin (New Caledonia— “ Caledo ”) and last three letters of generic name Adocimus (“ mus ”). Gender masculine.

Description. Body medium to large sized (7.3 – 8.3 mm), narrow and elongate, weakly convex to subflattened dorsally and more convex ventrally. Integument with distinct, medium-sized and moderately dense punctures, smoothly microreticulate; elytra with rather large and dense subcontiguous punctures arranged into longitudinal rows in moderately deepened furrows, convex interspaces with one longitudinal row of very fine punctures; head and thorax without pubescence, but posterior parts of hypomeron with some short hairs, elytra with very short hairs associated with small punctures on convex interspaces between longitudinal rows, dorsal and ventral abdominal sclerites with sparse and short hairs.

Head subflattened and gradually narrowed to base, moderately projecting anteriorly; with moderately large and extremely finely faceted eyes located at head midlength (not shifted anteriorly), temples gently narrowing posteriorly, labrum arcuately rounded at anterior edge and with clear median suture; mandibles stout with tridentate apices and dilated laterally; antennal grooves with distinct inner and outer margins, arcuately curved posteriorly, smallest distance between them at level of posterior edge of eyes; mentum strongly transverse and widening anteriorly, with anterior lateral angles feebly projecting anteriorly; pregenal process at wide hypostomal sinus moderately narrow and subrectilinear. Terminal maxillary and labial palpomeres subcylindrical to subconical and somewhat longer than wide. Antenna with 11 antennomeres, antennomere 3 markedly longer than antennomere 2, 3-segmented club compact and slightly compressed dorsoventrally. Pronotum transverse, with subrectilinear anterior margin, and also with more or less subarcuate lateral and posterior margins, subflattened on disc and gently sloping at explanate sides, all angles rounded. Scutellar shield subpentagonal. Elytra with transversely truncate apices, leaving last three abdominal segments completely exposed, sides moderately steeply sloping and narrowly bordered, lateral carinae clearly visible from above. Laterosternites rather wide at base, narrowing posteriorly to narrowest place at anterior third and then subrectilinearly widening. Spiracles of two preapical abdominal segments elongate oval, somewhat more than twice as long as wide. Three last tergites medially convex and weakly widely depressed at sides. Male pygidium about as long as wide, widely emarginate at smooth (not crenulate) apex. Male anal sclerite in dorsal view more or less exposed posteriorly from under pygidial posterior margin, deeply excised at posterior edge, with a deep funnel-shaped invagination in the middle of posterior side, but without crenulations along posterior edge. Female pygidium somewhat shorter than wide, widely rounded to subtruncate at apex, without clear crenulations on posterior margin.

Prosternum with a very short collar; medially elevated and somewhat isolated; process subflattened, very slightly curved along procoxae and strongly widened at truncate apex. Pro- and metacoxae moderately, mesocoxae widely separated. Mesothorax medially flattened, at sides with distinctly isolated paramedial depressions for receiving mesofemora. Metaventrite with a distinct median suture (discrimen) in posterior three-fourths, its anterior edge almost straight and posterior edge between coxae arcuately excised. Metepisternum (metanepisternum) with rectilinear sides. Each of abdominal ventrites 1 and 2 much shorter than each of ventrites 3 and 4; hypopygidium longest. Epipleuron about as wide as metepisternum and markedly narrower than antennal club, gradually narrowed distally, moderately elevated laterally. Male hypopygidium somewhat shorter than long, very widely rounded before subtruncate apex and with crenulate apical edge. Female hypopygidium very widely rounded before subtruncate apex and without clear crenulations along apical margin.

Legs more or less of usual shape for many cillaeines. Tibiae subtriangular, at apex somewhat wider than antennal club and with very short spurs. Femora rather wide and unmodified, with convex anterior and posterior edges. Tarsi with rather widely lobed tarsomeres 1 – 3, protarsi wider than meso- and metatarsi.

Male anal sclerite (“tergite 8”) as in Fig. 7 . Aedeagus moderately sclerotized and as in Figs. 8–9 . Ovipositor as in Fig. 10 , short and blunt apex of inner lobes of gonocoxites with pair of paramedian incisions (each incision between stylus and ovipositor apex), styli flat, very short and wide.

Composition. Only the type species.

Diagnosis. Caledomus gen. nov. is a member of the Adocimus -complex ( Kirejtshuk & Kovalev 2016: Adocimus Murray, 1864 , Allenipeplus, Brittonoma nom. nov. and Ithyphenes Murray, 1864 (including Platynema Ritsema, 1885 ) and particularly similar to Adocimus by the general appearance, structure of antennal club, outline of pronotum, shape of sclerotized lobes of ligula, mentum, pregenal processes, prosternal process, thoracic depressions for receipt of femora, and some other external characters, although these genera are rather distinct in the following characters:

Caledomus gen.nov.

- most of integument with moderately coarse, moderately dense and deep punctures;

- elytra with longitudinal rows of coarse subcontiguous punctures in furrows, and interspaces between them with a row of very fine and rather sparse punctures; with longitudinal rows of short hairs associated with fine punctures;

- antennomere 3 markedly longer than antennomere 2;

- antennal grooves very clear, i.e. well depressed and with distinct inner and outer margins;

- pregenal process subrectilinear and parallel (not convergent anteriorly);

- pronotal sides subexplanate and transparent, with very sharp lateral carina;

- laterosternites narrowed before middle and widened at apex;

- sclerites of last abdominal segment (pygidium and hypopygidium) almost as wide as long or only slightly wider than long;

- male pygidium widely emarginate at posterior margin;

- anal sclerite deeply and widely excised at apex, with a deep funnel-shape invagination in the middle of posterior side, without crenulations along posterior edge;

- female pygidium widely rounded to subtruncate at apex and without visible crenulations along posterior edge;

- meso- and metatibiae subtriangular (not curved), without short and stout setae;

- tibial spurs stout and very short;

- ovipositor with short and blunt apex, and with a pair of subapical paramedian incisions at apex ( Fig. 10 );

Adocimus

- most of integument with rather fine, very sparse and shallow punctures;

- elytra with uniform, diffuse fine and sparse punctation, at most with trace of longitudinal arrangement and without furrows; without pubescence;

- antennomere 3 not longer than antennomere 2;

- antennal grooves unclear, i.e. slightly depressed and without distinct inner and outer margins;

- pregenal process curved and convergent anteriorly (not subrectilinear);

- pronotal sides without explanation and not transparent, with rather obliterated lateral carina;

- laterosternites of the exposed abdominal segments narrowing posteriorly (not widened at apex);

- sclerites of last abdominal segment (pygidium and hypopygidium) almost twice as wide as long;

- male pygidium widely convex at posterior margin;

- anal sclerite widely rounded at apex and distinctly crenulate along posterior edge;

- female pygidium widely rounded to subtruncate at apex and with clear crenulations along posterior edge;

- all tibiae curved and widened mostly at apex, meso- and metatibiae with short and stout setae;

- tibial spurs stout and moderately long;

- ovipositor with simple, moderately long and acuminate apex, and without paramedian incisions at apex.

In addition to the very distinct and rather deep longitudinal furrows on elytra, wider and more subparallel-sided antennal club, subpentagonal scutellar shield and lack of crenulations along the posterior margin of the male anal sclerite and female pygidium, and also the shape of apices of sclerites of the last abdominal segment and very peculiar structure of the ovipositor, Caledomus gen. nov., differs also from:

- Allenipeplus in the wider body; subflattened dorsum; regular punctation and pubescence on elytra; usual position of eyes (not shifted anteriorly); peculiar shape and explanate sides of pronotum; laterosternites of the preapical abdominal segments with curved inner edge and widened at apex; longer, slightly convergent, arcuate and shallow antennal grooves; prosternal process strongly widened before truncate apex; widely separated mesocoxae; subtriangular meso- and metatibiae without two rows of stout setae;

- Brittonoma nom. nov. in the subflattened dorsum; regular punctation and pubescence on elytra; head without V-shaped depression in the anterior part; peculiar shape and explanate sides of pronotum; usual position of eyes (not shifted posteriorly); elongate terminal labial palpomere; longer, slightly convergent, arcuate and shallow antennal grooves, wider and shorter tibiae (and legs in general);

- Ithyphenes (including Platynema ) in the truncate anterior margin of frons; simple labrum with contiguous outline of its anterior margin; usual position of eyes (not shifted anteriorly), distinct antennal grooves, rather wide and deep hypostomal sinuses, distinct paramedian depressions on mesoventrite; moderately separated (not widely) metacoxae; less widened femora; less triangular tibiae; much wider and shorter tarsi.

The male anal sclerite of Caledomus extraordinarius sp. nov. is somewhat similar to that in some (mostly undescribed) species of Brittonoma nom. nov. from the Papuan Province and Cillaeus Laporte, 1835 from the Afro-Madagascan areas and some members of the latter demonstrate a significant similarity in general appearance to the new species. Nevertheless, the new species and the representatives of Brittonoma nom. nov. can be distinguished by the abovementioned characters, while some species described as members of Cillaeus (including type species - Cillaeus castaneus Laporte, 1835 ) which are similar to Caledomus extraordinarius sp. nov., however the latter differs from them in the characters of the head (pregenal processes wider and more projecting anteriorly, shape of mentum and hypostomal sinuses), and also in the widely rounded anterior angles and clearly explanate sides of pronotum, subpentagonal scutellar shield, exposed laterosternites clearly widened posteriorly, presence of a collar of the anterior edge of prosternum, elevated median part of prosternum, concavity at the middle of hypopygidium of both sexes and structures of genitalia of both sexes.

Note. The group Ithyphenes (including Platynema ) is most diverse, possessing some characters diagnostic for other genera of the complex: elytral sculpture from diffuse to double with longitudinal rows, variable shape of the head, pronotum, elytra and dorsal sclerites of abdomen.

Figures

FIGURES 7 – 11. Caledomus extraordinarius gen. et sp. nov. (“ N. New Caledonia, Tinchialit, 2,020 ft, 21. ix- 3. x. 1949, L. E. Cheesman, B. M. 1950 - 1 ”), male, holotype, BMNH (Figs. 7, 9); female, paratype, ZIN (Figs. 10, 11). 7: male anal sclerite and spiculum gastrale, ventral; 8: tegmen, ventral; 9: penis trunk, dorsal; 10: ovipositor, ventral; 11: spiculum ventrale, ventral. Scale bars = 0.5 mm: a, for Figs. 7 – 10; b, for Fig. 11.