Dentirotacorimus Yoshida & Hirowatari

Yoshida, Takahiro, Hirowatari, Toshiya & Hashim, Rosli, 2017, A new genus of Silvaninae (Coleoptera: Silvanidae) with two new species from the Malay Peninsula, Zootaxa 4258 (4), pp. 365-374 : 366-367

Dentirotacorimus Yoshida & Hirowatari , gen. nov.

Type species: Dentirotacorimus reticulatus Yoshida & Hirowatari , sp. nov.

Description. Body oval and depressed, covered with short, thick and golden setae. Head without ventral antennal grooves; head prominent at genal region (front of eyes) laterally; temples absent; labrum completely covered by clypeus; antenna ( Figs 2 A, 4A) with 11 antennomeres, with 2-segmented club with antennomere 10 long; mandibles ( Figs 3 B,C) strongly protruding at apices with a tooth on each inner margin and a tooth ventrally, outer dorsal lateral areas laterally explanate; maxilla ( Fig. 3 D) with lacinia and galea; maxillary palpi 4-segmented; palpomere 1 small; palpomere 4 long and conical; labium ( Fig. 3 E) expanded anterolaterally; labial palpi 3- segmented; palpomere 1 stout. Pronotum with anterior angles strongly protruding anterolaterally along eyes, with six conspicuous lateral teeth; 1st tooth larger and more rounded than remaining teeth; intercoxal process of mesoventrite narrowed posteriorly and widened around apex. Scutellar shield with a transverse furrow. Legs ( Figs 2 B, 4B) short and somewhat flattened; metacoxa ( Figs 2 B, 4B) oblong, with transverse ridge; femora inflated; tibiae widening distally; tarsi ( Figs 2 C, 4C) 5-segmented, tarsomere 3 not incrassate, tarsomere 5 long; claws simple. First abdominal ventrite ( Figs 2 D, 4D) with femoral line. Elytra oval, obliquely truncate at apices; with four sets of a row of setiferous tubercles followed by two rows of punctures; lateral margins widely flattened, dorsally with many setiferous tubercles, with many denticles on anterior lateral margins. Male with sternite VIII ( Figs 2 E, 4E) with paired plates connected by membrane, with a very long seta at posterior angle, and a mediumlength seta around each posterior angle; spiculum gastrale Y-shaped, distal branches membranous, basal branches connected by membrane; median lobe ( Figs 2 G, 4G) with long median strut, ventrally partly covered with setae of various length; parameres ( Figs 2 H, 4H) long and thin, more or less fused with phallobase, with a few long setae on each apex; phallobase ( Figs 2 H, 4H) narrowed anteriorly.

Distribution. Malaysia.

Etymology. The genus name is a combination of “dentirota” and the genus “ Corimus ”. ”Dentirota” is Latin for “toothed wheel”. The well-extended teeth, like those of a gear wheel, laterally on the pronotum are one of the remarkable morphological characters of the new genus.

Remarks. The body shape of this genus, the depressed body, and the explanate margins, are consistent with the typical morphology of Corimus -like genera. However, this genus is easily distinguished by the combination of the following character states ( Table 1): antenna with 11 antennomeres (9 antennomeres in Corimus ), antennal club 2- segmented (3-segmented in Afrocorimus and Metacorimus ), genal region prominent (not prominent in Acorimus and Metacorimus , angulate in Afrocorimus ), ventral antennal grooves absent (present in Acorimus and Metacorimus ), pronotum toothed laterally (undulating in Corimus and Metacorimus ) and tarsomere 3 simple (incrassate in Corimus and Afrocorimus ). The elongate parameres of this genus are also characteristic and similar to those of Corimus ( Table 1).

Figures

FIGURE 2. Dentirotacorimus reticulatus sp. nov., male. A, Right antenna; B, right hind leg, ventral view; C, metatarsus, ventral view; D, abdominal ventrites; E, eighth and ninth abdominal segments, ventral view; F, internal sac, ventral view; G, median lobe, ventral view; H, tegmen, ventral view. Scale: 0.2 mm for A – C, E – H and 0.4 mm for D.

FIGURE 3. Mouth parts of Dentirotacorimus reticulatus sp. nov. A, Labrum, dorsal view; B, C, right mandible, ventral view (B) and dorsal view (C); D, right maxilla, dorsal view; E, labium, ventral view. Scale: 0.1 mm.