Nitorus Telnov, 2007

Telnov, Dmitry, 2024, New species and records of Anthicidae Latreille, 1819 (Coleoptera) from Taiwan with a key to Asian Nitorus Telnov, 2007 species with gibbose pronotum, Zootaxa 5507 (2), pp. 285-312 : 310-311

Addition. Key to Asian species of Nitorus Telnov, 2007 with gibbose pronotum

This is the first attempt to list and key the species of Nitorus from Asian mainland and Sundaland with dorsally strongly gibbose and, in some species, saddle-like depressed pronotum. Proper identification is possible for both sexes, but the present key is focused primarily on males.

Several Asian Nitorus (for instance, N. philipinnensis (Pic, 1931) , N. sumatrae (Pic, 1894) etc.) are known to have slightly bigibbose pronotum (gibbosity is not prominent in lateral view). These species are not considered in the present key. Nitorus testaceitarsis (Pic, 1923) from Greater Sunda Islands is unknown to me. According to the original description (Pic 1923), base of pronotum is bituberculate in this species. However, it is unclear if the anterior pronotal lobe is gibbose or not and does the lateral pronotal constriction continues onto pronotal disc or not. I therefore decided not to include this species to the present key.

1 Pronotum in lateral view with distinct gibbosity on anterior, with or without another gibbosity on posterior lobe.......... 3

- Pronotum in lateral view with distinct gibbosity on posterior lobe only, anterior lobe slightly convex to flattened.......... 2

2 Lateral constriction continues onto pronotal dorsum forming moderately deep impression; head strongly constricted posterior to compound eyes, posterior head nearly tapered; dorsum uniformly brown with paler legs and antennae................................................................................................. N. peguensis ( Pic, 1913)

- Lateral constriction not or hardly continues onto pronotal dorsum; head posterior to compound eyes rounded in broad arc; forebody paler yellowish to rufous, each elytron with pale spot in postbasal impression area......................................................................... some Japanese specimens of N. trigibber (Marseul, 1876) ( Fig. 6C )

3 Pronotum in lateral view with distinct gibbosity on anterior and more or less strong gibbosity also on posterior lobe, lateral constriction continues onto pronotal dorsum in a form of saddle-like impression................................... 4

- Pronotum in lateral view with gibbosity on anterior lobe only; posterior lobe not gibbose, lateral constriction does not continue onto pronotal dorsum.......................................................... N. dromedarius ( Telnov, 2005)

4 Pronotum in lateral view with anterior and posterior pronotal gibbosities nearly equally high, gibbosities apically tapered, not semicircular (broadly rounded).......................................................................... 5

- Pronotum in lateral view with anterior gibbosity significantly stronger than posterior or both gibbosities semicircular (not tapered apically)..................................................................................... 10

5 Dorsal head minutely punctate; lateral margins of anterior pronotal lobe broadly rounded in dorsal view; width ratio of anterior to posterior pronotal lobe about 1.3 or less; elytra slightly convex or nearly flattened in dorsal aspect, postbasal transverse impression distinct; elytron with more or less wide pale transverse spot or fascia in postbasal impression area............ 7

- Dorsal head with distinct punctures; lateral margins of anterior pronotal lobe expanded medially, subangulate in dorsal view; width ratio of anterior to posterior pronotal lobe about 1.4 or more; elytra distinctly convex in dorsal aspect, postbasal transverse impression not indicated; elytron without pale transverse spot or fascia in postbasal impression area, maximum dark reddish brown at base but not contrastingly paler than rest of elytra.................................................... 6

6 Dorsal head with large deep punctures; width ratio of anterior to posterior pronotal lobe about 1.5; lateral sides or pronotum in constriction area with distinct longitudinal subparallel wrinkles; aedeagus as in fig. 18, apex of median lobe narrowly pointed.............................................................................. N. sathulaz sp. nov.

- Dorsal head with distinct but rather moderate and shallow punctures; width ratio of anterior to posterior pronotal lobe about 1.4; lateral sides or pronotum in constriction area not or indistinctly longitudinally wrinkled; aedeagus not as in fig. 18, apex of median lobe less slender, rounded................................................. N. monstrosicollis (Pic, 1901)

7 Pronotum in lateral view with anterior gibbosity somewhat stronger (stronger elevated or/and larger) than posterior or both gibbosities nearly equally strong; head somewhat constricted at base; aedeagus not as in figs 2F–I & 7................. 9

- Pronotum in lateral view with posterior gibbosity somewhat stronger elevated than anterior; aedeagus as in figs 2F–I or 7... ................................................................................................... 8

8 Head somewhat constricted at base; aedeagus as in fig. 2F–I.................................... N. mediator sp. nov.

- Head rounded in broad arc posterior to compound eyes; aedeagus as in fig. 7................ N. trigibber (Marseul, 1876)

9 Pronotum in lateral view with anterior gibbosity broad, obtuse angulate; posterior gibbosity slightly less strongly elevated compared to anterior; dorsum generally uniformly brown, narrow pale transverse fascia on elytra in postbasal impression area............................................................................. N. bigibbosus ( Pic, 1913)

- Pronotum in lateral view with anterior gibbosity rather slender, subacutely angulate; posterior gibbosity same strongly elevated as anterior; pronotum paler than head and elytra, elytra with rather broad pale transverse fascia in postbasal impression area................................................................... N. bidentatus (Pic, 1901)

10 Elytra uniformly dark or with pale transverse band or spot in postbasal impression area............................ 12

- Elytra largely pale yellowish rufous with darkened median area or dark with two pale areas on each elytron—postbasal and postmedian................................................................................................. 11 [some specimens of N. arcuatus (Krekich-Strassoldo, 1914) are similarly coloured, but aedeagus is different, protibia without modifications, head base broadly rounded, Pronotum in lateral view with two semicircular gibbosities]

11 Male protibia without modifications; antennomeres 6‒8 not modified (widened / flattened); aedeagus trident-shaped apically, as in fig. 4F–H............................................ N. mediomaculatus ( Pic, 1913) stat. restit., comb. nov.

- Male protibia distinctly sinuous; antennomeres 6‒8 widened and somewhat dorso-ventrally flattened; aedeagus not as in fig. 4................................................................ N. lepidus (Krekich-Strassoldo, 1913)

12 Elytra uniformly coloured, without pale spots or bands....................................................... 13

- Elytra with more or less prominent pale spot or transverse band in postbasal transverse impression area................ 14

13 Head distinctly constricted posterior to compound eyes; pronotum slender, about as wide as head between compound eyes, in dorsal view hourglass-shaped, anterior lobe significantly wider than posterior; metatibia not modified (widened or thickened)....................................................................... N. subconiceps (Pic, 1914)

- Head rounded posterior to compound eyes; pronotum in dorsal view either subcylindrical with bulged anterior lobe, not hourglass-shaped, anterior lobe less strongly wider than posterior; metatibia slightly widened........ N. collaris (Pic, 1901)

14 Pronotum or entire dorsal forebody distinctly paler than elytra; two or several basal antennomeres distinctly paler than rest of antenna............................................................................................ 15

- Dorsal forebody about the same colour as elytra; basal (one) antennomere distinctly paler than rest of antenna.......................................................................................... N. luteofasciatus (Pic, 1922)

15 Posterior lobe of pronotum entire, not bilobate; profemur yellowish, protibia entirely or at least medially dark; compound eye comparatively smaller; elytra slightly convex with moderately prominent postbasal transverse impression; metatibia slightly arched................................................................ N. arcuatus (Krekich-Strassoldo, 1914)

- Posterior lobe of pronotum bilobate (with a short median longitudinal impression and a lateral gibbosity either side of it); protibia not contrastingly darker than profemur; compound eye comparatively larger; elytra flattened, without or with vaguely defined postbasal transverse impression; metatibia not modified....................... N. bifidus (Krekich-Strassoldo, 1929) and N. gibber ( Bonadona, 1981) , likely conspecific, the differential diagnosis in Bonadona (1981) is suboptimal.

Figures

FIGURE 6. Nitorus trigibber (Marseul, 1876). A—♀ from ‘14km W of Chihshang’, habitus, dorsal view; B—ditto, lateral view; C—♀ from ‘Japan’ collected by Lewis, forebody, lateral view [not to scale].