Promethis tuberculata, Cheong, 2025

Cheong, Loong Fah, 2025, On nomenclature and taxonomy of some Carabidae and Tenebrionidae from Singapore, with descriptions of new species of the genera Uloma Dejean, 1821 and Promethis Pascoe, 1869, Raffles Bulletin of Zoology 73, pp. 233-242 : 239-240

Promethis tuberculata , new species

( Figs. 4A- E )

Type specimens. Holotype: Male, Singapore: Chestnut, coll. L. F. Cheong & Y. W. Cheong, 13 May 2014 . Paratypes: 1 male, Singapore: Bt. Timah Main Road , coll. L. F. Cheong, 21 September 2021 . 1 male, Singapore: Chestnut , coll. L. F. Cheong, 30 November 2020 ; 1 female, ditto . 1 female, ditto, 11 November 2019 .

Measurements. Male (n = 3): BL: 19.5-22.6 mm; BW: 7.4-9.1 mm; PW/PL: 1.22-1.29; EL/EW: 1.56-1.68. Female (n = 2): BL: 19.2-19.5 mm; BW: 7.2-7.4 mm; PW/PL: 1.25-1.29; EL/EW: 1.72-1.76.

Description. Male. Elongate, black, matt. Head with punctures fine, coarser near frontoclypeal suture; clypeus shallowly emarginate at anterior margin; frontoclypeal suture finely incised but not forming deep groove; ocular ridges distinctly elevated, reaching more or less the rear edges of eyes. Antennae short, reaching middle of pronotum. Mentum obtrapezoidal, with pronounced, dense, erect, yellow moustache. Pronotum widest at middle; lateral margins reflexed, slightly sinuate before base, with beads gradually becoming narrow to very narrow forward until just before anterior corners, thence the margins weakly emarginate ( Fig. 4B ); all margins distinctly beaded; apical margin interrupted in middle; disk densely and finely punctate, with basally keeled median line, interspaces between punctures weakly microreticulate. Propleura nearly smooth, shallowly rugulose; prosternal process broad, flat, bisulcate, basal portion with moderately dense golden hairs, elsewhere with sparsely scattered short golden hairs. Elytra striate-punctate; intervals convex, slightly shagreened, with microscopic punctures. Metaventrite nearly smooth, with fine punctures or microgranules each of which bears very short hair; disc covered by dense golden pubescence in the middle, with three clusters of elongate granules on each side of midline in posterior half ( Fig. 4C ). Abdominal ventrites with fine minute punctures or microgranules each of which bears very short hair; 5th ventrite furrowed apically. Protibia strongly bent at apical fourth, densely pubescent in apical sixth ( Fig. 4D ), with a blunt broadening in the basal region. Aedeagus ( Fig. 4E ) slightly curved; parameres gradually narrowed apicad from base, 0.75 times as long as basal piece.

Female. Pubescence on prosternal process and metaventrite shorter than male; metaventrite without clusters of elongate granules; protibia not strongly bent at apex, with pubescence there shorter and less dense than male.

Distribution. Singapore.

Diagnosis. The widely distributed Promethis excisa ( Gebien, 1914) (recorded from Malaysia, Singapore, Sumatra, Borneo, Sulawesi, Philippines) shares with P. tuberculata , new species, the trait of having their broadly beaded lateral margins of pronotum becoming very finely beaded before the anterior corners so that a shallow emargination is observed on the lateral margins. P. excisa differs from P. tuberculata , new species, as follows: (1) anterior corners of pronotum more distinctly emarginate; (2) frontoclypeal suture with a deep groove; (3) male protibia sharply edged on outer margin near apex, with two blunt broadenings basally; (4) male mesotibia suddenly widened just before apex; (5) metaventrite glabrous in females (not described for males); (6) aedeagus more strongly curved; parameres almost parallel-sided at base, only narrowing in apical third.

Remarks. P. tuberculata , new species, belongs to the P. excisa group (sensu Kaszab, 1988a) on account of its mentum with pronounced, dense, yellow moustache, and 5th abdominal ventrite furrowed apically, among other characters. Among the extant four species of this group, P. plicifrons ( Gebien, 1918) from Malaysia and Singapore is most readily identified by its strikingly short antennae, the presence of a granule on the metaventrite between the mesocoxae in males, and the strikingly flattened mesotibiae in males. The remaining species in this group, together with the new species P. tuberculata , new species, all reach couplet 254 in the key of Kaszab (1988a) due to the absence of the aforementioned characters of P. plicifrons . P. tuberculata , new species, and P. excisa are then separated from the rest by the distinctive emargination on the lateral margins of pronotum just before the anterior corners. In other words, P. tuberculata , new species, would be inserted into the key at couplet 254, which has to be altered as follows:

254 (255) Lateral margins of pronotum with bead narrowed to very narrowed forward and interrupted far before the anterior corners, before which the margins are more or less distinctly emarginate.

254a (254b) Frontoclypeal suture bearing a deep groove; male protibia strongly curved at about apical third, with two blunt broadenings basally and a sharp edge at the outer margin near apex; male mesotibia suddenly widened just before apex; metaventrite glabrous in females ..... P. excisa ( Gebien, 1914)

254b (254a) Frontoclypeal suture finely incised but without deep groove; male protibia strongly bent at apical fourth, with a blunt broadening basally; male mesotibiae not suddenly widened near apical portion; metaventrite with golden pubescence, males with three clusters of elongate granules on each side of midline in posterior half .............................. P. tuberculata , new species

255 (254) Lateral margin of pronotum with bead not interrupted at the anterior corner, beading continuously into that of anterior margin.

The comparative diagnosis above is partly based upon my examination of the type material of P. excisa in NHMB. The holotype of P. plicifrons cannot be located; I have instead studied the photographs of a HNHM specimen identified by Kaszab as P. plicifrons (photographs kindly provided to me by György Makranczy of HNHM).

Collecting circumstances. Encountered in rotting wood.

Etymology. The specific name refers to the coarse granules that occur on the metaventrite of the males.

Figures

Fig. 4. A–E, Promethis tuberculata, new species, holotype, male. A, habitus dorsal; B, lateral margin of pronotum strongly narrowed before anterior corner (arrow); C, metaventrite with three clusters of granules (arrows); D, right protibia; E, aedeagi, dorsal (left) and lateral (right) views.