Scydmobisetia dentipes Jałoszyński & Bai, 2020

Jałoszyński, Paweł, Bai, Ming & Wang, Bo, 2020, A new species of the extinct mid-Cretaceous genus Scydmobisetia Jałoszyński & Yamamoto (Coleoptera, Staphylinidae, Scydmaeninae), Zootaxa 4802 (3), pp. 582-586 : 583-585

publication ID

https://doi.org/ 10.11646/zootaxa.4802.3.12

publication LSID

lsid:zoobank.org:pub:E4C036B4-D40C-45AE-B5E0-34408CC21423

persistent identifier

https://treatment.plazi.org/id/75175853-C908-FFFE-FF6A-FC71D132FE44

treatment provided by

Plazi

scientific name

Scydmobisetia dentipes Jałoszyński & Bai
status

sp. nov.

Scydmobisetia dentipes Jałoszyński & Bai View in CoL sp. n.

( Figs 1–12 View FIGURES 1–6 View FIGURES 7–12 )

Type material. Holotype: ♂, Myanmar, Hukawng Valley, Kachin State, lowermost Cenomanian, Upper Creta- ceous, inclusion in amber, collection No. NIGP173185 View Materials NIGP).

Diagnosis. Male with long tooth-like projection on proximal, ventral margin of each profemur and tuft of conspicuously long, undulating setae on subapical region of mesotibia; profemora slightly thickened in relation to meso- and metafemora.

Description. Body of male ( Figs 1–3 View FIGURES 1–6 , 7–10 View FIGURES 7–12 ) slender and flattened, dark brown, covered with vestiture of setae slightly lighter than cuticle. BL 1.75 mm.

Head ( Figs 4–5 View FIGURES 1–6 , 7–10 View FIGURES 7–12 ) broadest at small and weakly convex eyes, HL 0.28 mm, HW 0.33 mm; mandibles ( Fig. 11 View FIGURES 7–12 ) long and slender, each with two sharp preapical mesal teeth; tempora in dorsal view about twice as long as eyes; vertex strongly transverse, weakly convex; frons confluent with vertex, flattened between weakly elevated supra- antennal tubercles. Punctures on vertex and frons distinct, dense but shallow; setae short, dense suberect; posterior margin of vertex with a pair of long, suberect bristles (one broken off in the studied specimen). Antennae ( Figs 5 View FIGURES 1–6 , 9–10 View FIGURES 7–12 ) long and slender, AnL 0.80 mm; antennomeres I–VII each elongate (I–V strongly so), VIII indistinctly longer than broad, IX and X each about as long as broad, XI about 1.7 × as long as broad, with asymmetrical apical half.

Pronotum ( Figs 4 View FIGURES 1–6 , 7–8 View FIGURES 7–12 ), broadest near anterior third; PL 0.50 mm, PW 0.43 mm. Anterior and lateral margins in anterior half rounded together, sides in posterior half sinuate, posterior corners nearly right-angled but blunt, posterior margin weakly arcuate; pronotal base with lateral pair of elongate, subtriangular impressions (median basal impression visible in Fig. 4 View FIGURES 1–6 is not perfectly at middle and seems to be an artifact of preservation). Punctures on pronotum dense but shallow and small; setae dense, short, suberect.

Elytra ( Figs 1–3 View FIGURES 1–6 , 7–10 View FIGURES 7–12 ) slightly flattened, together slightly rhomboidal, broadest distinctly in front of middle; EL 0.98 mm, EW 0.58 mm, EI 1.70; humeral calli weakly marked; basal impressions shallow but distinct; apices of elytra separately rounded. Punctures on elytra dense but small and shallow; setae dense, short, suberect.

Legs ( Figs 1, 3, 6 View FIGURES 1–6 , 7, 9–10, 12 View FIGURES 7–12 ) moderately long and slender; trochanters unmodified, femora clavate, profemur distinctly thicker than meso- and metafemur, with distinct ventral elongate tooth-like projection at base ( Figs 4 View FIGURES 1–6 , 12 View FIGURES 7–12 ); tibiae slender, protibia lacking apical denticle, mesotibia with short distal denticle and tuft of several thick, conspicuously long undulating setae in subapical region, metatibia unmodified; all tarsi long and slender.

Female. Unknown.

Distribution. Cenomanian of the present-day Myanmar.

Etymology. The name dentipes refers to the tooth-like projections on the profemora.

Remarks. Scydmobisetia dentipes differs from S. vetutissima in distinctly larger body (1.75 mm vs. 1.55 mm); different proportions of pronotum (PL/PW 1.18 vs. 1.54) and elytra (EI 1.70 vs. 2.15); and in less thickened an- tennae. Males identified by Yin et al. (2018) as S. vetutissima have mesotibiae with tufts of subapical setae, but lack profemoral projections. If the holotype of S. vetutissima is in fact a female, and not a male, as identified by Jałoszyński et al. (2016) (and then the species of Yin et al. (2018) is a new one), it differs from the male of S. den- tipes sufficiently to exclude a possibility that they are conspecific. The holotype of S. dentipes has stouter elytra and pronotum, but the same relative length of antennae as the holotype of S. vetutissima (AnL/BL for holotypes of S. vetutissima and S. dentipes equals 0.46–0.47). In extant Stenichnini, females are stouter than males (i.e., they have lower pronotal and especially elytral indexes), and their antennae are relatively shorter.

The males of S. loebli and S. mengjiae , in turn, are distinctly larger than that of S. dentipes (BL of S. loebli 2.11 mm vs. 1.75 in S. dentipes ; the holotype of S. mengjiae is incomplete, but has the length of head + pronotum 0.91 mm, vs. 0.78 mm in S. dentipes ), and have clearly different leg modifications, lacking the profemoral projections.

Since the description of Scydmobisetia , a pair of considerably long vertexal setae was found also in some extant Stenichnini ( Jałoszyński 2019). However, only in the extinct Scydmobisetia these setae are conspicuously long and thick, and still (in combination with other features) represent an important diagnostic character. The number of basal elytral foveae in this genus is still unclear; one poorly visible fovea was reported by Jałoszyński et al. (2016), and putatively one fovea by Yin et al. (2018). However, in S. dentipes there seem to be two poorly visible, small basal elytral foveae. It is also confirmed that the anterior metaventral process is well-developed in Scydmobisetia , and the mesoventral intercoxal process is missing.

NIGP

Naking Institute of Geology and Palaeontology

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