Phasmister hkamticus Caterino and Yamamoto, 2023

Caterino, Michael S. & Yamamoto, Shûhei, 2023, New Onthophiline Fossil Species (Coleoptera: Histeridae: Onthophilinae) from Mid-Cretaceous Burmese Amber, The Coleopterists Bulletin 77 (3), pp. 432-438 : 433-435

Phasmister hkamticus Caterino and Yamamoto , new species zoobank.org/ urn:lsid:zoobank.org:act:C32C48F8-68A5-4313-A6E1-DE609FF0ADE1 ( Figs. 1 , 3B )

Type Material. Holotype specimen, of unknown sex (SEHU-0000121202); deposited in HUM. Type locality: Northern Myanmar: Sagaing Region, Hkamti District . The holotype is embedded in a small, elongate-oval, yellowish transparent amber piece (9.8 × 4.9 × 1.7 mm).

434 Diagnostic Description. Full body length, in situ: with posterior and lateral margins raised, antennal 1.21 mm (apex of head to posterior end of abdomen); insertions open anteriorly; antennal club with disbody (pronotum + elytra) length along midline: tinct transverse annuli; prosternum with lateral slots 1.02 mm; maximum (humeral) width: 0.71 mm; for passage of the antennal funicle; hypomeral head width: 0.26 mm; pronotal length: 0.34 mm; antennal depression open beneath. Phasmister pronotal width: 0.56 mm. This species shares many hkamticus differs from P. cristatus in the following of the generic level characters described for specific characters: prothorax less strongly trans- Phasmister (Caterino 2021) : body subquadrate, verse, length/width ratio slightly greater (see Fig. 3 ); weakly compressed; elytra with every second inter- anterior corners of pronotum not as produced, less stria strongly raised to form a carina; humeral elytral deeply explanate; anterior margin of pronotum angles expanded; pronotum with raised lateral and rather narrow; median pronotal carina less dorsally anterior margins, depressed in anterior corners, with projecting (as seen in lateral view), little higher than various carinae on disc; pronotal disc strongly car- elytral carinae, more obtusely divergent near apex, inate; posterior pronotal margin sinuate, produced then angulate to anterior margin, enclosing a disposteriad in front of small scutellar shield; frons tinctly (irregularly) pentagonal space; sublateral elongate; propygidium deeply concave in basal half, punctate apically; pygidium with apex directed nearly anteriad.

Derivation of Specific Name. The name hkamticus is an adjective referring to the novel source of amber (the Hkamti amber deposits) in which the specimen was found.

Remarks. The differences between this species and P. cristatus are well-marked, despite their clearly close relationship. The distinct conformation of pronotal carinae separates them most clearly, with the broader, pentagonal area between the median carinae ( Fig. 3B ) of the new species quite distinct. The apparently lower overall elevation of the median pronotal carina also appears distinctive. The differences of both of these species from Phasmister parallelus , new species are more noteworthy. Most distinct are the differences in tibial shape, particularly in the broad, outwardly angulate protibia of P. parallelus , with a medial rather than marginal groove. Phasmister hkamticus and P. cristatus are both distinctly flattened dorsally, where the species described below is more convex.

Syninclusions. No arthropod inclusions are included, but there is some small organic debris and a partial remnant of a boring of Pholadidae ( Bivalvia: Myoida) within the amber piece.

Figures

Fig. 1. Habitus images of Phasmister hkamticus, new species. A) Dorsal, B) Dorsolateral, C) Lateral, D) Ventral, E) Anterodorsal, F) Posterodorsal. All scale bars 0.5 mm.

Fig. 3. Comparison of pronota of Phasmister spp. A) P. cristatus, B) P. hkamticus, new species, C) P. parallellus, new species.