Adelothyreus brevis Otto, Muona and Córdoba-Alfaro, 2023

Otto, Robert L., Muona, Jyrki & Córdoba-Alfaro, Jim, 2023, A new genus and sixteen new species of false click beetles (Coleoptera: Eucnemidae) described from the Heredia Province of Costa Rica with several additional records from the Osa Peninsula and Panama, Insecta Mundi 2023 (991), pp. 1-36 : 7-8

Adelothyreus brevis Otto, Muona and Córdoba-Alfaro , new species

Figures 10–12

Diagnosis. The presence of a very short anterior lateral pronotal ridge will distinguish the new species from all known Adelothyreus species present in Costa Rica.

Type material. Male holotype: “ COSTA RICA: Heredia; Est.Bio. La Selva , 50–; 150 m 10°26′N 84°01′W; Proy. ALAS, INBio-OET” / “M/06/085; 02 Mayo 1993; Bosque primario” / “ HOLOTYPE:; Adelothyreus ; brevis ♂; Otto, Muona & Córdoba-Alfaro; Det. R. L. Otto; 2019” (red printed label). Holotype to be deposited in INBC.

Description. Male holotype: Length, 2.5 mm. Width, 0.50 mm. Body elongate; uniformly dark black; antennae dark brownish black; legs dark brown; head, pronotum and elytra clothed with short, recumbent yellowish setae ( Figure 10 ). Head: Surface densely punctate, somewhat dullish, subspherical; frons convex, without median fovea or carina; apical margin of frontoclypeal region rounded, more than 2.0 times wider than base; mandibles stout, bidentate, densely punctate. Antenna: Pectinate from flagellomeres III–VIII, attaining about 2/3 the length of the body; flagellomere I longer than II; flagellomere II strongly, asymmetrically serrate; flagellomeres III–IV longer than wide, sub-equal, each shorter than V; flagellomeres V–VIII each sub-equal, longer than wide; flagellomere IX longer than VIII; rami on flagellomeres III–VIII arising at apical end, short and about as long as the length of the segment. Pronotum: Surface somewhat dullish, closely punctate; longer than wide, with poorly developed hind angles; lateral sides parallel-sided, laterally sinuous above pronotal hind angle, apically arcuate; disc flattened without median groove; anterior lateral pronotal ridge extremely short, directed posteroventrally; posterior lateral pronotal ridge elongate, extending at least 3/4the length of pronotum ( Figure 11 ); base sinuous, with circular strong impressions above scutellar shield. Scutellar shield: Quadrate, sub-triangular, shallowly punctate, setose and distally rounded. Elytra: Striate indistinct; interstices flattened; surfaces shiny, closely punctate to rugose at basal 1/2, shallowly and closely punctate at apical 1/2. Legs: First tarsomere as long as the combined lengths of the remaining four on meso- and metatarsi; tibiae rounded in cross section; metatarsomeres I–III simple; metatarsomere IV very short, excavate; metatarsomere V short with simple claws. Venter ( Figure 12 ): Closely punctate, with short, recumbent yellowish setae; hypomeron with apically widened notosternal antennal grooves; antennal grooves smooth, scarcely punctate apically; metepisterna caudally wide; elytral epipleura punctate; metacoxal plates parallel-sided.

Distribution. This eucnemid species is known only from its type location in Costa Rica

Biology. The holotype was taken from a primary forest. Larvae and pupae are unknown.

Etymology. The specific epithet is derived from the presence of a very short anterior pronotal lateral ridge.

Figures

Figures 10–16. Costa Rican Adelothyreus species. 10) Adelothyreus brevis sp. nov., dorsal habitus. 11) Adelothyreus brevis sp. nov., pronotal lateral habitus. 12) Adelothyreus brevis sp. nov., ventral habitus. 13) Adelothyreus costaricensis sp. nov., male holotype, dorsal habitus. 14) Adelothyreus costaricensis sp. nov., male holotype, pronotal lateral habitus. 15) Adelothyreus costaricensis sp. nov., male holotype, ventral habitus. 16) Adelothyreus costaricensis sp. nov. female allotype, dorsal habitus. (Scale: 10–16 = 1.0 mm)