Adelothyreus costaricensis 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 : 8-9

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

Figures 13–16

Diagnosis. This new species is very similar to A. comes . The posteroventrally directed anterior lateral pronotal ridge will distinguish the new species from A. comes .

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/01/332; 01 Febrero 1994; Parcelas sucesionales” / “ HOLOTYPE:; Adelothyreus ; costaricensis ♂; Otto, Muona & Córdoba-Alfaro; Det. R. L. Otto; 2019” (red printed label). Female allotype: “ COSTA RICA, Heredia; Est.Bio. La Selva , 50–; 150 m, 10°26′N 84°01′W; Proy. ALAS, INBio-OET” / “M/15/121; 02 Junio 1993; Bosque secundario” / “ ALLOTYPE:; Adelothyreus ; costaricensis ♀; Otto, Muona & Córdoba-Alfaro; Det. R. L. Otto; 2019” (yellow printed label). Holotype and allotype are to be deposited in INBC .

Description. Male holotype: Length, 2.5 mm. Width, 0.75 mm. Body elongate; uniformly dark black; antennae dark brownish black; femur and tibiae dark brownish black; tarsi dark brown; head, pronotum and elytra clothed with short, recumbent yellowish setae ( Figure 13 ). 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 II–VIII, attaining about 2/3 the length of the body; flagellomere I longer than II; flagellomeres II–III sub-equal, each shorter than IV; flagellomere IV longer than III, shorter than V; flagellomeres V–VIII each sub-equal, longer than wide; flagellomere IX longer than VIII; ramus on flagellomere II arising along entire length, rami on flagellomeres III–VIII arising at apical end, elongate and about 1.5 times longer than length of segment. Pronotum: Surface somewhat dullish, closely punctate; longer than wide, with poorly developed hind angles; lateral sides parallel-sided, apically arcuate; disc convex without median groove; anterior lateral pronotal ridge short, arcuate, directed posteroventrally; posterior lateral pronotal ridge elongate, about 3/4 the length of the pronotum ( Figure 14 ); base sinuous, with circular strong impressions above scutellar shield. Scutellar shield: Short, quadrate, sub-triangular, shallowly punctate, setose and distally rounded. Elytra: Very shallow striate indicated; interstices slightly elevated; surfaces shiny, very closely punctate to rugose at basal 1/2, 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 15 ): Closely punctate, with short, recumbent yellowish setae; hypomeron with apically widened notosternal antennal grooves; antennal grooves smooth, sparsely punctate; metepisterna caudally wide; elytral epipleura punctate; metacoxal plates parallel-sided.

Female allotype ( Figure 16 ): Length, 3.0 mm. Width, 1.0 mm. Antennae serriform, about 1/2 the length of the body; flagellomere I longer than wide, longer than II; flagellomere II quadrate, serrate, shorter than III; flagellomeres III–VIII sub-equal, transverse, asymmetrically serrate; flagellomere IX longer than VIII.

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

Biology. The holotype was taken from a successional plot of trees. The allotype was taken from a secondary growth forest. Larvae and pupae are unknown.

Etymology. The specific epithet is named for the country of Costa Rica from which the new species was taken.

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)