Leptorhyparus quadricornis Skelley, 2021

Skelley, Paul E., 2021, A new species of Leptorhyparus Howden, 2003 (Coleoptera: Scarabaeidae: Aphodiinae: Rhyparini) in amber from the Dominican Republic, with comments on extant species, Insecta Mundi 2021 (892), pp. 1-7 : 5

Leptorhyparus quadricornis Skelley , new species

Figures 9–17

Diagnosis. Leptorhyparus quadricornis is readily distinguished from all other Rhyparini by the small size and head with four distinct pencil-like tufts of setae. It is a fossil in amber from the Dominican Republic.

Description. Holotype length 2.1 mm. Body apparently dark brown or entirely black; shape elongate, parallel-sided ( Fig. 12 ). Head. Head with distinct punctures ( Fig. 9 ). Clypeus with angulate tooth on each side of slightly concave median third of margin ( Fig. 16 ); edge with narrow elevated bead; centroclypeal disc with 2 low costae. Frons with 4 weak costae, each with a pencil-like tuft of setae. Pronotum. Pronotum rectangular; costae low, broad, convex ( Fig. 13, 15 ), weak near anterior margin, almost reaching posterior margin; lateral margin strongly sinuate, anterior and intermediate lobes small. Elytron. Elytron almost twice as long as head and pronotum combined; sides almost parallel for 4⁄5 of length; all costae low, broad, convex ( Fig. 13, 15 ); discomedian costa with distinct pencil-like erect setal tuft at caudal apex; caudal bulb divided into inner and outer lobes ( Fig. 13–15 ). Venter. Metaventrite appears flattened either side of midline. Abdomen. Abdomen with length of apical ventrite equal to preceding three combined; all ventrites smooth. Legs. Meso- and metafemur elongate-oval, not clavate ( Fig. 17 ). Meso- and metatibia gradually triangularly widening to truncate apex, slightly flattened. Metatibia with small but distinct spine on inner margin. Meso- and metatarsi elongate, first tarsomere as long as next 3 combined, claws minute.

Material examined. Holotype ( FSCA; Fig. 9 , 12–17 ) is in dark opaque amber with many cracks and irregularities. A paratype ( CEMT; Fig. 10–11 ) is in transparent amber, but details are not readily visible due to cracks and irregularities in the amber. Wu (1996) did not state where the specimen imaged in the book was deposited, it was not available for study. The image in Wu (1996: 187, fig. F-459) was consulted.

Etymology. The species epithet is a masculine adjective in the nominative singular meaning four-horned.

Comments. The available specimens are poorly visible in the amber, with only some structures visible. Enough are visible to identify them as this species. In all cases, visible setal tufts on the head are unlike any known species of Rhyparini . Placement in Leptorhyparus is based on the small body size, elytral tuft of setae on apex of discomedian costa, smoothly elongate body shape, small pronotal anterior lateral lobes, low costae, and apparently divided caudal bulb of elytra. The holotype is in a small piece of dark amber that has many cracks and layers preventing easy visibility. However, there were a couple narrow ‘windows’ of clarity that allowed some photography. With digital enhancement, the images presented here allowed for the description above. A better specimen or use of high-tech Micro CT imaging systems may allow a better description to be made someday. Naming it now documents the species for future studies.

Figures

Figures 9–11. Leptorhyparus quadricornis. 9) Head of holotype. 10–11) Lateral and dorsal view of L. quadricornis, paratype CEMT, line = 1.0 mm. Photos in Figures 10–11 by Vinícius Costa-Silva (CEMT).

Figures 12–17. Leptorhyparus quadricornis, holotype. 12) Dorsal view. 13) Oblique dorso-posterior view, arrows point to setal tuft on apex of dorsomedian costa and bilobed caudal bulb. 14) Oblique dorso-anterior view. 15) Oblique dorso-posterior view. 16) Head, anterior view. 17) Ventral view.