Tytthonyx (Tytthonyx) milleri, 2022

Ivie, Michael A., Fanti, Fabrizio & Ferreira, Vinicius S., 2022, A New Tytthonyx LeConte (Coleoptera: Cantharidae) from Dominican Amber, with Notes on Diagnostic Characters of West Indian Cantharids with Short Elytra, The Coleopterists Bulletin 76 (4), pp. 577-583 : 578

TYttHONYX (Tytthonyx) milleri Ivie, Fanti, and Ferreira , new species zoobank.org/ urn:lsid:zoobank.org:act:3175554E-150F-4ECF-9312-B46A65796F73 Fig. 1

Type Specimen. Holotype: female, in Dominican amber, accession no. WIBF 049821 .

Type Locality. Dominican Republic: Cordillera Septentrional .

Type Horizon. Late Early/Middle Miocene; 15–20 million years ago (mya), probably close to 16 mya. La Toca Formation.

Etymology. The species is named after the late Richard Stuart Miller (1945–2021). Rich’s interests were mainly focused on “cantharoids”, most strongly on Lycidae and Lampyridae , and his extensive collection was donated to the Montana Entomology Collection at Montana State University.

Diagnosis. The generic placement of the species is discussed below. Currently, four other species of short-elytra cantharids are known from Dominican amber, two of which have been described: T. geiseri and T. stadili . Tytthonyx milleri can be separated from T. stadili by its smaller size (2.8 mm in T. milleri and 6.0 mm in T. stadili ) and the flavous color ( T. stadili has a black face, elytra, venter, and basal eight antennomeres). Tytthonyx milleri has somewhat stronger serration of antennomeres 3–5 and a convex head (almost flat in T. stadili although this character state is possibly an artifact of preservation) (Fanti and Damgaard 2019). From T. geiseri , which is similar in size, it is quite different (see Discussion below). The easiest way to distinguish them is by the length of the antenna, which is as long as the body in T. milleri and longer than the body in T. geiseri . The form of the pronotum is also distinctly different, being more rounded anterolaterally (square in T. geiseri ) (Poinar and Fanti 2016). These characters are all potentially somewhat relat- ed to the different sexes of the types, but exceed the variation seen in most modern species.

Description. Female (based on the wide last abdominal ventrite), adult, alate, entirely flavous. Body length ca. 2.8 mm. Head completely exposed, elongate, narrowed behind the eyes, convex medially, pubescent and shallowly punctate. Eyes round, inserted laterally. Frontoclypeal region (face) constricted by antennal insertions near front of eyes, with a transverse depression between antennal insertions and a widened frontal margin, frontal margin nearly straight, slightly concave. Mandibles long, broad basal to the median strong retinaculum, thereafter long, thin, falciform. Maxillary palp 4-segmented; first palpomere robust, short; second elongate, cylindrical; third robust, intermediate in length between first two; fourth globular, apically pointed. Labial palp 3-segmented; terminal palpomere globular and apically pointed.Antenna with 11 antennomeres, serrate; relatively short, reaching ca. midpoint of abdomen; scape stout, club-shaped; antennomere 2 filiform, about two-thirds length of first; antennomeres 3–8 (especially 4–7) serrate, subequal in length; antennomere 9 slightly serrate; antennomeres 10–11 filiform with terminal antennomere rounded at apex; all antennomeres pubescent. Pronotum transverse, surface slightly convex, pubescent, shallowly punctate, slightly wider than head, corners round, anterior and posterior margins and lateral beads strongly bordered, sides irregular and slightly enlarged near the anterior margin, lacking secretory pore. Elytra very short, reaching base of first ventrite; slightly dehiscent apically, apices round; setae short. Hind wings fully developed, surpassing last abdominal tergite; costal margin with series of dark bristles; radial cell open; r-m connected at both ends; Mr apparently narrowly erased at base; M 3+4 complete; cubital vein not visible. Ventrites transverse, pubescent, last ventrite wide. Legs long, slender; pro- and mesocoxae conical; trochanters elongate and offset, rounded apically; femora and tibiae cylindrical, straight; with small, fine apical spur on pro- and metatibiae, slightly stouter on mesotibia. Tarsal formula 5-5-5; metatarsus with first tarsomere elongate and thin, the second tarsomere about one-third length of first, third tarsomere small, fourth very short and strongly bilobed, fifth tarsomere slender, subequal to second; claws simple and minute. Male unknown.

Figures

Fig. 1. Tytthonyx (Tytthonyx) milleri, new species in Dominican amber. Holotype (WIBF 049821). A) Right lateral view, scale bar = 1.0 mm, B) Left lateral view, scale bar = 1.0 mm.