Latridius usovae Sergi et Perkovsky, 2014

Sergi, T. A. & Perkovsky, E. E., 2014, Latridius Usovae, A New Species Of The Minute Brown Scavenger Beetles (Coleoptera, Latridiidae) From Rovno Amber, Vestnik Zoologii 48 (4), pp. 319-324 : 320-323

Latridius usovae Sergi et Perkovsky , sp. n. ( fig. 1 , 2 )

M a t e r i a l. Holotype, SIZK UA–51 , sex unknown; Rovno amber, Late Eocene. The specimen in a small triangular amber piece (length about 11 mm and width 7 mm).

Most part of the head, right half of pronotum, right antenna and segments 1–4 of the left antenna, right fore and mid tibiae missing. Sculpture of the transversal impression on pronotum (from fovea to fovea) and sculpture of the fore third and lateral parts of the first visible sternite not visible.

D e s c r i p t i o n. Length about 1.0 mm, width 0.53 mm. Dorsal surface unicolorous brownish, glabrous. Elongate, moderately convex ventrally and with strongly convex elytra. Integument with slight shine.

Head about 0.3 mm wide, with distinct punctures larger than eye facets in diameter; temple rounded, about 0.5 of eye length; vertex evenly convex. Neck not visible. Eye large, longitudinal diameter 0.07 mm, strongly convex, with distinct facets (diameter of eye about 10 facets).

Antenna moderately slender. Three remaining flagellomeres subequal in length and about as long as broad; penultimate flagellomere short and transverse; two remaining segments of club thick and forming loose club twice as wide as other flagellomeres.

Pronotum transverse, 0.25 mm long, 0.32 mm wide; widest in anterior third, narrowed posteriad; anterior margin convex, lateral margins in anterior 1/2 convex and rounded, in posterior third subparallel, posterior margin straight; anterior angles widely rounded, posterior angles narrowly rounded; lateral sides explanate. Pronotum covered with dense coarse punctures, larger than eye facets in diameter, interspaces much smaller than puncture diameter; basal and lateral sides bordered. Disc evenly convex and gradually sloping to sides. Pronotum with transverse impression at base (obscured by milky film); two deep oval depressions near posterior angles; shallow median longitudinal depression. Scutellum small, transverse, 0.03 mm wide.

Elytra 0.7 mm long, about 1.3 times as long as wide, widest before the middle; moderately convex at disc and rather steeply sloping at sides, lateral sides narrowly explanate. Humeri distinct. Punctures in elytral rows very large and deep, about two to three times as large as pronotal punctures, becoming slightly smaller on elytral apex; interspaces about half puncture diameter. Punctures forming 8 regular rows, with interstriae narrow, about 0.5 puncture diameter; interstriae 1, 3, 5 and 7 slightly carinate; interstriae 3 and 7 closed posteriad. Interstria 1 not widened; first punctured row with about 26 punctures. Elytra very narrowly rounded at apex. Epipleurae of elytra wider in anterior part and gradually narrowing posteriorly, in anterior half with row of large punctures.

Fully winged; distal half of right wing and apex of left wing visible; hind margin with hairs 0.02 mm long.

Procoxa projecting, prosternum low, without elevated ridge between procoxae.

Metasternum with pit just behind mesocoxa (obscured by milky film), with radial lines long, reaching posterior third of metasternum; with shallow longitudinal furrow in posterior half. Meso- and metasternum, except pits with radial lines, closely and coarsely punctate (approximately as on pronotum). Abdomen with five visible ventrites, lateral parts of them obscured by milky film. First abdominal ventrite longest (as long as ventrites 2–4 combined), covered with dense punctures, slightly finer than on metasternum, ventrite 2 with fine sparse punctures, ventrites 3–5 nearly smooth.

Рис. 1. Latridius usovae sp. n.: 1 — вид сверху; 2 — вид снизу; 3 — антенна; 4 — средняя нога; 5 — задняя нога.

Рис. 2. Latridius usovae sp. n.: 1 — вид сверху; 2 — передняя нога; 3 — средняя нога; 4 — задняя нога.

Legs moderately long and narrow. Trochanters obliquely truncate, about as long as broad. Femora spindle-shaped, thickened distally and 2.0–2.5 times as wide as tibiae; fore femur with longitudinal wrinkles on ventral surface. Tibiae thin, as long as femora; fore tibia feebly curved, 0.2 mm long; mid tibia straight, 0.2 mm long, with big straight apical tooth as long as tarsomere 1; hind tibia slender, distinctly curved inwards, 0.22 mm long. Fore and mid tarsi about 2/3 as long as respective tibiae, hind tarsus about 2/5 as long as hind tibia; tarsomeres 1 and 2 equal in length; tarsomere 3 distinctly longer than both previous ones together. Claws simple, small and thin.

E t y m o l o g y. The species named in honour of Professor Zinaida Usova (1924–2013), scientific adviser of the first author.

Comparison. The new species differs from L. jantaricus by the anterior angles of pronotum not projecting forward, lack of depressions at anterior angles of pronotum, shallow median longitudinal depression ( L. jantaricus has anterior angles of pronotum moderately projecting forward, disc of pronotum with depression near middle of lateral margin and with deep median longitudinal depression); shorter elytra, lack of strong carinae on interstriae of elytra. L. usovae differs from L. alexeevi by having anterior angles of pronotum not projecting forward, lacking depressions at anterior angles of pronotum (in L. alexeevi anterior angles of pronotum moderately projecting anteriorly, disc of pronotum with shallow depressions at anterior angles), and in having elytra about 1.3 times as long as wide (vs. about 1.5 times in L. alexeevi ). The new species differs from both species by having hind tibia distinctly curved mesally.

The new species is similar to the extant species L. crenatus (Le Conte, 1855) from the western Canada and USA ( Fall, 1899; Hatch, 1962) in the shape of pronotum and puncturation of elytra, but clearly differs in having meso- and metasternum closely and coarsely punctured, ventrite 1 densely punctured and in the shape of tibiae.

Figures

Fig. 1. Latridius usovae sp. n.: 1 — body, dorsal; 2 — body, ventral; 3 — antenna; 4 — middle leg; 5 — hind leg.

Fig. 2. Latridius usovae sp. n.: 1 — body, dorsal; 2 — fore leg; 3 — middle leg; 4 — hind leg.