Prototyrtaeus gracilicornis Spiessberger and Ivie, new species

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(Figs. 6, 15f, 16k, 17e)

Type Material. Holotype. PUERTO RICO:; Caribbean Nat. For.; Pico El Yunque, 1005m; 23SEP1987, M.A. Ivie; litter und. Treefern (WIBF, to be deposited in the NMNH) . Paratypes (19). 5: Same locality data as holotype (3 WIBF, 1 CMNH, 1 CNCI). 6: El Yunque; c. 3,000 ft, P.R.; May 1938; Darlington (5 MCZC, 1 WIBF). 2: PUERTO RICO; El Yunque Peak; III-28-1970 litter; R. Lavigne (WIBF). 1: West Peak; Puerto Rico (MCZC). 1: Luquillo Forest; East Peak, P.R.; July. 15, 1969; H. & A. Howden (CNCI). 1: PUERTO RICO:; El Verde Research Sta; ridge tops in forest; 02-30 SEP 1996; E. Nazario, pitfall (WIBF). 3: PUERTO RICO: Liquillo [sic]; Forest, Big Tree trail; 05 DEC 1959, G.F. Haas; ex forest debris (2 INHS, 1 WIBF) .

Diagnosis. This species can be distinguished by having a non-metallic integument, a unicolored antenna with antennomere 3 distinctly longer than 2 (Fig. 15f), and the head with confluent punctures forming strigulae (more evident under LED white light). It is the only species with acute anterior angles on the pronotum, the anterior margin of the pronotum beaded, the pronotum widest at base, and the intercoxal process of ventrite 1 rounded (Fig. 16k).

Etymology. The species name is a Latin adjective that refers to the thin and slightly elongate antennae of this species.

Description. 2.0– 2.5 mm long, 1.2–1.5 mm wide. Dorsal surface brown without distinct setation, only a few microsetae and a few longer setae along lateral elytral margin, shiny when less sclerotized; antenna brown. Head not as wide as anterior edge of pronotum, frons moderately coarsely punctate, punctures confluent, forming strigulae (more evident under LED white light), glabrous; epistomal suture moderately marked; clypeus setose with higher concentration of setae at apex; labrum with longer, denser setae; antenna with 9 antennomeres (Fig. 15f), antennomere 3 distinctly longer than 2, antennomere 6 distinctly thinner, shorter than 7, antennomeres 7–9 forming club, gradually decreasing in width, antennomere 7 widest, club shorter than antennomeres 1–6, last antennomere rounded at apex. Pronotum strongly transverse, widest at base, sparsely, finely punctate, punctures smaller than eye facet; all margins beaded, anterior margin bisinuate, lateral margin nearly straight, strongly beaded, bead width gradually increasing posteriorly, visible setae in dorsal view projecting laterally, posterior margin arcuate with bead nearly effaced medially, anterior angles acute, with bead of lateral margin weakly projecting forward, posterior angles obtuse. Elytron without striae, with faint, shallow, small punctures, 1 long seta behind basal margin, pair of long setae above lateral groove on basal fourth, 1 long seta above lateral groove on apical third (if missing, distinct puncture present) (Fig. 16a). Metaventrite short, lateral area smooth; metanepisternum smooth. Pro- and mesocoxae rounded (external view), metacoxa transverse, narrowing outwards, femora with short, sparse, golden setae, protibia cylindrical, with sparse, straight, golden setae on dorsal surface, ventrally completely setose, becoming dense, golden brush on apical half, tarsomere 1 slightly enlarged (Fig. 16e). Intercoxal process of ventrite 1 rounded (Fig. 16k), sparsely punctate, punctures each bearing a very fine, golden seta. Aedeagus (Fig. 17e) with basale twice longer than apicale; in lateral view, basal 2/3 of basale curved, apical fourth of apicale curved.

Distribution. Puerto Rico (Fig. 20).

Biology. The label data on this series indicate this species lives in litter on the ground, where it was taken under a tree fern.

Remarks. This species has been found only in the Luquillo Mountains of eastern Puerto Rico. Like another Puerto Rican species of apparently limited distribution, P. pecki, this species seems to live in litter on the ground.