Oocyclus radiatus, Short & Torres-Gavosto & Hettinger, 2023

Short, Andrew E. Z., Torres-Gavosto, Juan Martin & Hettinger, Ty, 2023, A review of the Oocyclus Sharp of Ecuador with description of 12 new species (Coleoptera: Hydrophilidae: Laccobiini), Zootaxa 5277 (1), pp. 91-112 : 101-102

Oocyclus radiatus sp. n.

( Figs. 3A , 6B , 7 )

Type Material. Holotype (male): “ECUADOR, Pich.,/ Sto. Domingo de/ los Colorados, / 44KmE., 10 July 1975 / Jeffrey Cohen”, “ ECUADOR-PEACE CORPS,/ SMITHSONIAN INSTITUTION/ AQUATIC INSECT SURVEY” ( USNM) . Paratypes (77 exs.): ECUADOR: Manabí Province: 79 km W. Santo Domingo de los Colorados , 8.v.1975, leg. P. Spangler, A. Langley, & J. Cohen, seepage over rock outcrops in roadcuts (20 exs., USNM, SEMC) ; 26.5 km E. Flavio Alfaro , 380 m, 8.i.1978, leg. P. Spangler, roadside seep (3 exs., USNM) ; 38 km E. Portoviejo , 11.v.1975, leg. P. Spangler, A. Langley, & J. Cohen, splash zone at waterfall, (35 exs., USNM, SEMC) . Pichincha Province: 14 km E. Santo Domingo de los Colorados , 5.vii.1975, leg. A. Langley & J. Cohen (11 exs., USNM) ; 25 km E. Santo Domingo de los Colorados , 5.vii.1975, leg. A. Langley & J. Cohen (8 exs., USNM) ; same data as holotype (9 exs., USNM, SEMC) . Sucumbíos Province: 146 km W. Lago Agrio, 18.v.1975, leg. P. Spangler, A. Langley, & J. Cohen, roadside ditch (1 ex., USNM) .

Diagnosis. Larger species. Posterolateral corners of pronotum angulate, but not spinose. Prosternal carinae set with two spines anteriorly. Elytra with first row of systematic punctures forming a dense, broken row bearing erect setae. Elytral margins slightly explanate, without a fringe of long setae. Abdominal ventrites bicolored, with dark anterior margins and pale posterior margins.

Of larger-bodied species in Ecuador, O. radiatus is most similar to O. pakcha , which also has angulate posterolateral pronotal corners, however it can easily be distinguished by the broken irregular first row of erect setae on the elytra while O. pakcha has a dense continuous row. It is also similar to O. ustulatus , but that species has spinose posterolateral angles of the pronotum and a pale yellow abdominal venter.

Description. Size and Form. Length = 4.3–5.4 mm.Very broadly oval, slightly convex.( Fig. 3A ). Color. Dorsum of head, pronotum, and elytra black, with faint iridescent green reflections. Anterolateral margins of pronotum with large, broad pale spot, extending nearly half the length of the margin. Elytra with very faint iridescent green maculae which often appear faint and with defuse borders. Maxillary and labial palps yellow. Mentum and stipes dark brown, similar in color to the venter of the head. Thoracic ventrites and legs are reddish to dark brown. Abdominal ventrites with a distinct banding pattern, with the anterior half of each ventrite reddish to dark brown and the posterior margin distinctly paler, being light brown to orange, with the thickness of the posterior orange band widening laterally.

Head. Ground punctation on labrum, clypeus and frons fine, distance between punctures 2.0–3.0× the width of one puncture. Systematic punctures on labrum consisting of several indistinct punctures, sometimes bearing a short seta. Frons with an irregular row of systematic punctures bearing setae mesad of each eye. Clypeus with a few very indistinct systematic punctures along anterolateral margins, slightly larger than surrounding punctation. Maxillary palps short, about as long as width of mentum; segment 2 slightly bulbous, apical segment approximately the same length as penultimate. Labial palps less than half as long as width of mentum; with clump of long setae on second segment. Mentum quadrate with fine scattered punctures, anterior margin slightly convex and depressed. Thorax. Ground punctation on pronotum and elytra composed of very fine, evenly distributed punctures. Pronotal systematic punctures with short fine setae, at least 2× the size of surrounding ground punctures, anterior and posterior series each forming an irregular field. Lateral margins of pronotum set with a few sparsely distributed setiferous punctures; with punctures almost appearing absent. Posterolateral corners of pronotum angulate, but not spinose. Elytral margins slightly explante posteriorly. Sutural punctation on elytra absent or unmodified from ground punctation; sutural interval not raised in posterior half. Elytra with five rows of systematic punctures: the first row is represented as a grove with a moderately dense, nearly continuous row of erect setae. Rows 2 and 3 represented by a nearly regular series of coarse punctures bearing slightly shorter and more sparsely set setae than row 1. Punctures in rows 4 and 5 similar to 2 and 3 but irregular in distribution. Prosternum with a clearly defined median carina; slightly elevated anteromedially, the elevation set with two spines. Elevated process of the mesoventrite narrow and elongate, more than three times as long as wide; surface nearly flat; set with 6–7 thickened, coarse spines. Metaventrite with oval glabrous area posteromedially, slightly less than twice as long as wide, length of glabrous area slightly more than half the length of metaventrite. Procoxae covered with dense pubescence that is interspersed with short, thickened spines. Protibiae with 12 spines on dorsal face. Abdomen. Ventrites covered with fine setae, the longest setae not longer than the longest setae surrounding the glabrous area of the metaventrite. Aedeagus as in Figure 6B .

Distribution. Known from a series of localities in the north of Ecuador, most on the western slopes of the Andes but also one locality on the eastern slope ( Fig. 7 ).

Etymology. Named after the “sunrise” like coloration of the abdominal ventrites, which are half dark and half orange.

Figures

FIGURE 3. Dorsal, ventral and lateral habitus views of Oocyclus species. (A) radiatus sp. n. (B) ustulatus sp. n.

FIGURE 6. Aedeagi of Oocyclus species in Ecuador with angulate or spinose posterolateral corners of the pronotum. (A) ustulatus sp. n. (B) radiatus sp. n. (C) pakcha sp. n. (D) sumak sp. n. (E) ankas sp. n. (F) lepidus sp. n. (G) bellus sp. n. (H) zamora sp. n. (I) specimen of the morgani/trujillo species group (J) specimen of the morgani/trujillo species group.

FIGURE 7. Distribution of Oocyclus spp. in Ecuador.