Oocyclus pakcha, 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 : 99-100

Oocyclus pakcha sp. n.

( Figs. 6C , 7 )

Type Material: Holotype (Male): ECUADOR, Tung./ Banos (18kms.E)/ 25Jan.1976, 5130′/ Spangler et al. ”, “Seepage over/rock outcrops/ in roadcuts”, “ECUADOR-PEACE CORPS./SMITHSONIAN INSTITUTION/ AQUATIC INSECT SURVEY” ( USNM) . Paratypes 295 exs.): ECUADOR: Cotopaxi Province: 79 km E Quevedo , 1225′, 12.v.1975, leg. P. Spangler, A. Langley, & J. Cohen, small waterfall (7 exs., USNM); 117 km W Latacunga , 3000′, 1.vii.1975, leg. A. Langley & J. Cohen (9 exs., USNM) . Loja Province: 18 km N Loja , 1900m, 28.xi.1978, leg. J. Anderson (36 exs., USNM) . Napo Province: 72 km E. Baeza , 4200′, 16.v.1975, leg. P. Spangler, A. Langley, & J. Cohen, seep at waterfall (4 exs., USNM) ; 5 km SE Baeza , 1900m, 9.ix.1990, leg. P. Spangler, stream (1 ex., USNM) ; Just above San Rafael Falls , 1510m, 21.viii.1979, leg. J. Anderson, cascade-seep (3 exs., USNM) . El Oro Province: Salvias , 1400m, 9.vi.1979, leg. J. Anderson (72 exs., USNM) . Pastaza Province: 31 km W Puyo , 9.v.1977, leg. P. Spangler & D. Givens, roadside ditches (10 exs., USNM) . Tungurahua Province: 39 km E Baños , 28.i.1976, leg. P. Spangler et al., roadside seep (59 exs., USNM) ; same data as holotype (79 exs., USNM) ; 20 km E Baños , 28.i.1976, leg. P. Spangler et al., seepage over rock outcrops in roadcuts (1 ex., USNM) ; 9 km E Rio Negro , 9.v.1977, leg. P. Spangler & D. Givens (13 exs., USNM) ; 6 km E Rio Negro , 20.v.1977, leg. W. Steiner (1 ex., USNM) . Zamora-Chinchipe Province: 30 km SE Loja , 2000m, 23.ix.1990, leg. P. Spangler, spring seepage (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 variable in color from uniformly dark brown to partly pale colored.

Of larger-bodied species in Ecuador, O. pakcha is most similar to O. radiatus , which also has angulate posterolateral pronotal corners, however it can easily be distinguished by the dense continuous row of erect setae on the elytra while O. radiatus has a broken, irregular 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 = 4.7–5.0 mm. Body oval, slightly convex. Color. Dorsum of head, pronotum, and elytra black, with faint iridescent green reflections. Anterolateral margins of pronotum with pale patch extending about one-third to one-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 dark brown. Legs dark to medium brown. Abdominal ventrites variable in color, completely dark in some specimens, while appearing bicolored or at least party pale laterally in others. Head. Ground punctation on labrum, clypeus and frons moderately fine, distance between punctures 1.0–2.0× 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 labrum; 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 and slightly rugose, anterior margin slightly convex and depressed. Thorax. Ground punctation on pronotum and elytra composed of fine, evenly distributed punctures. Pronotal systematic punctures with short fine setae, at least 2x 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; but without a dense fringe. Posterolateral corners of pronotum angulate, but not spinose. Sutural punctation on elytra absent or unmodified from ground punctation; sutural interval raised in posterior half. Elytra with five irregular rows of systematic punctures: the first row is represented by dense, continuous coarse punctures bearing erect setae, giving a “mohawk” like appearance. Rows 2–5 are represented by irregular series of larger coarse punctures usually bearing a small recumbent setae. 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 coarse spines. Metaventrite with oval glabrous area posteromedially, ca. twice as long as wide, length of glabrous area slightly more than length of metaventrite. Procoxae covered with dense pubescence and set with a few scattered, short spine-like setae. Protibiae with 10–12 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 6C .

Etymology. Pakcha is the Kichwa word for waterfall. Named in reference to the habitat of this species.

Distribution. Known from a broad range of localities on both sides of the Andes ( Fig. 7 ).

Remarks. This species exhibits more variation than most other species in the region. In particular, the coloration of the venter varies from nearly entirely dark brown in some specimens to distinctively two-toned in others, with the legs and portions of the abdominal ventrites paler than the thoracic venter. The size of the anterolateral pale spot on the pronotum is also variable in size from small and faint to quite large and distinct. However, there was wide variation in these color forms rather than two distinct groupings, and we did not observe any other consistent differences that covaried with coloration. For those reasons, we prefer to describe these specimens as a single species. However, it would not surprise us if future studies with additional data determined that O. pakcha is actually a species complex.

Figures

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.