Tobochares pallidus, Kohlenberg, Alex T. & Short, Andrew Edward Z., 2017

Kohlenberg, Alex T. & Short, Andrew Edward Z., 2017, Revision of the Neotropical water scavenger beetle genus Tobochares Short & Garcia, 2007 (Coleoptera, Hydrophilidae, Acidocerinae), ZooKeys 669, pp. 113-146 : 125-128

Tobochares pallidus sp. n. Figs 3B, 6 A–B, 7C, 9C, 10C, 11D, 12C, 14F, 15, 18 A–B, D–F

Type material.

Holotype (male): "VENEZULEA: Amazonas State/ 5°23.207'N, 67°36.922'W, 125m/ Tobogan de la Selva; 8.viii.2008/ leg. A. Short, M. García, L. Joly/ AS-08-080b; old “tobogancito” / on seepage area w/ detritus", "[barcode]/ SEMC0877702/ KUNHM-ENT" (MIZA). Paratypes (28): VENEZUELA: Amazonas: same data as type (10 exs., SEMC, MALUZ, MIZA); same locality but leg. M. Balke (1 ex., SEMC; DNA voucher SLE525); same locality but 23.ii.1986, leg. Spangler, sandy margin, Colln. #10 (1 ex., USNM); same locality but 18.i.1989, leg. Spangler, Faitoute, & Barr, upper seep (1 ex., USNM); nr. Hotel Nacamtur, 5°36'16.18"N, 67°34'56.24"W, 14.ix.2007, isolated rock seep w/ algae, leg. A. Short, AS-07-013x (1 ex., SEMC). Bolivar: Los Pijiguaos, 6°35.617'N, 66°49.238'W, 80 m, 16.ix.2007, leg. Short, García, & Joly, morichal/rock outcrop, AS-07-015 (5 exs., SEMC); same locality but 8.vii.2010, leg Short, Tellez, Arias, small stream on outcrop, VZ10-0708-01B (4 exs., SEMC; includes one ex. mounted on SEM stub); same locality but 9.vii.2010, leg. Short, Tellez, Arias, seeps and stream at night, VZ10-0709-03A (4 exs., SEMC); ca. 15 km NE Pijiguaos, 6°57.904'N, 66°36.392'W, 51 m, 9.vii.2010, leg. Short & Tellez, rock outcrop, detritus flotation, VZ10-0709-01B (1 ex., SEMC).

Differential diagnosis.

This small species may be easily distinguished by the combination of its very pale dorsal coloration and lack of impressed elytral striae (Fig. 3B). The aedeagus is also unique among Tobochares for its outwardly bent parameres (Fig. 14F). Only T. canaliculatus is also nearly as pale, but the elytra of that species are deeply grooved. Tobochares canthus is not typically as pale as T. pallidus , and T. canthus can be further distinguished by its deeply emarginated eyes.

Description.

Size and form: Body length 1.5-1.9 mm. Body elongate oval, moderately dorsoventrally compressed. Color and punctation. Dorsum of head very pale brown; maxillary palps pale (Fig. 7C). Pronotum very pale brown; elytra very pale brown and somewhat transparent. Meso- and metathoracic ventrites brown, and abdominal ventrites very dark brown (nearly black), with prosternum distinctly paler; epipleura, legs, labial palps, and antennae pale. Ground punctation on head, pronotum and elytra moderately fine. Head. Eyes measuring ~100µm anteroposteriorly, continuous with outline of head, emarginate at lateral margin, narrowing to roughly half the width (Fig. 6 A–B). Thorax. Elytra with ten rows of serial punctures, not impressed into groves (Fig. 11D). Metafemora mostly glabrous on ventral face, with narrow band of pubescence along proximal third of anterior margin (Fig. 12C). Elevation of mesoventrite forming a low transverse carina, not quite elevated to the same plane as the ventral surface of the mesocoxae (Fig. 9C). Metaventrite with distinct median ovoid glabrous area that is half to slightly more than half of the total metaventrite length, and about half as wide as it is long (Fig. 10C). Abdomen. Abdominal ventrites uniformly and very densely pubescent, with small spicules interspersed amongst the setae (e.g. Fig. 13A). Aedeagus (Fig. 14F) with parameres relatively narrow, nearly half as narrow as the median lobe; parallel sided in a little more than basal half, then narrowing and bent outwards in apical third; apex of parameres bluntly rounded and about equal to the length of the median lobe; gonopore situated at the tip of the median lobe.

Etymology.

Named for the species’ relatively pale body coloration.

Distribution.

Known from several localities along the northwestern shoulder of the Guiana Shield in Venezuela (Fig. 15).

Biology.

All six collecting events of this species were from rock seepages. The type locality and longest series of specimens were collected on a rock seepage along the margin of the Rio Coromoto (Fig. 18 A–B). The seepage drains water from the surrounding area and is not fed directly by the creek itself. The rock surface had scattered leaves and detritus, as well as algae in some patches. Other collections were on more isolated and seasonal seeps that are only flowing in the wet season (Fig. 18D).

Remarks.

Because this species co-occurs with several other Tobochares in Venezuela, the extremely pale coloration makes specimens easily confused for teneral individuals of other species in the field until they can be examined under higher magnification.