Ochthebius (Asiobates) cascadeus, Perkins, 2023

Perkins, Philip D., 2023, New Neotropical and Nearctic species of water beetles in the genera Hydraena Kugelann and Ochthebius Leach, a key to North American genera and subgenera of the family, new distribution records, and a synopsis of ecology, behavior and morphology related to aquatic life (Coleoptera: Hydraenidae), Zootaxa 5367 (1), pp. 1-86 : 57-61

Ochthebius (Asiobates) cascadeus , new species

Figs. 4 (habitus comparison), 33 (habitus and aedeagus)

Type Material. Holotype (male): U.S.A.: Washington: “WASH: Pierce Co., Mt. Rainier N.P., West Side Rd. , 3.3 mi N jct Wash 706, 2800’ VII.19.1975 // muddy and gravelly banks, lg. stream // A. Newton & M. Thayer collectors” ( FMNH) . Paratypes (15): Same data as holotype (11 FMNH) ; Oregon, Clackamas Co., 1.5 mi. S. jct. US 26 and Ore 35, flood debris, forest stream, 11.vii.1975, leg. A. Newton & M. Thayer (3 FMNH) ; Washington, Olympic Nat. Pk., Queets Ranger Sta., 15.v.1968, leg. Campbell & Smetana (1 MCZ) .

Differential Diagnosis. This reddish, very convex species will key to O. mimicus Brown in Perkins (1980: 303). The male genitalia clearly show the relationship of the two species, while differing significantly from each other in the shape of the distal piece ( Fig. 33 ). Reliable determinations will require dissection of males.

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.67/0.88; head width 0.52; pronotum 0.48/0.79, PA 0.62, PB 0.53 (PB = sclerotized portion only); elytra 1.00/0.88. Habitus as illustrated ( Fig. 33 ). Form ovate, very convex. Pronotum and elytra dark reddish brown, dorsum of head dark brown; legs and palpi light reddish brown. Frons coarsely densely punctate, some punctures confluent, interstices shining; interocular foveae deep and large, width of each slightly greater than distance between them; interocular tuberculi large, large depression between interocular tuberculi and eye; basomedial fovea smaller and shallower than interocular foveae. Frontoclypeal suture evenly arcuate. Clypeus length 0.50 width; medially very finely very sparsely punctulate, shining, laterally more densely punctulate and microreticulate. Labroclypeal suture weakly bisinuate. Labrum length 0.33 width; very finely sparsely punctate, very finely pubescent; anterior margin with deep apicomedian notch, edge very weakly upturned. Maxillary palpus with palpomere 3 moderately wide; palpomere 4 distinctly less than 0.50 length of penultimate. Lateral margin of mandibles (male) without spines.

Pronotum with anterior hyaline border moderately wide in front of disc, slightly wider in front of lateral fossulae, then tapered to anterior angles. Lateral hyaline border origin at anterior angles, extended narrowly along lateral depressions, broad in region of posterior excavation, very narrow around posterior margin. Anterior margin of pronotum trisinuate, with emargination in front of each lateral depression; anterior angles rounded, obtuse. Lateral depressions not appearing inflated, broad, with very shallow, sparse punctures; margins arcuate, irregular; posterior extremes excavate and with small tooth; pronotum markedly constricted behind lateral depressions. Lateral fossulae deeply impressed; inner margin abrupt, posterior extreme ended before lateral hyaline border. Pronotal disc very convex, punctures in interfoveal area large, dense, irregularly sized, separated at most by 1xpd, usually separated by ca. 0.5xpd or thin walls; each puncture with very short seta; surface between punctures smooth and shiny. Median groove deeply impressed, micropunctulate; widened at anterior and posterior. Anterior foveae moderately large. Posterior foveae very large, deep, with diagonal orientation.

Elytral disc without depression in midregion, shiny, with six rows of punctures between suture and humeri. Longitudinally and transversely very convex, appearing humped at posterior declivity, at midlength; punctures round, ca. 1xpd of largest pronotal punctures; intervals rounded, slightly elevated, width ca. 2–3xpd, with very shallow surface irregularities; interstices between punctures ca. 1–2xpd; each puncture with very short decumbent seta. Explanate margin moderately wide. Elytral apices separately rounded.

Venter: Mentum moderately shining, with moderately dense moderately fine setigerous punctures, setae short, inconspicuous except longer and denser at anterolateral angles. Prosternum hydrofuge pubescent, with strong median carina. Metaventrite hydrofuge pubescent laterally, with large suboval slightly angulate anteriorly shining with glabrous area on disc. Abdominal ventrites 1–5 hydrofuge pubescent. Ventrite 6 moderately shining, anterior ½ effacedly microreticulate, posterior ½ with with sparce, short setae. Last tergite rounded apically, with short setae. Protarsomeres 1–3 (male) with large pad of suction setae.

Distribution. Currently known only from several localities near the type locality at Mt. Rainier National Park.

Etymology. Named in reference to the geographical distribution, the Cascade Mountains.

Remarks. The aedeagal distal piece of O. mimicus Brown is illustrated herein ( Fig. 33 ), from a specimen collected in Oregon, Wasco County. A line drawing of the entire aedeagus is given in Perkins (1980: 387).

New distribution records

New distribution records are provided for species that have range extensions, and/or for species that were previously known from very few specimens, to document the new collection records and to record new museum depositions. All new records below are represented by at least one, and usually more, dissected male specimens.

Previously published collection/depository and distribution information presented below are summerized from Perkins (1980). The citations for original publication of names, which are presented in the new distribution records section, are given in Perkins (1980). Specimen records in Perkins (1980) with the depository given as PDP have all been donated to the MCZ.

Figures

FIGURE 4. Dorsal habitus of species of Ochthebius.

FIGURE 33. Ochthebius (Asiobates) cascadeus, new species, holotype habitus and aedeagus (inset:aedeagal apex of Ochthebius (Asiobates) mimicus Brown).