Pleocoma laker Marshall, 2018

Marshall, Christopher J., 2018, Two new species of rain beetle (Coleoptera: Pleocomidae: Pleocoma Le Conte, 1856) in the Pacific Northwest of the United State of America, Zootaxa 4471 (2), pp. 387-395 : 388-391

Pleocoma laker Marshall , new species

Figures 1–4 .

Type material. Holotype: OSAC _0001008731, pinned adult male, labeled “ USA: Washington, Klickitat Co., Pine Forest Road, 10.65 km NW Goldendale, 11 March 2017; emerging from holes before sunrise ~6am, 45.889° N 120.920° W. 627 m elevation; C. J. Marshall & Eric Eisel ”; one metathoracic leg removed prior to mounting and stored in 100% ethanol for DNA extraction. Deposited at the Oregon State Arthropod Collection Corvallis, Oregon .

Type locality. United States of America, Washington, Klickitat County, 10.65 km NW Goldendale, 45.889°N, 120.920°W ( Fig. 5 ).

Paratypes. Thirteen males and one female. Nine males with the same label data as holotype: ( OSAC _0001008413– OSAC _0001008419, OSAC _0001008730, OSAC _0001008744); one female ( OSAC _000108424) and four males ( OSAC _000108420– OSAC _000108423): with the same locality data as holotype, 21 March 2017, Michael McBride. Deposited at the Oregon State Arthropod Collection, Corvallis , Oregon .

Diagnosis. This species is easy to distinguish based on males, which may be separated from all other known Pleocoma by the following combination of characters: antennal club with 7 antennomeres, densely setose scutellum, anterolateral areas of pronotum lacking setae and covered in small punctures and with medial longitudinal pronotal groove bearing dense setae that diminish in number anteriorly so as to be absent anteriorly; body color a monochromatic dark mahogany brown. Males are most similar in general appearance to those of P. minor and P. dubitabilis dubitablis Davis, 1935 , but may be easily distinguished by the setation of the pronotal midline, which in P. minor and P. dubitabilis dubitablis is typically absent or represented only by scattered weak setae. Although the female does bear similarities to the male in many of the above traits, an explicit diagnosis based on female characters will have to wait until a more thorough examination of other female Pleocoma species can be undertaken.

Description. Male: habitus oval rounded, macropterous, dark mahogany brown in color; length between 23– 27 mm (holotype: 26 mm) from apex of frontoclypeal horns to median apex of elytra ( Fig. 1A ).

Head ( Fig. 2A ): bearing simple prominent central dorsal tubercle (horn) of variable height; dorsum of frons heavily punctate, punctation extending posteriorly from anterior edge between tentorial pits to base of central tubercle and posterolateral area of head and gena, each puncture bearing a long, erect, golden seta; clypeus enlarged with distinct lateral and anterior faces, anterior face large, forked dorsolaterally into the aforementioned well-sclerotized, horn-like apices, narrowed ventrally where it meets labrum perpendicularly, covered with setose punctations; ocular canthus large, most commonly subquadrate when viewed dorsally but highly variable, less punctate than frontoclypeal area, with only a few scattered setae; eyes large. Mouthparts: labrum small, convex, and covered in dense setation and fused to clypeus, shape in most individuals smoothly acuminate, often with a distinctly more sclerotized apex and in a few males a dorsomedial tooth; mandibles smaller than labrum, typically visible from above at sides of labrum; maxillary palpus with 4 palpomeres, 2nd palpomere elongate held vertically with 3rd palpomere extending anteriorly from apex; galea small, blunt, covered in setae; mentum weakly trapezoidal, convex, densely punctate and setose; prementum reduced to a narrow transverse band visible dorsad to medially approximate bases of labial palpi; labial palpus with 3 palpomeres; gula prominent, central area glabrous and shiny, anterior region (=submentum) punctate; antennae with 11 antennomeres, terminating in a 7-antennomere lamellate club, 2nd antennomere less than 1/4th length of third.

Thorax: pronotum wider than long, anterior angles rounded or weakly angled, posterior angle rounded, with a longitudinal medial groove spanning entire length, marginal groove entire, broken only for a short span at posterior end of longitudinal medial groove, pronotal surface covered in small punctures, separated by their own diameter or greater, punctation becoming dense along longitudinal groove and bearing long setae in posterior 2/3rd, anterior portion of groove lacking setae or occasionally with a few short setae; hypomeron heavily punctate and covered in setae; prosternum narrow, medially setose, laterally shiny, procoxal cavities open posteriorly; scutellum rounded and densely setose; elytra shiny with 9 visible punctate striae; sutural stria (stria 1) deeper than others with clear punctures throughout, defines a strongly convex interval (interval 1); remaining striae comprised of slightly oblique rows of small punctures arranged in four pairs that either fuse apically with each other or terminate before the posterior margin of elytra; first three strial pairs (2–3, 4–5, and 6–7) fully visible dorsally, fourth (8–9) anteriorly visible only in lateral view; interstriae with scattered small punctures, elytral margin with complete row of setae.

Legs: ( Fig. 3 ) procoxa large, prominent and nearly contiguous articulating with well-sclerotized, setose trochantin; profemur anteriorly covered in fine, setose antennal brush; protibia of holotype with 5 marginal teeth, but males can possess 3–7 such teeth, the first two of which may be quite small, internal tibial apex with single sharp tooth; protarsus with 5 elongate tarsomeres, pretarsus with long simple claws and bisetose sclerotized arolium; mesocoxa prominent, articulating with a small, narrow mesotrochantin, separated by narrow mesosternal process; mesofemur with heavy setation; mesotibia typically with 1 or 2 small teeth on proximal half, posteromedial teeth forming a transverse ridge, apex surrounded by small teeth and armed with two large spines at base of tarsus; mesotarsus as in prothoracic leg; metacoxa transverse with a distinct medial groove and pit, metatibia as in Figure 3C , metatarsus similar to mesotarsus.

Abdomen: 6 visible sternites; aedeagus as in Figure 4 .

Female: (29 mm), wingless; antennal lamellae short forming a rounded ‘club’, eyes smaller and in general more heavily sclerotized than male with shorter, finer, less dense setae; central tubercle of head small and distinctly bifid; pronotum with larger and more densely arranged punctures than in male; medial pronotal groove with setae for entire length; scutellum rounded, with only scattered setae; protibia more developed than in male, with 5 wide external teeth.

Distribution. Currently the species is known only from the forested areas west of Goldendale, Washington that consist predominantly of ponderosa pine ( Pinaceae : Pinus ponderosa ) and Garry oak ( Fagaceae : Quercus garryana ). However, it is likely that further surveys in the surrounding region will uncover additional populations.

Natural history. Mating flights of this species occur in the early morning hours of late winter and early spring (January-March) when snow is patchy and melting. Males have been seen flying between in the pre-dawn morning hours when air temperatures were cold but above freezing (2–7 °C) and females were active at the surface. Flight activity of males appeared to drop off dramatically after sunrise. The population around the type locality appears to be sizeable; emergence holes of adults were not uncommon and small (30 cm x 30 cm) holes dug in the wet ground in areas with emergence holes reliably uncovered multiple larvae at various instars.

Etymology. This species is named in honor of its true discoverer: Laker ( Fig. 6A), the loyal chocolate Labrador Retriever belonging to Linda and Michael McBride. Not only was it Laker’s keen nose and fondness for consuming early spring rain-beetles that brought this population to the attention of his owners, but the reddish chocolate-brown color of this species harkens the color of Laker’s own coat. This name should be treated as a noun in apposition.

Figures

FIGURE 1. Habitus photographs of exemplar specimens (not type material). Males: A, Pleocoma laker Marshall, new species; B, P. callisto Marshall, new species. Females: C, P. laker Marshall new species; D, P. callisto Marshall new species.

FIGURE 2. Head and pronotum, male dorsal; A, P. laker Marshall new species; B, P. callisto Marshall, new species; C, P. crinita Linsley, 1938 paratype; D, P. crinita Linsley, 1938 paratype labels

FIGURE 3. Pleocoma laker Marshall, new species, A, Protibia and tarsus; B, mesotibia and tarsus; C, metatibia and tarsus.

FIGURE 4. Pleocoma laker Marshall, new species, male genitalia. A, dorsal; B, lateral view.

FIGURE 5. Type localities for Plecooma species in the vicinity of the Columbia River. Green circle: Pleocoma dubitabilis dubitabilis (Oregon, Forest Grove/Dilley); black hexagon: Pleocoma dubitabilis leachi (Oregon, Colton); red star: Pleocoma callisto (Oregon, Hood River, vicinity Oak Grove); yellow circle: Pleocoma minor (Oregon, Hood River); white circle: Pleocoma crinita (Washington, Glenwood); white square: Pleocoma oregonensis (Oregon, The Dalles); yellow star: Pleocoma laker (Washington, NW of Goldendale).