Athoplastus palouse Etzler and Johnson, 2018

Etzler, Frank E. & Johnson, Paul J., 2018, Athoplastus Johnson and Etzler (Coleoptera: Elateridae: Dendrometrinae), a New Genus of Click Beetle from the Northwestern Continental USA, The Coleopterists Bulletin 72 (3), pp. 503-521 : 516-517

Athoplastus palouse Etzler and Johnson , new species

(Adult: Figs. 2 , 14 , 25–27 )

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Diagnosis. This species can be distinguished from other Athoplastus species by the combination of the non-compressed prosternum ( Fig. 8 ), dense pronotal punctation ( Fig. 10 ), and elytra without dark markings along the striae of the elytra. More subtle characters that help distinguish this species are the more parallel-sided pronotum ( Fig. 2 ) and the slightly wider antennomeres ( Fig. 14 ). These last two characters are best used when comparing specimens of different species and become quite clear in this way. However, when identifying just a single specimen, these characters are less useful, so the characters from the key should be used to eliminate other potential species. This species is quite similar to A. rainieri , but the paramere tips and V-shaped membranous area of the basal piece of the male genitalia ( Figs. 25–27 ) and geographic distribution, in addition to the subtle characters above, will distinguish these two species.

Description. Male. Length 15–17 mm in length, width 3–4 mm (measured across bases of elytra). Red-brown to brown, carina, palps, and tips of mandibles darker; posterior margin of hypomeron, coxae, and tarsi lighter, almost tawny yellow ( Fig. 2 ). Head: Ocular index = 60.0–68.4 (mean = 65.0, n = 3). Antennae: Mean ratio of antennomeres 2- 11: 1: 1.25: 3.4: 3.6: 4; 4: 3.8: 4: 5.2 (n = 2). [Note: Antennomeres 8–11 are adjusted values based only on one specimen. The antennomeres, on average, are less narrowed than in other species. This is difficult to describe, so compare Fig. 14 to Figs. 12 and 13 .] Pronotum: 1.4–1.6X wider than long. Lateral margin completely carinate, subparallel anterad divergent hind angles; subtly dorsoventrally flattened along lateral edges near anterior fourth. Punctures distinct, simple and dense on disc, separated by at most 1 diameter, often by about 0.5X diameter of puncture; punctures becoming denser along margins, nearly continuous laterally. Prosternum: Slightly convex with dense, shallow, subumbilicate punctures; anterior lobe short, broadly rounded, shallowly deflexed. Posterior process short and arcuate, gradually raised ventrally between procoxae, then deflexed posteriorly. Legs: Tarsomere 5 equal to tarsomere 1 on all tarsi. Elytra: Elongate, subparallel, 4.0–4.5X pronotal length; striae shallowly impressed, deeper apically; intervals flat, punctures fine, shallow, and irregularly distributed. Aedeagus ( Figs. 25–27 ): Basal piece 2/5 total length, with broadly triangular membranous section on ventral surface ( Fig. 26 ); median lobe 1.3X length of parameres, slightly deflexed ventrally at tip, median carina on ventral surface, basal struts following edges of median lobe; parameres wide basally, edges slightly sinuate and gradually narrowing toward tip, tip with very acute lateral expansion bearing 2 setae ( Fig. 27 ).

Female. Unknown.

Specimens Examined (8). Holotype. USA: WASHINGTON: [Whitman Co.], Pullman, 7.vi. [18]98, C. V. Piper (1, WSUC) . Paratypes. USA: IDAHO: Kootenai Co., Athol , 29.iv.1957, W. F. Barr Collector (1, WFBM) . WASHINGTON: Washington T[erritory] (1, USNM) ; Pullman, Sept. [year unknown] (1, USNM) ; [Whitman Co.], Pullman , 8.vi.[18]99 (1, WSUC) ; Pullman , 31.iii. [19]11 (1, WSUC) ; Pullman , 01.iv.[19]17 (1, USNM) ; Pullman, Apr [il] [19]20, Chester Dixon (1, USNM) ; Kamiak Butte , 23.ii.[19]34 Wn, J.F. Clarke (1, USNM) .

Distribution. This species is only known from the areas of Pullman, Washington and Athol, Idaho ( Fig. 29 ).

Etymology. The specific name “ palouse ” is a noun in apposition derived from the geographic area of collection of the majority of specimens.

Taxonomic Remarks. The distance between localities is quite a surprise, but the morphology of specimens from the two localities is consistent. Athoplastus palouse may co-occur with A. acutus .

Figures

Figs. 1–4. Athoplastus species, dorsal habitus. 1) A. acutus; 2) A. palouse; 3) A. lochsa; 4) A. rainieri.

Figs. 10–15. Athoplastus species. 10) A. acutus, prothorax, dorsal view; 11) A. lochsa, prothorax, dorsal view; 12) A. acutus, left antenna; 13) A. lochsa, left antenna; 14) A. palouse, left antenna; 15) A. acutus, female, left wing. Scale bars for antennae = 1 mm; for wing = 5 mm.

Figs. 16–27. Athoplastus species, adeagi, dorsal view, ventral view, and close up of paramere apex, respectively.

Figs. 5–9. Athoplastus species. 5) A. acutus, female dorsal habitus; 6) A. acutus, male dorsal habitus, darker coloration; 7) A. acutus, male ventral habitus; 8) A. rainier, prothorax, lateral view (arrow indicates start of area between procoxae); 9) A. acutus, prothorax, lateral view (arrow indicates start of expanded area between procoxae).

Figs. 28–30. Athoplastus species. 28) A. rainier, female, internal genitalia, v = vagina, u = uterus, acgld = accessory gland, bc = bursa copulatrix (after Han et al. 2012); 29) Distribution map of examined specimens, with rivers; 30) Neighbor-joining tree of Montana populations of A. acutus, COI mtDNA, 500 runs, scale bar = 1% difference.