Hemicrepidius indistinctus (LeConte, 1853)

Etzler, Frank E., 2020, A Revision of the Genus Hemicrepidius Germar, 1839 (Coleoptera: Elateridae) of the New World, with Comments on Global Classification, The Coleopterists Bulletin (mo 18) 74, pp. 1-126 : 46-47

Hemicrepidius indistinctus (LeConte, 1853)

( Figs. 21a–e , 23a )

Asaphes indistinctus LeConte 1853: 451 ; Horn 1880: 73; Blatchley 1910: 769.

Hemicrepidius indistinctus (LeConte) : Leng 1920: 170.

Diagnosis. Hemicrepidius indistinctus can be distinguished from all other species of Hemicrepidius by the simple pronotal punctation separated by 1× to 3× puncture diameter, broadly concave frons, and the ear-like posterior margin of the hypomeron where the pronotal hind angle is only visible ventrally as a small projection at the tip.

Hemicrepidius indistinctus is most easily confused with H. decoloratus and H. hemipodus . The characters to distinguish these species are given in their diagnoses above.

Redescription. Length 11.5–15.0 mm, width 3.0–4.0 mm; color uniformly dark red-brown to dark brown, elytra not contrasting with pronotum, sometimes legs, antennae, posterior edge of pronotum paler, ventral side usually paler, particularly along edges of elytra and edges of abdominal ventrites; integument shining. Setae moderately long, depressed, gray or yellow. Head: Punctures subumbilicate, separated by half a diameter to a diameter of a puncture, sometimes punctures sparser in areas; frons weakly to moderately concave anteromedially in dorsal view, some with slight triangular impression medially; frontal carina complete, nearly transverse to broadly rounded in view from front, frontoclypeal region complete and narrow medially, at most weakly projecting; eyes large and strongly bulging, ocular index 56–65 (n = 3); antenna weakly serrate, antennomere 2 subcylindrical, antennomere 3 subcylindrical and 1.25× length of 2 and with similar punctation, antennomere 3 two-thirds length of 4, antennomeres 4–11 about 3× longer than wide, each with subtle medial line bearing less setae than edges, antennomere 11 oval, tip at most slightly constricted, antenna reaching pronotal posterior edge to passing by 2 antennomeres. Prothorax: Pronotum as wide as long to just over 1.1× wider than long, widest at midlength; sides weakly to broadly arcuate, gradually narrowing anteriorly; hind angles almost subparallel, appearing slightly divergent due to sinuate lateral edge anterior of hind angle, dorsal carina thin, directed anteromedially; punctures smaller than punctures on head, appearing simple, separated by one to two diameters of a puncture on disc, punctures slightly closer laterally, most appearing simple, separated by half to one diameter of a puncture; posterior edge with sublateral notches. Hypomeron with subumbilicate punctures, punctures larger than lateral pronotal punctures, nearly contiguous on anterior half, often becoming slightly less dense towards impunctate area on posterior one-fifth; posterior margin ear-like ( Fig. 21c ) so hind angle not visible in lateral or ventral view except for small truncate projection dorsolaterally. Prosternum with punctation smaller than punctation on hypomeron, appearing simple, separated by half a puncture diameter throughout; anterior lobe slightly deflexed, broadly rounded, short, partially covering ventral mouthparts; prosternal process slightly curved dorsad between procoxae, narrow and straight past procoxae. Pterothorax: Mesoventral cavity with lateral edges sinuate, not visible anteriad mesocoxae in lateral view; posterior edge of cavity narrowly truncate. Metaventrite with punctures smaller than punctures on hypomeron, appearing simple, separated by half to one puncture diameter throughout. Scutellar shield elongate, about twice as long as wide, narrowly rounded posteriorly, sides sinuate, dorsal surface weakly to moderately convex, anterior margin nearly straight, setae radiating from midline, denser than setae on elytra. Elytral striae weakly impressed basally; interstriae flat to slightly convex at most, punctation small but giving wrinkled appearance; basal carina simple. Legs with tarsomere lobes narrow, difficult to see dorsally, lobe on tarsomere 3 largest, lobe on tarsomere 2 second largest, lobe on tarsomere 1 small, visible laterally, lobe on tarsomere 4 minute, in most visible only ventrally. Abdominal ventrites: Punctures simple, similar in size to punctures on metaventrite, separated by less than one puncture diameter, uniform throughout; fifth ventrite broadly rounded; lateral edge of each ventrite with microserrations small, but visible under high magnification (50×). Male genitalia ( Figs. 21d, e ): Parameres subparallel laterally on basal three-fourths, sinuate laterally on apical onefourth basad of apical expansion, apical expansion acute and sharply pointed laterally; apex of paramere pointed, slightly membranous, setose ventrally. Median lobe broadly triangular, basal struts straight and directed latero-basally. Basal piece with membranous area roughly transverse medially.

Distribution. Specimens were examined from the following states: UNITED STATES: AL, FL, GA, MS, NC, SC, TN ( Fig. 23a ).

Notes. This species appears to be relatively uncommonly collected and limited to the southeastern United States. It is likely closely related to H. decoloratus , but it can be readily distinguished by the morphological characters in the diagnosis above.

An observation I made in collections is the prevalence of H. ruficornis specimens identified as H. indistinctus . The species key by Horn (1880) likely led many identifiers to this confusion, as they both share the characters given by Horn in the key. Hemicrepidius ruficornis specimens are quite distinct from H. indistinctus , and with the figures (compare Figs. 21a, b with Figs. 36a, b ) and key above, should no longer be misidentified.

No larvae have been associated with this species.

Types Examined. Of Asaphes indistinctus : H. indistinctus , LeC, Ga/ Type #2614; male[?]; type locality Georgia; in MCZC.

Horn Collection (1, MCZC). S. C. [South Carolina].

Specimens Examined (16). UNITED STATES: Alabama: Colbert Co., Barton , VI-9-14-1937 / Van Dyke collection (1, CASC [ Fig. 21c ]) . Florida: Walton Co., Eglin AFB, Range Rd 205, 4.5 mi W Hwy 331, 16-VI-1995, P. E. Skelley et al., MV and blacklight (1, FSCA) . Georgia: [no data] (1, MCZC) ; [Fulton Co.], Atlanta, VI-14 [ Fig. 21b ], V- 29-[19]29, VI-14-[19]39/ P. W. Fattig (3, FMNH [ Fig. 21a ]); Stephens Co. , VII-4-[19]64, L. A. Cambre (2, FMNH [ Figs. 21d, e ]) . Mississippi: Yalobusha Co., Water Valley , 10-20-VII-1971, Michael Horan, Malaise Trap (2, FSCA) . North Carolina: [Moore Co.], Southern Pines, A. H. Manee , VI-6-1914 (1, CASC) . South Carolina: [no data] (2, MCZC) ; Anderson Co., Clemson Experimental Forest , Big Oaks, N 34.612825, W82.824433, at light, 5 July 2018, Anthony Martin Deczynski (1, AMDC) . Tennessee: Benton Co., VI- 8-1950, VI-22-1950, Thomas J. Walker, Jr. (2, FSCA) ; Great Smokey M. N. Pk , VI-23-[19]42/ D. J. and J. N. Knull Collrs (1, FMNH) .

Figures

Fig. 21. Hemicrepidius indistinctus. Dorsal habitus: a) Male, b) Female. c) Pronotum, lateral view. Male genitalia:

Fig. 23. Distribution maps of examined Hemicrepidius specimens (blue/gray dots). a) H. indistinctus, b) H. melanopthalmus.

Fig. 36. Hemicrepidius ruficornis. Dorsal habitus: a) Male, b) Female. c) Pronotum, lateral view. Male genitalia: