Polycentropus stephani Bowles, Mathis, and Hamilton, 1993

Orfinger, Alexander Benjamin, 2023, Taxonomic revision of the Polycentropus confusus species group (Trichoptera: Polycentropodidae), Journal of Natural History 57 (41 - 44), pp. 1825-1916 : 1889-1893

Polycentropus stephani Bowles, Mathis, and Hamilton

( Figures 32–33 , 52 )

Polycentropus stephani Bowles, Mathis, and Hamilton, 1993: 31–32 , figs. 1–3, J; fig. 4, ♀; type locality ′Logan Co., Mt . Magazine, Green Beach , Gutter Rock Creek ̍ ( NMNH). Polycentropus species B and C Bowles and Mathis, 1989: 237.

Polycentropus stephani Moulton and Stewart, 1996 : figs. 557, 560–561, J.

Diagnosis. Males of Polycentropus stephani are distinguished from all other males of the P. confusus species group by the presence of a caudally directed basoventral spur on the phallus. The basodorsal processes of the inferior appendages are similar to those of P. chelatus and P. neiswanderi in being somewhat finger-like, but differ from those two species by the small basoventral protuberance.

Females of P. stephani are most similar to those of P. chelatus in respect to the posterior apex of external parts of gonopods VIII appearing elongate and digitiform in lateral view and in the internal parts of gonopods VIII being smooth, and to females of P. pixi in the general shape of the smooth internal parts of gonopods VIII and the ventral plates being convergent. From females of P. chelatus , those of P. stephani are distinguished by the sinuous margins of the posterior apex of external parts of gonopods VIII, the convergent and semi-elliptical ventral plates, and the apparent absence of the sclerotised anterior part of the genital chamber. From females of P. pixi , females of P. stephani are distinguished by the convergent internal parts of gonopods VIII, the posterior apex of external parts of gonopods VIII appearing digitiform in lateral view, and the apparent absence of the sclerotised anterior part of the genital chamber.

Adult description

General. Length. of male 5.1–6.0 mm (mean = 5.6 mm; n = 5). Length of female 5.9– 7.0 mm (mean = 6.4 mm; n = 4).

Male genitalia ( Figure 32A–E ). Abdominal segment VIII annular. Terga IX and X fused, membranous, extended caudad over bases of intermediate appendages. Sternum IX subovoid in lateral view, posterior margin slightly sinuous. Intermediate appendages originating beneath terga IX+X and extending beyond them, curved ventrad apically, their apices each bearing 3 small setae; in dorsal view apices proximate, parallel. Bodies of pre-anal appendages each with round caudal margin, subtriangular posteroventral corner, deep dorsal emargination, dorsal process long, curved ventrad, extending below apex of head of basodorsal process of corresponding inferior appendage, acute apically; in dorsal view slender, elongate, subparallel, apices incurvate. Inferior appendages in lateral view each with digitiform basodorsal process erect, elongate, round dorsally, with basoventral protuberance, curving slightly caudad beyond protuberance, main body of appendage with dorsal and ventral margins subparallel along length to round subtly upturned apex extended posterad, terminating slightly anterad to intermediate appendages; in ventral view subparallel to roughly mid-length, divergent beyond mid-length, each wide basally, inner margin sinuous basally to about mid-length, distally tapering beyond mid-length to round apex, basodorsal process mostly hidden by main body of inferior appendage, anterior apex projecting beyond medial margins, posterior apex projecting beyond lateral margins, in cleared specimen broad, oblong, apices round; in caudal view subtriangular, with medial projection round. Phallus a fully sclerotised tube, depth approximately uniform along length, bearing prominent caudally directed basoventral spur, curved about 80° ventrad at apex, apical section subtriangular, internal spinules absent, internal phallic sclerite long, horizontal, with round apices.

Female genitalia ( Figure 33A–B ). Venter VIII in ventral view with ventral plates convergent, broad, semi-elliptical, tapering apically, covered with setae; in lateral view each terminating in round posterior apex; posterior apex of external parts of gonopods VIII in ventral view with posterior margin subtriangular; in lateral view digitiform, dorsal and ventral margins sinuous, subparallel, extending beyond ventral plates with round apex; internal parts of gonopods VIII in ventral view visible through venter VIII even in uncleared specimen, appearing smooth, darker than surrounding tissue, convergent, subrectangular, with broad posterior apices slightly anterior of apices of ventral plates, anterior ends tapered, not extending to sclerotised external part of gonopods VIII at basal third of ventral plates; in ventral view anterior part of genital chamber apparently absent; processus spermathecae subovoid with distomesal elevation bearing opening of ductus spermathecae.

Larva. Unknown.

Pupa. Unknown.

Biology. Little is known of the biology of this apparently rare and seldom collected species. Adults have been collected using UV light traps from April to May near intermittent streams and small perennial streams with rocky substrate present. This species is often collected with the much more common species Polycentropus centralis .

Distribution ( Figure 52 ). USA: Arkansas.

This species appears to be endemic to the interior highlands of Arkansas.

Material examined. Holotype: USA. Arkansas: Logan County, Mount Magazine, Green Beach , Gutter Rock Creek , UV light, R. Leschen coll., 1-v-1987, 1 male (USNMENT01507918) . Paratypes: USA. Arkansas: Independence County, unnamed intermittent stream, 18-iv-1987 coll ., P.A. Harp , 1 male (USNMENT01507921) . Logan County, Mt . Magazine, Green Beach, Gutter Rock Creek , UV light, R . Leschen coll ., 1-v-1987, 1 male, 1 female ( FSCA) . Washington County, Devils Den State Park , black light, C .E . Carlton coll., 22-iv-1989, 1 male, 1 female (USNMENT01507922), 1 male, 1 female (USNMENT01507923).

Allotype: USA. Arkansas: Logan County, Mount Magazine, Green Beach , Gutter Rock Creek , UV light, R. Leschen coll., 1-v-1987, 1 female (USNMENT01507924).

Non-type material. USA. Arkansas: Polk County, Route 71, north of Mena, O. Flint coll., 1 v-1958, 1 male, 1 pupa (lacking case and shed sclerites) (USNMENT01507925). Saline County, South Alum Creek , [N34°47 ʹ 00.96″, W93°01 ʹ 53.04″], A.L. Sheldon coll., 2-v-2001, 2 males, 15 females ( ECC 3.478 ) .

Figures

Figure 32. Polycentropus stephani Bowles, Mathis, and Hamilton, 1993, male genitalia (holotype). A. left lateral (with phallus removed); B. dorsal; C. segment IX and inferior appendages, ventral; D. phallus, left lateral; E. dorsobasal process of right inferior appendage, caudal. Abbreviation: b.v. s. = basoventral spur.

Figure 33. Polycentropus stephani Bowles, Mathis, and Hamilton, 1993, female genitalia. A. left lateral; B. ventral.

Figure 52. Known Canadian province and US state distribution of Polycentropus stephani Bowles, Mathis, and Hamilton, 1993, as indicated by grey shading.