Polycentropus chenoides Ross and Yamamoto, 1965

Orfinger, Alexander Benjamin, 2023, Taxonomic revision of the Polycentropus confusus species group (Trichoptera: Polycentropodidae), Journal of Natural History 57 (41 - 44), pp. 1825-1916 : 1856-1858

Polycentropus chenoides Ross and Yamamoto

( Figures 17 , 43 )

Polycentropus chenoides Ross and Yamamoto, 1965: 243 , fig. 4, J; type locality ′ Oriente, Long Island , New York ̍ ( INHS) .

Polycentropus chenoides Armitage and Hamilton, 1990 : figs. A–D, J.

Diagnosis. Males of Polycentropus chenoides are readily separable from those of all other species of the P. confusus species group by the strongly deflexed basodorsal process of the inferior appendage and the intermediate appendages being strongly curved dorsad, in dorsal view crossing to form an ′X̍ shape.

Adult description

General. Length. of male 6.2–7.1 mm (mean = 6.8 mm; n = 5).

Male genitalia ( Figure 17A–E ). Abdominal segment VIII annular. Terga IX and X fused, membranous, extended caudodorsad over bases of intermediate appendages. Sternum IX subovoid in lateral view, posterior margin sinuous. Intermediate appendages originating beneath terga IX+X and extending beyond them, curved dorsad, their apices each bearing 3 small setae; in dorsal view apices proximate, convergent, crossing to form an ′X̍. Bodies of pre-anal appendages each produced posterad with slightly sinuous posterior margin, deep dorsal emargination; dorsal process long, curved ventrad, terminating above head of basodorsal process of corresponding inferior appendage, acute apically, bearing single seta on ventral margin near apex; in dorsal view slender, elongate, divergent, straight, lateral and mesal margins subparallel for ¾ length, tapering evenly to acute apex beyond for final ¼ length. Inferior appendages in lateral view each with capitate basodorsal process strongly deflected, with moderately long neck and subtriangular head round posterad and projecting ventrad with its pointed apex hidden behind main body of appendage, main body of appendage with broad base, tapering evenly to round apex extended posterad slightly beyond intermediate appendages;in ventral view divergent,each semi-elliptical, wide basally, distally tapering to round apex, margins slightly sinuous, basodorsal process nearly completely hidden by main body of inferior appendage, with only medial round tip exposed, in cleared specimen broad, with medial round projection; in caudal view similar, goose-head shaped, with medial projection round. Phallus a fully sclerotised tube, in lateral view with larger base, curved about 15° ventrad slightly beyond mid-length, apical section subrectangular, internal spinules absent, internal phallic sclerite very small, central, horizontal, ovate.

Female genitalia. Unknown.

Larva. Unknown.

Pupa. Unknown.

Biology. Almost nothing is known of the biology of this seldom collected species. Most specimens have been collected in May, with one male specimen collected in Pennsylvania in September ( Masteller and Flint 1992). All specimens were collected near flowing waters of low-order streams to small, navigable rivers.

Distribution ( Figure 43 ). USA: Delaware, New York, Pennsylvania.

This species is apparently endemic to a few north-eastern US states. Given that R.W. Lake collected several specimens in Delaware near the Maryland border, it is possible that this P. chenoides will eventually be collected from Maryland ̍s Eastern Shore.

Material examined. Holotype: USA. New York: Long Island , R. Latham coll., 13-v-1947, 1 male ( INHS Insect Collection 37,249).

Non-type material. USA. Delaware: Sussex County, Blades , UV light trap, R .W. Lake coll ., 24–2v-1983, 2 males ( CUAC0000107309 ) . 7-8-v-1983, 1 male ( CUAC0000107308 ) . Georgetown, Substation , 18–24-v-1976, 1 male ( CUAC0000107310 ) . Seaford-Blades , 21– 23-v-1983, 1 male ( CUAC0000107311 ) . Site #S-27, town of Smith Hill on Rd . 64 near jct. Rd .457, James Br., [N38°29 ʹ 39.48″, W75°30 ʹ 17.28″], 14-v-1974, 1 male ( CUAC0000107307 ) .

Figures

Figure 17. Polycentropus chenoides Ross and Yamamoto, 1965, 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.

Figure 43. Known Canadian province and US state distribution of Polycentropus chenoides Ross and Yamamoto, 1965, as indicated by grey shading.