Polycentropus neiswanderi Ross, 1947

Orfinger, Alexander Benjamin, 2023, Taxonomic revision of the Polycentropus confusus species group (Trichoptera: Polycentropodidae), Journal of Natural History 57 (41 - 44), pp. 1825-1916 : 1877-1881

Polycentropus neiswanderi Ross

( Figures 26–27 , 49 )

Polycentropus neiswanderi Ross, 1947 : 13,136, fig. 10, J; ♀; type locality ′ Shawnee Forest , Ohio ̍ ( INHS) .

Polycentropus neiswanderi Nimmo, 1986: 197–198 , figs. 153–157, J; figs. 158–159, ♀.

Polycentropus neiswanderi Armitage and Hamilton, 1990 : figs. A–D, J; figs. E–F, ♀.

Diagnosis. Males of P. neiswanderi most resemble those of P. chelatus in the shape of the basodorsal process of the inferior appendage and P. maculatus in the strong ventral curvature of the phallus. From males of P. chelatus , those of P. neiswanderi can be distinguished by the shorter, straighter dorsobasal processes of the inferior appendages, the deep emargination at mid-height of the bodies of the pre-anal appendages, the dorsocaudal round process of the bodies of the pre-anal appendages as seen in lateral view, and the strong ventral curvature of the phallus. From males of P. maculatus , those of P. neiswanderi are distinguished by the digitiform basodorsal processes of the inferior appendages, the incurvate apices of the dorsal processes of the pre-anal appendages, and by the shape of the body of the pre-anal appendages which, in P. maculatus , possesses a subtriangular posteroventral process and lacks any emargination.

Females of P. neiswanderi are most similar to those of P. maculatus in the tiny, ventrally recurved apex of the posterior apex of external parts of gonopods VIII as viewed in lateral aspect and in having wrinkled, elliptical internal parts of gonopods VIII. Females of P. neiswanderi are also somewhat similar to those of P. pentus in overall form. Females of P. neiswanderi can be distinguished from females of both P. maculatus and P. pentus by the shape and orientation of the ventral plates which, in ventral view, appear slender and subparallel rather than broad and convergent. In P. neiswanderi , the ventral plates are semi-elliptical in ventral view, vs subtriangular in P. maculatus . Also, P. neiswanderi females exhibit the tiny, ventrally recurved apex of the posterior apex of external parts of gonopods VIII as viewed in lateral aspect that is absent in P. pentus . Finally, from P. maculatus , P. neiswanderi differs in having a much simpler, slender, semicircular anterior part of genital chamber.

Adult description

General. Length. of male 5.9–6.8 mm (mean = 6.3 mm; n = 5). Length of female 6.1– 7.1 mm (mean = 6.5 mm; n = 5).

Male genitalia ( Figure 26A–E ). Abdominal segment VIII semi-annular. Terga IX and X fused, membranous, extended caudad over bases of intermediate appendages. Sternum IX ovoid in lateral view, posterior margin slightly sinuous with caudoventral lip. Intermediate appendages originating beneath terga IX+X and extending beyond them, curved slightly ventrad, their apices each bearing 5 small setae; in dorsal view apices proximate, subparallel, together appearing bifid. Bodies of pre-anal appendages each with round ventral half, deep emargination at mid-height, small, round dorsocaudal process ventrad of base of dorsal process; dorsal process long, curved ventrad about 90°, extending below apex of basodorsal process of corresponding inferior appendage, acute apically; in dorsal view slender, elongate, subparallel for basal 2/3 length, distally incurvate for final 1/3 length. Inferior appendages in lateral view each with digitiform basodorsal process erect, finger-like, round dorsally, main body of appendage broad with dorsal and ventral margins subparallel, surface with dorsomesal excavation to about mid-length, round apex extended posterad slightly anterior to intermediate appendages; in ventral view subparallel, wide basally, medial and lateral margins subparallel for 1/3 length, medial margin curving outward beyond about 1/3 length to round apex, basodorsal process mostly hidden by main body of inferior appendage, lateral margins extending beyond main body of inferior appendage near apex, in cleared specimen rounded with medial blunt projection; in caudal view oblong, with medial projection round. Phallus a fully sclerotised tube, in lateral view with larger base, curved about 90° ventrad near apex, apical section subrectangular with basoventral lip, internal spinules absent, two internal phallic sclerites each moderately long, vertical, with round ventral base and round dorsal vertex.

Female genitalia ( Figure 27A–B ). Venter VIII in ventral view with ventral plates subparallel, narrow, elliptical, subtly 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 round; in lateral view extending beyond ventral plates in tapered process with its tiny apex recurved ventrad; internal parts of gonopods VIII in ventral view visible through venter VIII even in uncleared specimen, appearing longitudinally wrinkled, darker than surrounding tissue, slightly convergent, semi-elliptical, with round posterior apices distinctly anterior of apices of ventral plates, joined by inverted-U-shaped bridge medially, anterior ends wide, extending to sclerotised external part of gonopods VIII at basal third of ventral plates; in ventral view anterior part of genital chamber sclerotised, slender, semicircular, wrapping around processus spermathecae; processus spermathecae subovoid with distomesal elevation bearing opening of ductus spermathecae.

Larva. Unknown.

Pupa. Unknown.

Notes. The paratype with code INHS Insect Collection 38,137 has characters intermediate between P . chelatus and P. neiswanderi , already two morphologically similar species. The phallus curvature and shape of the body of the pre-anal appendage align more with P . chelatus, while the structure of the basodorsal process aligns with P. neiswanderi . Upon comparing this specimen to the holotype of P . chelatus, Hamilton identified this specimen as P. chelatus . This would represent a new state record (Ohio) for the species . Upon my examination of the specimen and comparison with type material, I am cautiously maintaining the P . neiswanderi paratype designation. In addition, a male specimen of P . neiswanderi listed as collected in Arkansas is included in the NMNH database but could not be found and lacks an accession code . Arkansas would represent a new state record for the species, but without the specimen and with little collection data, this cannot be confirmed. Finally , Houghton et al. (2022) reported P. neiswanderi from Illinois, although upon investigation and communication with the authors, this record is determined to be erroneous and the known distribution of P. neiswanderi is restricted to Ohio and Kentucky.

Biology. Almost nothing is known of the biology of this rarely collected species. Adults have been collected using light traps in April, May and June near small, cool streams. Floyd et al. (2012) classified this species as Threatened in Kentucky.

Distribution ( Figure 49 ). USA: Kentucky, Ohio.

This species is evidently a narrow-range endemic. Dubious or erroneous state records have been reported, as discussed in the Notes subsection above.

Material examined. Holotype: USA. Ohio: Shawnee Forest , light trap, vi-1942, 1 male ( INHS Insect Collection 38,172) . Paratypes: USA. Ohio: Lawrence County, Dean Forest , light trap, C . Neiswander coll ., v-1939, 1 male ( INHS Insect Collection 38,137) . Shawnee Forest , vi-1942, 1 female ( INHS Trichoptera 24,579), 4 males ( INHS Trichoptera 24,578), 1 female ( INHS Insect Collection 38,135), 12 females ( INHS Insect Collection 38,136), 2 males ( INHS Trichoptera 24,577) . Allotype: USA. Ohio: Shawnee Forest , light trap, vi-1942, 1 female ( INHS Trichoptera 24,576) .

Non-type material. USA. Kentucky: Marion County, Tributary of Salt Lick Creek at Salt Lick Creek Rd ., J .K. Moulton coll ., 28-v-2006, 2 males ( FAMU) .

Figures

Figure 26. Polycentropus neiswanderi Ross, 1947, 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 27. Polycentropus neiswanderi Ross, 1947, female genitalia. A. left lateral; B. ventral.

Figure 49. Known Canadian province and US state distribution of Polycentropus neiswanderi Ross, 1947, as indicated by grey shading.