Polycentropus centralis Banks, 1914

Orfinger, Alexander Benjamin, 2023, Taxonomic revision of the Polycentropus confusus species group (Trichoptera: Polycentropodidae), Journal of Natural History 57 (41 - 44), pp. 1825-1916 : 1849-1852

Polycentropus centralis Banks

( Figures 13–14 , 41 )

Polycentropus centralis Banks, 1914: 258 , fig. 67, J; type locality ′St. Louis, Mo̍. (MCZ). Polycentropus centralis Milne, 1936: 85 .

Polycentropus centralis Ross, 1944: 64–65 , fig. 231, larval head and pronotum; fig. 248, J; fig. 253, ♀.

Polycentropus centralis Marshall and Larson, 1982: 24 , figs. 15–17, protibia, wings, mesonotum; fig. 47, J.

Polycentropus centralis Nimmo, 1986: 196 , figs. 127–130, J; figs. 131–132, ♀. Polycentropus centralis Armitage and Hamilton, 1990 : figs. A–D, J; fig. E ♀.

Polycentropus centralis Moulton and Stewart, 1996: fig. 538, wings; figs. 556, 564–565, J.

Polycentropus centralis Houghton, 2012 : fig. 266, J.

Diagnosis. Both sexes of this species are distinct and readily identifiable. Males of P. centralis can be distinguished from those of all other members of the P. confusus species group by the broad, stocky base of the inferior appendage. It can further be distinguished from males of all other species except P. pixi by the nearly straight phallus. From males of P. pixi , males of P. centralis additionally differ in the triangular head of the basodorsal process of the inferior appendage vs the rounded head seen in P. pixi .

Females of P. centralis are distinguished from those of all other members of the P. confusus species group by the smooth, lanceolate internal parts of gonopods VIII in ventral view and the ventral plates which are of uniform depth for ¾ length, beyond which they taper abruptly to a round apex in lateral view.

Adult description

General. Length of male 5.3–7.1 mm (mean = 6.6 mm; n = 5). Length of female 6.1– 8.9 mm (mean = 7.2 mm; n = 5).

Male genitalia ( Figure 13A–G ). 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 subtriangular in some specimens. Intermediate appendages originating beneath terga IX+X and extending beyond them, oriented subtly ventrad, their apices each bearing 5 small setae; in dorsal view apices proximate, subparallel. Bodies of pre-anal appendages each emarginate dorsally, produced porsterad in subtriangular process with additional round posteroventral process, or rarely round, produced, lacking round posteroventral process; dorsal process long, curved ventrad, extending above head of basodorsal process of corresponding inferior appendage, acute apically; in dorsal view slender, elongate, nearly straight to curved subtly laterad until mid-length, curved slightly mesad beyond mid-length. Inferior appendages in lateral view each with broad stocky base, capitate basodorsal process erect with narrow neck and triangular head round dorsally and projecting ventrad with its pointed apex visible above main body of appendage, main body of appendage nearly straight, with stocky base, dorsal margin curved strongly ventrad to about mid-length, ventral margin oriented slightly ventrad to about mid-length, with dorsal and ventral margins subparallel beyond mid-length to round apex extended posterad even with apices of intermediate appendages; in ventral view parallel, wide basally, distally tapering to round apex, lateral margins of basodorsal process usually visible beyond lateral margins of main body of inferior appendage, remainder of basodorsal process hidden, in cleared specimen broad, with medial pointed projection; in caudal view oblong, with medial projection round, typically oriented slightly mesoventrad and short, broad, rarely oriented strongly mesoventrad and narrow, elongate. Phallus a fully sclerotised tube, in lateral view with larger base, nearly straight along length, apical section subrectangular, internal spinules absent, internal phallic sclerite long, horizontal, with narrow, round ventral base broadening to subtrapezoidal posterior vertex.

Female genitalia ( Figure 14A–B ). Venter VIII in ventral view with ventral plates convergent, wide, subovate, tapering basally, covered with setae; in lateral view each broad basally with dorsal and ventral margins parallel for ¾ length, tapering abruptly in final ¼ length, terminating in narrow, round posterior apex; posterior apex of external parts of gonopods VIII in ventral view with posterior margin subtriangular and round mesally; in lateral view extending beyond ventral plates in evenly tapered process with round apex oriented posterodorsad; internal parts of gonopods VIII in ventral view visible through venter VIII even in uncleared specimen, appearing smooth, darker than surrounding tissue, subparallel, lanceolate, with tapered, acute posterior apices distinctly anterior of apices of ventral plates, anterior ends tapered, extending to sclerotised external part of gonopods VIII at basal fourth of ventral plates; in ventral view anterior part of genital chamber stocky, sclerotised, semi-circular, wrapping around posterior apex of processus spermathecae, posterior margin appearing cushioned; processus spermathecae subovoid, appearing flat, bearing opening of ductus spermathecae.

Larva. Described by Ross (1944). Redescribed by Orfinger et al. (2023).

Pupa. Unknown.

Notes. Males of P. centralis exhibit some variation across the species̍ wide range. Of note, a form with a subtriangular posterior margin of sternum IX and rounded, less produced bodies of the pre-anal appendages is seen in specimens collected from LaSalle County, Illinois.

Biology. Adults of P. centralis have been collected from May to October while late-instar larvae have been collected from March to May. This species occurs in fast-flowing, low-order streams with various substrates. This species seems to be more common in the western portion of its range; it is the most commonly collected Polycentropus species in the interior highlands and is sometimes collected in abundance ( Moulton and Stewart 1996; present study).

Distribution ( Figure 41 ). Canada: Newfoundland and Labrador, Nova Scotia, Ontario; USA: Alabama, Arkansas, Illinois, Indiana, Iowa, Kansas, Kentucky, Michigan, Minnesota, Missouri, Mississippi, New York, Ohio, Oklahoma, Pennsylvania, Tennessee, Texas, Virginia, West Virginia, Wisconsin.

This is a widespread species with few gaps in its known distribution. Of note, this species has been recorded in Newfoundland and Labrador ( Marshall and Larson 1982; Nimmo 1986) and Nova Scotia ( Nimmo 1986) but has not been reported from nearby states and provinces such as Maine, Quebec, and New Brunswick. It is possible that these far north-eastern records represent relict populations or alternatively that the species exists in nearby areas such as Maine, Quebec, and New Brunswick but has yet to be recorded. Given that P. centralis has been recorded from Wisconsin, Indiana, Ohio, and Ontario, it may also occur in Michigan. Similarly, P. centralis is known from Texas, Arkansas, and Mississippi, but has yet to be recorded from Louisiana and could well be taken from northern Louisiana in the future.

Material examined. Holotype: USA. Missouri: St. Louis County, W. St. Louis , Aug. Busch coll., vi-1904, 1 male ( MCZ Entomology 11,549) . Allotype: USA. Illinois: Union County, Wolf Lake , Hutchins Creek, [N37°30 ʹ 40.86″, W89°22 ʹ 38.7480″], B.D. Burks coll., 31-v-1940, 1 female ( INHS Insect Collection 37,246) .

Non-type material. USA. Alabama: Franklin County, Dismal Branch at Falls in Dismal Wonders Garden , UV light, S .C . Harris coll ., 29-v-1983, 4 females ( FAMU) . Lauderdale County, Cypress Creek at County Highway 85, 18-vi-1983, 1 male ( FAMU) . Marion County, North Fork Creek at Highway 17, LT and S .C . Harris coll ., 24-vi-1983, 1 male ( FAMU) . Arkansas: Johnson County, Mulberry River , UV light, D .E . Bowles coll ., 22-ix -1985, 10 males, 2 females ( FSCA) . Newton County, David Creek at Mt . Hersey, [N36° 00 ʹ 36.39″, W97°57 ʹ 19.85″], 38- iii-2021, 11 larvae ( FAMU) . Illinois: LaSalle County, Wetlands South of Iron Bridge , Lone Star Zone, M .A . Repiscak coll ., 22-v-2021, 1 male ( INHS Insect Collection 932,315) . Pope County, Lusk Creek at Dog Hollow Creek , 6.4 km NNE Eddyville, T11 S R6 E S22 N-W1-4, Site L _03, UV light trap, [N37°32 ʹ 56.04″, W88°32 ʹ 29.76″], J .M. Turner and T . Heatherly coll ., 9-vii-2003, 109 males ( INHS Insect Collection 39,179) . Union County, La Rue, Running Lick Creek , [N37°32 ʹ 44.02″, W89°27 ʹ 12.99″], B .D. Burks, G. T. Riegel coll ., 12- v-1939, 1 larva ( INHS Trichoptera 53,462) . Wolf Lake, Hutchins Creek , [N37°30 ʹ 40.86″, W89° 22 ʹ 38.75″], Frison and Ross coll ., x-1939, 4 females ( INHS Trichoptera 48,571) . Kentucky: Marion County, Salt Lick Creek, J .K . Moulton and M .A. Floyd coll ., 28-v-2006, 3 male ( FAMU) . Oklahoma: Latimer County, UV light, K . Stephan coll ., vi-1989, 2 males, 1 female ( FSCA) .

Figures

Figure 13. Polycentropus centralis Banks, 1914, male genitalia (holotype and additional Illinois, USA material). A. left lateral (with phallus removed); B. variation of left lateral (with phallus removed). C. dorsal; D. segment IX and inferior appendages, ventral; E. phallus, left lateral; F. dorsobasal process of right inferior appendage, caudal; G. variation of dorsobasal process of right inferior appendage, caudal.

Figure 14. Polycentropus centralis Banks, 1914, female genitalia. A. left lateral; B. ventral.

Figure 41. Known Canadian province and US state distribution of Polycentropus centralis Banks, 1914, as indicated by grey shading.