Pseudopolydesmus erasus, ERASUS (LOOMIS, 1943)

Sierwald, Petra, Hennen, Derek A, Zahnle, Xavier J, Ware, Stephanie & Marek, Paul E, 2019, Taxonomic synthesis of the eastern North American millipede genus Pseudopolydesmus (Diplopoda: Polydesmida: Polydesmidae), utilizing high-detail ultraviolet fluorescence imaging, Zoological Journal of the Linnean Society 187 (1), pp. 117-142 : 125-127

PSEUDOPOLYDESMUS ERASUS ( LOOMIS, 1943)

( FIGS 9–12 )

Polydesmus erasus Loomis, 1943: 406 , fig. 17, pl. 1: fig. 5, ♂ HT (MCZ, non vidi).

Dixidesmus erasus – Chamberlin, 1943c: 18. – Causey, 1952: 7 (= D. humilidens ). – Chamberlin & Hoffman, 1958: 66.

Pseudopolydesmus erasus – [ Withrow, 1988: 84, figs 19, 84, 88, 92, 108, 113, 122–126, map 5, tables 9–11.] – Hoffman, 1999: 444 (= D. tallulanus ; D. penicillus ).

Dixidesmus tallulanus Chamberlin, 1943c: 19 , fig. 34, ♂ HT (USNM, vidi). – Chamberlin & Hoffman, 1958: 67.

[ Pseudopolydesmus tallulanus – Withrow, 1988: 79, figs 75, 83, 87, 91, 107, 112, 122–128, map 5, tables 9–11.]

in Ps. serratus . Leading and distal margins moderately curved, similar to Ps. serratus but less curved than Ps. canadensis and Ps. collinus . Denticles weak to obliterated. Trailing margin only slightly concave, nearly straight. Anterior blister row medially much thicker than median blister row, narrowing laterally to become much narrower than median blister row. Median blister 2 much larger in area than MB1. Median blister row thicker than posterior blister row. Central paranotal blisters occupying medial two-thirds of paranota. Lateral blisters anteriorly extending mediad.

Dixidesmus penicillus Chamberlin, 1943c: 19 , fig. 35, ♂ / ♀ ST (USNM, vidi). – Chamberlin & Hoffman, 1958: 67.

Dixidesmus humilidens Chamberlin, 1943c: 20 , fig. 36, ♂ / ♀ ST (USNM, vidi).

Diagnosis

Size: Large to medium-large, with length ranging from 15.8 to 31.8 mm and an average body length of 21.4 mm (N = 143; Withrow, 1988: 83, 88, 199). Size variable, comparable to Ps. canadensis , Ps. collinus and Ps. serratus . Usually larger than Ps. pinetorum .

Paranota and tergal sculpture ( Fig. 9 ): Corners of paranota forming a trapezoid, with the anterior (AMC to ALC) edge longer than the posterior (PMC to PLC) edge. Ratio of anterior to posterior edge length smaller than Gonopod ( Figs 10–12 ): Gonocoxa ventral lobe with single gonocoxal plate. Telopodite basally curved, moreor-less straight between pulvillus and process m4, terminally curved, basal half of acropodite distinctly thickened. Pulvillus large and pointed, midway between base and terminus of acropodite. Process m3 absent. Process e1 elongate and straight, arising from thickened area; e2 large and recurved, originating close to base of e3; e3 subtriangular, varies from large to miniscule; e4 nearly identical to m 4 in size and shape ( Figs 10A , 11A , 12A ). Process m1 conspicuous, medial of pulvillus; m2 large, subtriangular; m4 typically shaped, well separated from larger m2 ( Figs 10B , 11B , 12B ).

Type notes

Polydesmus erasus (♂ HT and three ♀ PT, MCZ, non vidi): From Monte Sano State Park , Madison Co., AL, USA, collected 22 July 1939 . According to the description by Loomis (1943), the e3 process is completely absent in Ps. erasus . No such specimen has been seen by the authors; it is more likely that Loomis overlooked the process or his specimen was damaged.

Dixidesmus tallulanus (♂ HT and one ♂ PT, USNM, vidi): ♂ HT from between Clayton and Tallulah Falls, Rabun Co., GA, USA, collected 28 April 1943 ; ♂ PT from Tallulah Falls , Habersham Co., GA, USA, collected 27 April 1943; both collected by W. Ivie . We found two type lots. Type lot 1: labelled ‘HT’, contains one fragmented male, with dissected gonopods in genitalia vial. Type lot 2: labelled ‘PT’, contains one intact male.

Dixidesmus penicillus (11 ♂ and five ♀ ST, USNM, vidi): Chamberlin (1943c) described an unspecified number of male and female specimens from north and northwest of Clarkesville, Habersham Co., GA, USA, collected 27 April 1943 by W. Ivie . We found two type lots. Type lot 1: labelled ‘Types’, contains two intact males, two fragmented females, and two small vials; first small vial labelled ‘HT’ (by Withrow?), contains fragmented male, with dissected gonopods in genitalia vial; second small vial labelled ‘Lectoallotype’ (by Withrow?), contains fragmented female. Type lot 2: labelled ‘Paratypes’, contains two females and eight males, some males with gonopods damaged.

Dixidesmus humilidens (two ♂ and two ♀ ST, USNM, vidi): From Gainesville, Hall Co., GA, USA collected 24 April 1943 by W. Ivie . Type lot labelled ‘ erasus ’ by Withrow. Contains one female, one fragment and two small vials; first small vial labelled ‘Holotype’ by Withrow, contains fragmented male, with dissected gonopods in genitalia vial; second small vial labelled ‘Lectoallotype’ by Withrow, contains intact female with everted vulvae.

Distribution

Southern Appalachian Mountains, west through Tennessee and Kentucky into southern Illinois and south through Alabama to the coast of the Gulf of Mexico.

Additional specimens examined

FMNH INS 1554, 1556 , 3120684 , 3120685 * .

Figures

Figure 9. Pseudopolydesmus erasus, metatergite and paranota of body ring 9. Adult male (FMNH INS3120685, ultraviolet enhancement).

Figure 10. Gonopod of Pseudopolydesmus erasus (FMNH INS3120685). A, right gonopod, ectal view. B, left gonopod, medial view (image mirrored to match right gonopod).

Figure 11. Gonopod of Pseudopolydesmus erasus (FMNH INS3120685, ultraviolet enhancement). A, right gonopod, ectal view. B, left gonopod, medial view (image mirrored to match right gonopod).

Figure 12. Gonopod of Pseudopolydesmus erasus (FMNH INS3120685, scanning electron micrograph). A, right gonopod, ectal view. B, right gonopod, medial view.