Vasingtona irritans ( Chamberlin, 1910 )

Vasingtona irritans ( Chamberlin, 1910) View in CoL

( Fig. 1–12 View Figures 1–6 View Figures 7–12 )

Caseya irritans Chamberlin 1910: 241 View in CoL .

Vasingtona fasciata Chamberlin 1941a: 22 View in CoL . Synonymized by Gardner and Shelley 1989: 188.

Vasingtona irritans View in CoL — Gardner and Shelley 1989: 188.

Descriptive notes. Vasingtona irritans View in CoL is the largest and most widespread of the caseyids of the Pacific States ( Underwoodia species are transcontinental but do not occur in the range of other caseyid genera). Specimens range from 16–22 mm in length, and the species occurs from the southwest corner of British Columbia to northwestern Oregon. At the time of the publication of the monograph by Gardner and Shelley (1989), this was the only species of ochrogrammatine known to span the Columbia River , but we show below that Ochrogramma bentona View in CoL has a very similar range. Relatively few records from Washington are cited in Gardner and Shelley (1989) but here we add many new ones showing that V. irritans View in CoL is quite common in Washington.

In addition to the mandibular flanges, the males of V. irritans exhibit a typical ochrogrammatine suite of secondary sexual modifications of the anterior legs, as described in the subfamily diagnosis, in addition to which the seventh legpair coxae have posteriorly projecting lobes (cx7, Fig. 3 View Figures 1–6 ).

The gonopods of V. irritans ( Fig. 4–8 View Figures 1–6 View Figures 7–12 ) superficially appear very complex, due in large part to the great elaboration of the highly branched arborescent processes characteristic of the subfamily. Gardner and Shelley (1989) applied a then-current terminology to the various parts of the gonopod that in our opinion conceals homologies with Ochrogramma gonopods and those of other caseyids and striarioids. We propose a more general terminology based on studies of the gonopods of many families and genera of chordeumatids ( Shear and Leonard 2007). In anterior view ( Fig. 4 View Figures 1–6 ) the gonopod sternum (s, Fig. 4 View Figures 1–6 ) can be seen to be divided in the midline by a suture spanned with a poorly sclerotized membrane. The bodies of the coxae (c, Fig. 4 View Figures 1–6 ) are reduced to curved, flattened plates from which arise the massive anterior angiocoxites (aac, Fig. 4 View Figures 1–6 ), their anterior surfaces completely covered with arborescent processes ( Fig. 7 View Figures 7–12 ); mesally the anterior angiocoxites are attenuated into long processes sharply curved at their tips. In lateral view ( Fig. 6 View Figures 1–6 ), the posterior angiocoxites (pac, Fig. 6 View Figures 1–6 ), likewise with many arborescent processes, arise basally. The poorly sclerotized colpocoxites collapse (cc, Fig. 5, 6 View Figures 1–6 ) during SEM preparation. In posterior view ( Fig. 5 View Figures 1–6 ), the large telopodites (t, Fig. 5, 6 View Figures 1–6 ) extend through roughly a right angle from their articulations with the coxae and there is a large, arborescent process a little below midway in their length. Because of their obvious articulation with the coxae, we consider these structures to be telopodites, but the presence of telopodites of the gonopods is otherwise rare among the Chordeumatida . A few very thin branches can be seen emerging near the curved tips of the anterior angiocoxites and these may represent flagella or flagellocoxites.

The arborescent processes ( Fig. 7, 8 View Figures 7–12 ) are complex. At high magnification ( Fig. 8 View Figures 7–12 ), the terminal branches or buds flare at their tips and seem to be membranous, somewhat like tiny suction cups. What function these processes serve remains obscure.

The ninth legs ( Fig. 9–11 View Figures 7–12 ) are typical of species of caseyids, with simple coxal processes (cp, Fig. 9, 10, 11 View Figures 7–12 ) and single, flattened, button-like telopodite articles (t9, Fig. 9–11 View Figures 7–12 ). Near the base of each coxal process is a small pore (p, Fig. 9, 11 View Figures 7–12 ), probably homologous to the much larger pores on the coxae of the tenth legpair. The telopodite article appears poorly sclerotized on its medial surface, where it is more densely setose ( Fig. 9 View Figures 7–12 ).

One small deficiency of the otherwise excellent monograph by Gardner and Shelley (1989) is their lack of descriptions and illustrations of the tenth legpair for many of the caseyid species they describe. As seen in our illustration ( Fig. 12 View Figures 7–12 ) the coxae of these legs are enlarged, quadrate and with broad openings of the coxal glands (cxg) on their anterior surfaces. The trochanters (tr10) appear to be at least partially fused to the coxae and bear two rounded processes mesally, a short proximal one and much longer distal one.

Not surprisingly for a millipede species that ranges broadly, Gardner and Shelley (1989) noted some variation in the gonopods, as did we. However, we concur that this variation is not of a nature that would suggest splitting up the species. Since V. irritans is common and easy to collect, future work on the phylogenomics of the species should resolve questions of the significance of this variation.

New records

OREGON: Columbia Co. : Keystone Creek , Clatskanie Valley , N40°04.933′, W123°09.411′, 132′ asl, 8 February 2004, W. Leonard, C. Richart, m, f. WASHINGTON: Cowlitz Co.: Germany Creek, 3.1 mi N on SR14, 11 November 2004, W. Leonard, ff GoogleMaps ; Germany Creek at end of county road, 5.5 mi N of Stella, N46°15.561′, W123°08.067′, 450′ asl, 22 November 2003, W. Leonard, C. Richart, mm GoogleMaps ; Pin Creek , Kool Road , 0.4 mi W of FishPond Road, N47°04.450′, W122°50.818′, 180′ asl, 25 January 2004, C. Richart, W. Leonard, ff. Grays Harbor Co.: Inner Creek at Quinalt Lake Loop Road, N47°30.15′, W 123°46.93′, 13 February 2005, W. Leonard, C. Richart, f GoogleMaps ; middle fork of Satsop River , 2.9 mi N of SR12, N47°01.98′, W123°31.55′, 31 December 2004, W. Leonard, ff GoogleMaps ; Canyon River , N47°18.210′, W123°30.512′, 11 October 2002, W. Leonard, m GoogleMaps ; N47°18.846, W123°32.474, 980′ asl, 13 October 2003, W. Leonard, m; 6 mi W, 1.25 mi N of Matlock , 17 January 2003, W. Leonard et al., mm, ff ; Middle Fork Satsop River , 3.2 mi N of Brady, 3 January 2003, W. Leonard, C. Richart, mm ; Wynochee River Road , 10 mi N of SR12, east bank of Wynochee River , 3 January 2003, W. Leonard, m. Jefferson Co.: 12 mi E of US 101 on road to Queets Campground , N47°36.386′, W124°02.488′, 5 March 2005, W. Leonard, C. Richart, m. Lewis Co.: FR#25 8.5 mi S of Randall, Gifford Pinchot National Forest, N46°26.456′, W121°59.796′, 1050′ asl, 6 December 2003, W.Leonard, C. Richart, mm, f GoogleMaps ; Stillman Basin , 1.8 mi on Weyerhauser 4000 from Dee Ell McDonald Road, N46°30.87′, W123°12.09′, 1004′ asl, 4 December 2004, W. Leonard, C. Richart, mm GoogleMaps ; Iron Creek Campground, 9.6 mi S of Randall on SR25, Gifford Pinchot National Forest, 950′ asl, 21 December 2003, W. Leonard, f ; Fisher Creek at Tilton Road, N46°35.96. W122°22.04′ 973′ asl, 21 September 2003, W. Leonard, m with spermatophore GoogleMaps ; 604 Roswell Road , Centralia, 5 January 2003, C. Richart, m ; 8.5 mi S of Randall on FS25, Gifford Pinchot National Forest , W46°26.489′, W121°59.890′, 21 December 2003, W. Leonard, m. Pacific Co.: 1.1 mi S of SR6 on Trap Creek Road /B-line, N46°32.591′, W123°36.908′, 19 November 2005, W. Leonard, C. Richart, m, f GoogleMaps ; Ellsworth Creek Preserve, N46°23.887, N123°53.391′, 50′ asl, 23 November 2003, W. Leonard and others, mm, ff ; The Nature Conservancy Preserve , 8 mi E, 5 mi N of Long Beach, 14 March 2003, W. Leonard et al, m. Thurston Co.: Ranier Road , 3.0 mi NW of Military Road , Fort Lewis Military Reservation, 29 November 2003, W. Leonard, m ; Capitol State Forest , unnamed tributary to Perry Creek, N47°01.573′, W123°04.154′, 950′ asl, 27 October 2003, W. Leonard, f GoogleMaps ; Skookumchuck River , 5 mi S, 3 mi E of Vail, 2 October 2003, W. Leonard, mm, ff ; McAllister Springs , N47°02.387, W122°43.722′ 60-123′ asl, 7 February 2004, W. Leonard, C. Richart, m, f GoogleMaps ; Hospital Creek , above confluence with Skoocumchuck River, N46°46.396′, W122°35.133′, 15 December 2003, W. Leonard, K. McAllister, ff GoogleMaps ; Evergreen State College , Olympia, 26 January 2003, W. Leonard, m. Wahakiakum Co.: SR4 at milepost 23.7, 19 September 2003, W. Leonard, f ; Swede Park , residence at 369 Loop Road, Grays River, N46°18.499′, W123°40.128′, 50′ asl, 14 January 2004, W. Leonard et al., f GoogleMaps .