Urochordeuma bumpusi Silvestri, 1909

Shear, William A. & Marek, Paul E., 2019, Urochordeumatidae Silvestri, 1909, a millipede family endemic to Washington State, USA (Chordeumatida, Striariidea, Striarioidea), Zootaxa 4657 (2), pp. 352-360 : 353-356

Urochordeuma bumpusi Silvestri, 1909

Figs 1–12

Urochordeuma bumpusi Silvestri 1909, p. 230 ; 1913, p. 305. Hoffman, 1999, p. 256.

Urochordeuma porona Chamberlin 1941, p. 23 . Shear, 1972, p. 260. Hoffman, 1999, p. 256. New subjective synonymy.

Material examined: Of U. bumpusi , male holotype from Longmire Springs, Pierce County, Washington, USA, deposited in the Museo Civico di Storia Naturale de Genova, Italy, examined by WAS January, 2019. Male holotype of U. porona from Snoqualmie Pass, King County, Washington, USA, deposited in the United States National Museum of Natural History, examined by WAS in 1970 ( Shear 1972).

Diagnosis (family, genus, species): Distinct from all other North American chordeumatidans in the broad (ca. 1/4 width of trunk ring), flat, polydesmid-like paranota ( Fig. 2 ) beginning on the third or fourth post-collum ring—not as in Rhiscosomididae with narrow paranota (ca. 1/6 width of ring). Male first legpair uniquely modified, with a long mesobasal process on the femur nearly three times as long as the femur itself ( Figs 1 , 5 ).

Etymology: Silvestri named the species to honor Hermon Carey Bumpus (1862–1943), who at the time was the Director of the American Museum of Natural History in New York. Bumpus had a distinguished career, heading the AMNH, the Marine Biological Laboratory, and the U.S. Bureau of Fisheries Laboratory (Woods Hole, Massachusetts). He later served as president of Tufts University (http://en.wikipedia.org/wiki/Hermon_Carey_Bumpus). Chamberlin did not explain his choice of a species name, and there is no Greek or Latin word porona . Chamberlin likely adapted the word from ancient Greek, póros, “passage” perhaps in reference to Snoqualmie Pass.

Description: Male from Horseshoe Lake, Pierce County, Washington.

Length about 15 mm, greatest width 2.7 mm.

Head densely setose. Subtriangular eyepatches with 14–16 ocelli, well pigmented. Labrum (lab, Fig. 1 ) strongly, broadly rebordered, with paired subacute nodules. Stipes of mandibles (ms, Fig. 1 ) with distal triangular process.

Collum as long as wide, extended ventrolaterally, highly arched. Ring 2 with small paranota, paranota increasing in size on more posterior rings, reaching maximum width by ring 7; strongly rebordered, rebordering extends across width of metazonite. Metazonites set with many small tubercles, each bearing two acute projections, somewhat obscured by cerotegument. Metazonites posteriorly with four low, rounded bumps more prominent on midbody to posterior rings. Arrangement of metazonital setae unique: lateralmost seta in notch on paranotal margin, paralateral seta a short distance mesad, mesal seta much more anterior, near median sulcus.

Epiproct shallowly trilobed (t, Fig. 3 ), spinnerets directed anteriorly.

First sternum broad (st1, Fig. 1 ), greatly expanded.

First legpair (L1, Fig. 1 ; Fig. 5 ) with six podomeres (lacking trochanter), as long as subsequent legpairs, femora with long basomesal processes (fp1, Fig. 1 : Fig. 5 ) three times the length of the femora proper, tapering to blunt tip; anteriodistal surface of femur with many small teeth. Second legpair (L2, Fig. 1 ) unmodified but with prominent spermatic processes. Third legpair (L3, Fig. 1 ; Fig. 6 ) coxae (cx3, Fig. 1 ; Fig. 6 ) extended as long lobes nearly as long as legs themselves, finely toothed on anterodistal surface; femora distally inflated. Fourth sternum bearing anterior knob (s4, Fig. 1 ) projecting between coxae of legpair three. Prefemora of legpair four (L4, Fig. 1 ) distally inflated. Legpairs five and six unmodified. Legpair seven with lamellate coxal lobes.

Gonopod sternum ( Fig. 7 ) large, complete, spiracles slitlike, possibly vestigial. Gonopod coxae basally fused, with anterior groups of setae. Gonopods with two distinct processes, each divided, tips projecting anteriorly ( Figs 7– 9 ). Anterior process with lateral acuminate tip, mesal part broader, with appressed fimbria. Posterior process anterior tip with ventral ridge finely fimbriate, terminating in four small, subtriangular teeth; posterior tip deeply divided into many highly branched, finely acute processes. Ninth legpair ( Fig. 10 ) reduced to coxae and single telopodite articles; coxae bearing prominent terminal hooks anteriorly directed. Telopodite articles densely setose mesally, lateral surfaces granular, with small, nipple-like projections. Coxae of legpair 10 with small glands, otherwise not modified.

Female similar to male but lacking secondary sexual modification of anterior legs. Collum significantly smaller than in male, slightly longer than wide, not strongly arched or extended ventrolaterally. Vulvae as in Fig. 11 .

New Records: See Fig. 12 for the complete distribution as presently understood, including the two type localities. Unless noted, all collections by Rod Crawford and all material deposited in the University of Washington Burke Museum. WASHINGTON: King Co.: Bridle Trails State Park, from maple leaf litter, 500’ (152.4m) asl, 47.653°N, 122.173°W, 16 March 1985, m; Southeast of Black Diamond , from mixed leaf litter, 720’ (219.5m) asl, 47.291°N, 121.985°W, 1 November 2006 , m; Snoqualmie , 47.5°N, 121.8°W, 22 February 1940 , N. Kobylk, m, Twin Falls / Iron Horse trailhead, 47.4442°N, 121.6680°N, 25 February 2004 , W. Leonard , C. Richart, ff; Schmitz Park, from maple litter, 150’ (46.72m) asl, 47.574°N, 122.398°W, 13 October 1985 , m, f; North Bend , 440–460’ (134.1 to 140.2m) asl, 47.49°N, 121.78°W, 21 April 1896, T . Kincaid ; Pratt Lake Trailhead, N of I-90, 47.3972°N, 121.4852°S, W. Leonard, 25 October 2003 , juvs; Tinken Road exit, north side of I-90, Snoqualmie National Forest, 1750’ asl, 47.3973°N, 121.4853°W, 7 June 2006 . W. Leonard , juvenile. Pierce Co.: North of Little Mashel River, under cut wood, 2200’ (670.6m) asl, 46.817°N, 122.151°W, 12 July 1980 , m; Horseshoe Lake , from leaf litter, 750’ (228.6m) asl, 46.915°N, 122.271°W, 4 September 1977 , A. Ruggles , m, f; Lonesome Lake, from dead wood fragments in forest, 4800’ (1463m) asl, 47.008°N, 121.662°W, 23 July 2010 , m, f. Thurston Co.: Hospital Creek , 5 mi S, 3 mi E of Vail, 12 October 2003 , W.Leonard, juvs. Whatcom Co.: Sumas Mountain , from maple leaf litter, 700’ (213.4m) asl, 48.934°N, 122.155°W, 11 October 1986 , m.

Notes: The differences cited by Chamberlin in describing U. porona are not consistent when more specimens from multiple localities are examined. The maximum width of all mature specimens studied here ranged from 2.6 to 3.1 mm, and the proportions of the collum (of males) were similar in all. However, the collum is sexually dimorphic in the species, and is larger and more highly arched in males to accommodate the greatly enlarged sternum of the first legpair. This creates a commodious space ( Fig. 1 ) defined laterally by the femoral processes of the first legs and the coxal processes of the third legs; we speculate that this space and the first and third leg modifications are adaptations to firmly hold the female’s head during mating. Silvestri had both sexes available for study, while Chamberlin had only a single male, which may explain his statement regarding the length of the collum; but this highly three-dimensional structure can appear differently depending on viewing angle. Shear’s (1972, fig. 446) illustration misplaces the paralateral setae, but Silvestri (1913) illustrated them correctly. The setae have been rubbed off the specimen used for Fig. 2 and the sockets are obscured by cerotegument (ct, Fig. 1 ). While many specimens have a definite cerotegument, some males do not—possibly they have recently molted.

Silvestri (1913) and Shear (1972, fig. 447) show a single flagellocoxite, probably sheathed by the anterior angiocoxite process. While present, the flagellocoxite was not visible in our SEM preparations.

From label data, it appears that U. bumpusi is most often associated with deciduous leaf litter, particularly from maple. Elevations of collecting sites range from 150’ to 4800’ (45.7 m to 1463 m) asl, a broad range given the northerly latitude. The species is not common; collections mostly consist of single specimens or no more than three specimens, while collections of other chordeumatidans from the same localities may include 10– 20 specimens. The Whatcom County collection is a considerable extension, being some 116 miles (187 km) north-northwest of Snoqualmie Pass, the previous most northerly locality, and suggests that U. bumpusi will be found in intervening locations and perhaps northward into British Colombia, Canada. Longmire Springs, the type locality for U. bumpusi , was a long-popular hot springs resort not far from Tacoma, Washington, at the time of Silvestri’s visit. It was later incorporated into Mount Rainier National Park and is now an entry station into the park. Snoqualmie Pass, type locality for U. porona , is a large pass through the Cascade Mountains where Interstate 90 uses this geographical gap as the only four-lane east-west route across Washington State.

Figures

FIGURE 1. Head and first four rings of Urochordeuma bumpusi Silvestri, 1909, male, ventral view. Abbreviations: Lab, labrum; ms, mandibular stipes; st1, sternum of first legpair; L1–L4, legpairs 1–4 respectively; fp1, femoral process of first leg; cx3, coxa of third leg; s4, sternal knob of legpair 4; ct, fragments of cerotegument pulled loose from cuticle. First legs shaded red, second legs yellow, third legs green and fourth legs blue.

FIGURES 2–4. Urochordeuma bumpusi Silvestri, 1909. 2: Rings 10–12 (10, 11, 12) of male. 3: Rings 28, 29 and telson (28, 29, t) of male. 4: Small cuticular nodules of metazonite, each with two acute, posteriorly pointing processes.

FIGURES 5, 6. Urochordeuma bumpusi Silvestri, 1909. 5: First legpair, posterior view. 6: Third legpair, posterior view.

FIGURES 7–11. Urochordeuma bumpusi. 7: Gonopods, anterior view. 8: Left gonopod, mesal view. 9: Tip of right gonopod, lateral view. 10: Ninth legpair, anterior view. 11: Left vulva, ventral view. Abbreviations: acp, anterior coxal process; cx, coxa; cx9, coxa, cp9, coxal process, pcp, posterior coxal process; st, sternum; t9, telopodite

FIGURES 12. Northwest Washington, showing records of Urochordeuma bumpusi. Circles, new records. Triangle, type locality of U. bumpusi. Square, type locality of U. porona.