Rhynchelmis (Sutroa) rostrata ( Eisen, 1888 )

Fend, Steven V. & Carter, James L., 2014, Rhynchelmis subgenus Sutroa Eisen new rank, with two new species from western North America (Annelida, Clitellata, Lumbriculidae), Zootaxa 3760 (2), pp. 180-210 : 184-186

Rhynchelmis (Sutroa) rostrata ( Eisen, 1888)

( Fig. 1 )

Sutroa rostrata Eisen, 1888: 1 –7, Figs 1 –14

Sutroa alpestris Eisen, 1892: 322 –331, Figs 1 –30

Sutroa alpestris Eisen: Beddard 1892 : 195–202, Figs 1–8

Rhynchelmis rostrata (Eisen) : Brinkhurst & Cook 1966: 8 –9, Figs 1 F, 4G, 5A; Cook 1971: 260, Figs 5.8 G–I, 5.9 F; Fend & Brinkhurst (2000): 28 –38, Figs 53–99

Material examined. From type locality or adjacent sites: CALIFORNIA, San Francisco Co.: northern arm of Mountain Lake, seep at north willow area, 18 Apr 2000, N37.789 °, W122.471 °, coll. S.V Fend and J. Laws. CASIZ 192761, 3 dissected worms. USNM 1230304, 3 dissected. Lobos Creek, 12 Jan 1997, CASIZ 192762, 1 whole mount and 4 dissected.

From the Klamath watershed: OREGON, Klamath Co.: worms immature, unmounted unless otherwise noted; collected by J.L. Carter unless otherwise noted. Sprague River, 23 Jun 2008 (11); 9 Aug 2010 (2); 26 Jul 2011 (6). Spring Creek near source, approx. N42.670 °, W121.886 °, 23 Jun 2008 (10; 5 mature, dissected); 26 May 2009 (22); 3 May 2010 (75; 10 mature); 9 Aug 2010 (32; 4 mature); 30 May 2011 (78; 15 mature); 26 Jul 2011 (61; 17 mature, 4 dissected). Established wetland at northern end of Upper Klamath Lake, 27 May 2009 (2); 28 Jul 2009 (1); 4 May 2010 (4; 1 partially mature). Reclaimed, flooded farmland at northern end of Upper Klamath Lake, 28 Jul 2009 (1); 9 Jun 2010 (12); 21 Jul 2010 (2); 10 Aug 2010 (1); 1 Sep 2010 (2); 27 Jul 2011 (2). Northern shore of Upper Klamath Lake, littoral habitat, 9 Jun 2009 (7); 1 Sep 2009 (4); 31 Aug 2010 (1); coll. J.L. Carter and S.V. Fend. Lower Williamson River, 1 Feb 2011, (8). Upper Williamson River, 5 Aug 1999, 1 partially-mature; coll. R.W Wisseman. Lost River at Keller Bridge, 7 Sep 1999, 1 mature; coll. R.W. Wisseman. Lost River at Harpold Dam, approx. N42.170 °, W121.454 °, 29 Sep 1999, 1 mature, several immature in alcohol; coll. R.W. Wisseman. Lake Co.: Sycan Marsh, seep near Long Creek, 23 Jun 2001, 4 mature, dissected; coll. S.V. Fend and W.C. Fields. Sycan Marsh, Coyote Spring, 22 Jun 2001, approx. N42.850 °, W121.160 °, several mature, 2 dissected; coll. S.V. Fend and W.C. Fields.

Descriptive notes and remarks. Topotypic material. Some of the California specimens were collected at what appears to have been the exact site of Eisen’s collection, a small, slowly-moving seep with emergent vegetation. The original collection locality in Mountain Lake was “on the north shore, just at the mouth of a small spring, … in the richest mud, between the roots of aquatic plants” ( Eisen 1888). Additional specimens were collected in a slow-moving section of Lobos Creek about 500 m from the type locality.

Despite some obvious errors and omissions in the original description (e.g., position of ovaries and vasa deferentia), the new California series clearly shows diagnostic characters given in that account, particularly the spermatheca ( Fig. 9 in Eisen 1888) and the very elongate atria. It also conforms to corrections and supplemental descriptions of R. rostrata by Eisen (1892), as well as those based on material from other localities ( Beddard 1892 [as alpestris ]; Brinkhurst & Cook 1966; Fend & Brinkhurst 2000). Diagnostic characters clearly visible in the series include (1) the single, median spermatheca with several tubular diverticula joining the ectal duct ( Fig. 1 A), (2) the medially shifted penial bulbs with conical penes ( Fig. 1 B), (3) very elongate-tubular atria having a thick muscle layer in about the ectal half, and dense prostate layer entally, and (4) anterior vasa deferentia non-functional and thinner than the posterior pair. In the new material, the spermathecal diverticula range from 6 to 9, and are mostly unbranched. The spermathecae thus resemble populations deemed “typical” by Fend and Brinkhurst (2000, Fig. 55a–b), as opposed to the more highly branched diverticula of specimens from the R. alpestris type locality ( Fig. 7 in Eisen 1892; Fig. 55c in Fend & Brinkhurst 2000). Beddard’s R. alpestris redescription does not mention this detail, possibly because of reliance on sectioned material ( Fig. 5 in Beddard 1892). In three specimens, 1–2 diverticula extend into the postseptal cell mass on 8/9, confirming that it is sac-like (as proposed by Beddard 1892), rather than an “albumen gland” ( Eisen 1892). Atria extend to XIX–XXIV in mated worms, which is farther than in other R. ( Sutroa ) species, but typical for R. rostrata ( Fend & Brinkhurst 2000, Table 1); total atrium length is 5.8–8.6 mm. The few complete specimens have 116 to about 160 segments, body length 32–60 mm, and diameter in X 1.2–1.7 mm before slide mounting.

Upper Klamath Lake watershed. Rhynchelmis specimens from the Upper Klamath Lake watershed were examined to confirm that R. klamathensis n. sp. is not a lacustrine form of a widespread species. Although most Upper Klamath Lake Rhynchelmis collections were attributed to R. klamathensis (see below), nearly all Rhynchelmis specimens from sites other than open-water lake habitats had a distinct proboscis ( Fig. 1 C) and a limited number of body segments, so even immature specimens could be confidently distinguished from the lacustrine R. klamathensis . It seems likely that all of this material belongs to R. rostrata . Mature Klamath Basin R. rostrata were morphologically similar to material from other localities. The number of segments in mature worms was 83–149, fragmentation was uncommon, total body length was 34–58 mm, and diameter in X 0.9–1.5 mm. These values are comparable to those in Table 1 of Fend and Brinkhurst (2000) for typical R. rostrata from western North America. All of the dissected, mature R. rostrata from the Klamath Basin had an unpaired median spermatheca with several diverticula and a broad ampulla, distinguishing them not only from R. klamathensis , but also from a R. yakimorum variant described from springs on the downstream Klamath River ( Fend & Brinkhurst 2000). Retracted penial structures (bulbs) were similar in size (275– 460 Μm high) to those of R. klamathensis , although they appeared larger relative to the diameter of the worm; when extended, they appeared much larger, and were similar to those illustrated for other R. rostrata (compare Fig. 1 C with 2D, and with Fig. 52b in Fend & Brinkhurst 2000). Atria of all dissected R. rostrata were relatively straight, extending through many segments to XXII–XXVI, in contrast to the convoluted atria of most R. klamathensis specimens. Partially mature worms had a single, median spermathecal pore and male pores inside the chaetal lines. Rhynchelmis rostrata occurred with R. klamathensis at a littoral site near the confluence with the Williamson River; also at one reclaimed farmland site within the Williamson delta in September 2010.

Figures

FIGURE 1. R. rostrata from the type locality, Mountain Lake, San Francisco (A – B) and from Sycan Marsh, Klamath watershed (C). A. spermatheca. B. Ectal end of male duct, showing the conical penis retracted within bulb, ectal part of the atrium with thick muscle layer, and the vasa deferentia. C. Anterior end of a whole worm, with everted penes. Scale bars (A – B) 400 Μm, (C) 2 mm.

FIGURE 9. R. diespluviae n. sp. from Rainy Day Creek, reproductive structures; sagittal sections (A – B), transverse sections (C – I). A. Spermatheca. B. Detail of spermathecal bulb with very short duct at top. C. Spermathecal diverticulum. D. Spermathecal ampulla. E. Penial sac and base of penis, containing end of atrial duct. F. Penial sac and tip of penis. G – I. Atrium and vasa deferentia: near the ectal end, in XI (G); near the transition to the prostate-covered section (H); and in the ental, prostate-covered section, with 1 vas deferens embedded in the atrial muscle (I). Scale bars (A, C) 200 Μm, (B, D – I) 100 Μm.

FIGURE 7. R. diespluviae n. sp. from Rainy Day Creek, Idaho, reproductive structures. A. Atrium and vasa deferentia, sagittal view from a dissected worm (X – XVII, facing left). B. Spermathecae in VIII, reconstructed from transverse sections (arrows indicate positions of chaetae). C. Penial structures in X, reconstructed from transverse sections. Scale bar (B – C) 400 Μm.

FIGURE 5. R. klamathensis n. sp. from Upper Klamath Lake, reproductive organs; sagittal sections (A – D, F), transverse sections (E, G – I). A. Spermathecal bulb, duct, and ampulla joining the gut. B. Spermathecal bulb and duct, with part of a diverticulum. C. Penial bulb and sac, with a retracted penis. D – E. Partially retracted penes, within penial bulbs. F. Atrium, vas deferens and posterior male funnel at 10 / 11. G. Ectal part of atrium in X, with vasa deferentia free in sperm sac. H. Ental part of atrium with vasa deferentia free within prostate layer; the small, anterior vas deferens approaching the atrium. I. Atrium near the ental end; the posterior vas deferens is approaching the atrium. Scale bars (A – F) 200 Μm, (G – I) 100 Μm.