Retrorsia leonardi, Shelley, 2003

Shelley, Rowland M., 2003, A new polydesmid milliped genus and two new species from Oregon and Washington, U. S. A., with a review of Bidentogon Buckett and Gardner, 1968, and a summary of the family in Western North America (Polydesmida: Polydesmidae), Zootaxa 296 (1), pp. 1-12 : 5-9

Retrorsia leonardi , new species

Figs. 3–4

Type specimens. Male holotype ( NCSM) collected by W. P. Leonard on 14 December 2002 at Ainsworth State Park in the Columbia River Gorge National Scenic Area , ca. 30 mi (48 km) E of downtown Portland , Multnomah County, Oregon . Male paratype ( CAS) collected by D. R. Malcolm on 21 January 1968 along Bishop Road, 2 mi (3.2 km) N Helvetia [ca. 8 mi {12.8 km} NW Portland], Washington County, Oregon . Six male and 4 female paratypes ( CAS, NCSM, VMNH) collected by E. Benedict on 8 January 1972, 3 mi (4.8 km) SW Clatskanie , Columbia County, Oregon .

Diagnosis. Stem of gonopodal telopodite long, slender, and curvilinear, widening slightly distad at level of endomerite but not produced into a discrete flange; pulvillus rounded; tibiotarsus bent strongly dorsad, apically broad; endomerite short and subtriangular, oriented transversely to telopodal stem.

Holotype. Head densely covered with short, fine, parallel­sided setae; epicranial suture distinct; genae not extending beyond adjacent cranial margins. Paranota broad with strongly serrate, notched margins on segments 1–6, becoming slightly narrower on segment 7 and progressively less dentate caudad. Epiproct short and broad, with two tufts of long, terminal setae. Paraprocts with slight marginal rims.

Gonopodal aperture obchordate, caudal margin extending backwards between 9th legs, sides flush with metazonal surface. Gonopods in situ with telopodites extending anteriad in subparallel arrangement over anterior margin of aperture and sternum of segment 6. Gonopod structure as follows ( Figs. 3–4 ): Coxa large, expanding into ventral lobe extending for 1/4 of length of telopodite. Prefemur expanding distad into short, rounded lobe. Telopodite relatively narrow, curving gently ventrad for most of length, distal expansion short and narrow, pulvillus small and rounded, widely separated from expansion, hairs continuing distad along ridge on medial margin; tibiotarsus curving strongly dorsad, directed caudad, folded distad, apically broad; endomerite short and subtriangular, oriented transversely across stem, expanding into two narrowly rounded lobes. Prostatic groove apparently without loop or chamber, opening on medial surface proximal to pulvillus.

Male paratypes. Agreeing closely with holotype in all details.

Ecology. The holotype was collected on a north­facing slope, probably in sword fern litter ( Polystichum munitum ); the paratype from Washington County was extracted from a berlesate of mixed conifer and deciduous duff. Their discoveries in winter along with several new chordeumatidans ( Shear & Leonard, 2003) testifies to the need for collecting during cool weather in the Pacific northwest .

Distribution. Occurring along a 70 mi (112 km) stretch in the lower Columbia River Valley, Oregon, from the Gorge in Multnomah County westward to Columbia County some 30 mi (48 km) from the river’s mouth.

Etymology. I am pleased to name this species for the collector, William P. Leonard, in recognition of his discoveries of new milliped species and genera in the northwestern United States.

Remarks. The gonopod is so minute that even after clearing in lactic acid for a few days and viewing at 400x under a compound microscope, I could not discern whether or not there is a distal loop or chamber on the prostatic groove.

Retrorsia benedictae , new species

Figs. 5­8

Type specimens. Male holotype ( CAS) and 3 male and 1 female paratypes ( CAS, NCSM) collected by E. M. Benedict on 27 November 1971 along OR hwy. 202, 3 mi (4.8 km) SE Olney, Clatsop County, Oregon. Male paratype ( CAS) taken by same collector on same date 6 mi (9.6 km) SE Olney and the North Fork Klaskanne River , Clatsop County .

Diagnosis. Stem of gonopodal telopodite relatively broad, curving moderately ventrad, with distinct flange distad at level of endomerite; pulvillus oblong; tibiotarsus curving gently dorsad, apically acuminate; endomerite relatively long, breadth and configuration variable, oriented along axis of telopodal stem.

Holotype. Somatic features as in R. leonardi except paranotal margins lightly dentate on segments 1–6, becoming slightly narrower on segment 7 and progressively less dentate caudad. Epiproct with two pairs of relatively short terminal setae.

Gonopodal aperture rounded, caudal margin not extending backwards between 9th legs. Gonopods in situ extending ventrad in aperture in subparallel arrangement, not extending over anterior margin of aperture or sternum of segment 6. Gonopod structure as follows ( Figs. 5–6 ): Coxa large, with horizontal, triangular projection directed ventrad, without ventral lobe. Prefemur with margin gently sinusoid, without ventral lobe. Telopodite relatively broad, curving moderately ventrad for most of length, distal expansion in form of discrete concave flange with subacuminate corners, demarcated from tibiotarsus by strong indentation, pulvillus oblong, expanding apically, arising at base of flange; tibiotarsus curving gently dorsad, proximal corner slightly expanded, apically linear and acuminate; endomerite long, apically acuminate, oriented along axis of telopodal stem, curving generally subparallel to tibiotarsus but shorter than latter, with short, triangular, medial and lateral lobes, former overlapping telopodal stem at level of base of tibiotarsus. Prostatic groove with distinct distal chamber.

Male paratypes. Agreeing closely with holotype in all particulars.

Variation. The gonopods of the Washington specimen ( Figs. 7–8 ) differ from those of the Oregon males in that the flange is less concave and has a sublinear margin, the pulvillus is apically rounded and not expanded, and the proximal corner of the tibiotarsus is pointed but not produced into a lobe. The most variable aspect is the endomerite, which is blade­like and broader than that of the holotype. It also lies parallel to the telopodal stem instead of the tibiotarsus and expands apically into two lobes that are similar to those in R. leonardi , though the terminal one is slightly produced and the proximomedial lobe is absent .

Ecology. The holotype and associated paratypes were collected at ca. 400 ft. (120 m) elevation, and the other paratype was at 800 ft. (240 m); no habitat information is available for either site. The Washington individual was encountered at 900 ft. (270 m) elevation on a gentle slope in the Willapa Hills on Washington State Forest lands. The habitat is a young, mixed coastal forest of Douglas­fir ( Pseudotsuga menziesii ) and western hemlock ( Tsuga heterophylla ). Mature trees have been harvested twice on this site, so this is a “third growth” forest approximately 40 years old. Conifers dominate but are mixed with red alder ( Alnus rubra ) and other hardwoods; the understory vegetation is sparse, consisting primarily of ferns and shrubs.

Distribution. Occurring near the mouth of the Columbia River in northeastern Oregon and some 25 mi (40 km) to the north in coastal Washington ( Fig. 2 ); the area is about 25 mi (40 km) west of that of R. leonardi . In addition to the types, the following sample is available:

WASHINGTON: Pacific Co., 2 mi (3.2 km) NW Menlow, ♂, 17 December 2002, J. Ziegltrum, R. Shoals ( CAS) .

Etymology. This species is named for the collector of the holotype and paratypes, Ellen M. Benedict, in recognition of her efforts in collecting minute litter organisms in Oregon.

Figures

FIGURE 2. Distribution of Retrorsia; dots, R. leonardi; triangles, R. benedictae. OR, Oregon; WA, Washington.

FIGURES 3–4. Retrorsia leonardi. 3, right gonopod of holotype, medial view (drawn at 200x magnification). 4, telopodite of the same, lateral view (drawn at 400x magnification). C, coxa; E, endomerite; P, pulvillus; PF, prefemur; T, telopodite; TT, tibiotarsus.

FIGURES 5–8. Retrorsia benedictae (all drawn at 400x magnification) 5, telopodite of left gonopod of holotype, medial view. 6, the same, lateral view. 7, telopodite of left gonopod of male from Pacific County, Washington, medial view. 8, the same, lateral view. F, tibiotarsal flange; other abbreviations as in figs. 3–4.