Leonardesmus injucundus, Shelley & Shear, 2006

Shelley, Rowland M. & Shear, William A., 2006, Leonardesmus injucundus, n. gen., n. sp., an aromatic, small-bodied milliped from Washington State, U. S. A., and a revised account of the family Nearctodesmidae (Polydesmida), Zootaxa 1176 (1), pp. 1-16 : 6-14

Leonardesmus injucundus , new species

Figs. 1 , 4–12

Type specimens. Four m, 23f, and 12 juvenile (4m, 8f) syntypes ( NCSM, FMNH, FSCA, CAS) collected by WPL on the following dates at the following two localities in eastern Grays Harbor Co., Washington (segment numbers, including epiprocts, are provided in parentheses for juvs.): ca. 15 mi (24 km) NE Aberdeen, along west bank of Middle Fork Satsop R., 3 mi (4.8 km) N US hwy. 12, N47°2.18' N, W123°31.81', 70' (22 m) asl, 1m, 11f, 26 November 2004 ( NCSM) , 4f, 3 juv. f (1 with 19 segs., 2 with 17 segs.), 31 December 2004 ( NCSM) , m(parts used for SEM), 2f, juv. f(19 segs.), 13 March 2005 ( FMNH) , and 2m (parts used for SEM) , 3f, 2 juv. f (17 & 19 segs.), 2 juv. 1m (18 segs.), 22 May 2005 ( FMNH) ; and 14.5 mi (23.2 km) E Aberdeen, along east bank of Canyon R., ca. 21.5 mi (34.4 km) N US hwy. 12, N47°18.61', W123° 31.23'; 600' (190 m) asl, 2f, 17 January 2003 ( CAS) , f, 26 May 2003 ( CAS) , and 2f, 2 juv. m (18 segs.), juv. f (18 segs.), 12 December 2004 ( FSCA) .

Diagnosis. With the characters of the genus.

Male syntypes. Adults with 20 segments including epiproct, ca. 12 mm long and 1.3 mm wide, pallid to light yellowish­brown in color.

Head ( Fig. 4 ) covered with fine, variably dense, parallel­sided setae of varying lengths, pilosity becoming denser in interantennal, subantennal, and frontal regions; epicranial suture indistinct; genae extending well beyond adjacent cranial margins. Antennae ( Fig. 4 ) with 7 articles, reaching back to 3 rd tergite, articles 2–7 more densely hirsute than head and becoming progressively more so distad, hairs varying greatly in lengths; antennomere 1 subglobose, 2–5 generally clavate, 5 with slight subdistal swelling on outer surface, 6 enlarged and swollen into rounded lobe on outer surface, 7 with slight lobe proximad on outer margin then narrowing to blunt tip, with four elongated apical cones, lobes and swellings on articles 5–7 possibly representing microsensillae; relative lengths of antennomeres 3>2>4>6=5>7>1.

Dorsum ( Fig. 5 ) smooth, with faint transverse grooves caudal to metatergal midlengths; collum moderately setose, terga 2–4 becoming progressively less setose, 5 with only a few scattered setae dorsally and two or three along caudal margin, terga 6–18 nearly glabrous, with only scattered dorsal setae; ozopores 12 pairs, present on terga 5, 7– 10, 12 & 13, and 15–19. Collum overlapping epicranium, narrower than head but wider than succeeding terga, margins smooth. Tergite 2 slightly narrower than collum, lateral margins lightly dentate with three rounded teeth. Terga 3–4 distinctly narrower, caudal margins curving slightly anteriorly laterad, corners acuminate, margins with faint teeth at anteriolateral corners and midlengths. Tergite 5 distinctly wider than 3 & 4, caudal margin curving anteriorly laterad, caudolateral paranotal corners extended and subacuminate, paranota with two moderately distinct teeth spaced equidistantly between caudo­ and anteriolateral corners, ozopores opening sublaterad on swellings between caudolateral corners and first teeth. Non­poriferous terga (nos. 6, 11, & 14) with caudal margins curving only slightly anteriorly laterad, caudolateral paranotal corners subacuminate, paranota with two equidistant marginal teeth. Poriferous terga with caudal margins becoming progressively sublinear, at most curving only imperceptibly anteriorly laterad, marginal paranotal teeth becoming progressively less distinct caudad, fading out completely around tergite 15, caudolateral paranotal corners becoming progressively more acute and distended caudal to tergite 11, ozopores ( Fig. 6 ) apparently valvular, expanding into progressively greater swellings beginning on tergite 13. Tergite 19 lightly setose on dorsal surface and along caudal and paranotal margins, latter smooth, caudolateral corners slightly distended. Epiproct long and apically blunt, extending well beyond level of paraprocts, moderately setose with tufts of 4–5 longer subapical setae.

Strictures strong, distinct. Sterna of pregonopodal segments granular but glabrous, with shallow bicruciform impressions on 5 & 6 and slight elevations adjacent to leg coxae. Postgonopodal sterna smooth and glabrous, with short rounded lobes subtending both pairs of legs on segment 8 and short but distinct spines subtending legs on segments 9–13, those of segments 14–19 with spines only laterad on caudal margins, becoming progressively smaller and indistinct caudad. Gonapophyses short and broad, moderately elevated above ventral surfaces of 2 nd coxae. Legs seemingly becoming slightly longer caudad; podomeres becoming progressively more hirsute distad on each leg, claws gently curved to sublinear. 1 st legs short and incrassate; 2–7 with distinct lobes dorsad on prefemora ( Fig. 4 ) and becoming progressively larger caudad, femora clavate, with suggestions of distal lobes. Postgonopodal legs with strong prefemoral lobes on segments 7–8, becoming progres­sively smaller thereafter and disappearing around segment 18; femora becoming progressively less clavate distad, narrow and essentially sublinear on segments 14–18. Hypoproct semilunar, with two subterminal setae arising from short tubercles. Paraprocts with margins elevated and thickened, with one short non­marginal seta apiece medial to midwidths.

Gonopodal aperture broad, occupying entire width of metazonum and extending slightly into prozonum, caudal margin slightly flared between 9 th legs. Gonopods in situ ( Fig. 4 ) extending directly ventrad from aperture in subparallel arrangement, not overlapping or touching. Gonopod structure as follows ( Figs. 7–11 ): Coxa large, subquadrate, occupying most of each half of aperture. Prefemur basally globose, narrowing then curving ventrad and blending smoothly and continuously into acropodal stem, indistinctly demarcated from latter, giving rise distad to two subventrally directed, secondary processes that envelope and largely obscure the stem; process "A" a broad, distally expanded flange or lamina with projections on both surfaces, arising on medial side of, and broadly fused to, acropodite, medial surface with additional, smaller, distally expanded lamina overlying and closely appressed to main one ( Fig. 10 ), lateral surface cupulate, with slen­ der proximal and distal projections, latter dactyliform or spiniform, former subdivided into spiniform or falcate inner branch, longer than distal projection and extending beyond distal extremities of laminae, and variably sigmoid to spiniform outer branch overlying and obscuring base of inner branch in lateral view ( Fig. 11 ); process "B" an elongate, undivided structure located primarily on lateral side of acropodite, extending ventrad to near level of solenomere, narrowing then expanding around midlength and narrowing again distad into slightly uncinate tip, with or without marginal teeth. Acropodite continuing ventrad beyond fusion with process "A," "distal zone" expanding into moderately broad, cupulate lamella with lightly toothed distal margin; solenomere arising subterminally from fold on lateral margin, narrowing to blunt, recurved tip, subequal in length to, or longer than, breadth of distal lamina. Prostatic groove extending along prefemur and medial surface of acropodal stem at fusion with process "A," curving onto lateral side of distal lamina and onto solenomere, opening terminally.

Female syntype. Length ca. 10.7 mm, width ca. 1.2 mm. Agreeing closely with males in somatic features with following exceptions. Head and anterior segments considerably less setose; 19 th tergite with only two paranotal setae and a row of six setae along caudal margin. Epicranial suture moderately distinct, terminating in epicranial region. Collum narrower than head and 2 nd tergite. Lateral paranotal margins essentially smooth, with only faint, minute teeth at anteriolateral corners; caudolateral corners extended, more so on poriferous segments. Prefemora only slightly expanded into small lobes on legs 2–10; femora clavate, without lobes. Sterna with distinct, transverse depressions between leg pairs, with short spines subtending both legs on segments 7–18 and only caudal legs on segments 5–6. Cyphopod structure as follows ( Fig. 12 ): valves oriented subtransversely in body, broadly ovoid and lightly hirsute, ends rounded; operculum relatively large and rounded.

Variation. As mentioned in the description and shown in figs. 7–11, the male syntypes vary in the lengths of the solenomeres and the configurations of process "B" and the projections from the lateral surfaces of process "A"; furthermore, the latter extend more directly laterad in the male from Quinalt Lake Loop Road, Grays Harbor Co. We present both standard line drawings ( Figs. 10–11 ), prepared from the left gonopod of a male syntype that had been cleared in lactic acid, and SEM photos ( Figs. 7–9 ) of those from another syntype from somewhat similar views. Each shows features that the other technique does not reveal, and to some degree, these differences are attributable to different perspectives, the SEM photos being from more "head on" ventral views such that the projections, particularly the lateral ones of process "A," appear foreshortened. Process "B" and the solenomere on the SEM specimen seem larger and more prominent, and the shape of the former is also somewhat different as there are a couple of minute subterminal teeth on the outer margin. Figure 9 shows that the surface of the solenomere twists, which was not noticeable under light microscopy. However, the additional, smaller lamina on the medial surface of "A" that is evident in light microscopy ( Fig. 10 ) does not show up in the SEM photo ( Fig. 8 ) because it is so closely appressed to the main lamina as to be obliterated by the preparatory gold coating. SEM therefore resolves a single structure, but the position of attachment of the smaller flange is revealed in fig. 8 by the slight elevational change to the left of the speck of debris. There is a general tendency to consider SEM as a panacea and superior to light microscopy because the much higher magnifications reveal structural details that are invisible even under high powers on the former, but this situation highlights a shortcoming of SEM. Either the preparatory coating cannot penetrate narrow spaces as between these closely appressed laminae, or it does penetrate but also coats the outer lamella and renders it opaque. In either case, SEM erroneously shows a single structure, and light microscopy is superior in this regard because the two laminae are visible with careful focusing up and down. As many milliped gonopods possess structures that are closely appressed to each other, for example laminae in the polydesmidan family Paradoxosomatidae , workers are cautioned against automatically favoring SEM and ignoring light microscopy altogether, as some features may not be revealed by the former.

Ecology. Leonardesmus injucundus inhabits mixed coniferous and deciduous forests. Conifer species include Douglas­fir ( Pseudotsuga menziesii ), Western Hemlock ( Tsuga heterophylla ), Western Red­cedar ( Thuja plicata ), and Sitka Spruce ( Picea sitchensis ). Red Alder ( Alnus rubra ) is present at all collection localities, and Bigleaf Maple ( Acer macrophylum ) occurs at all but one. The millipeds were collected on level floodplains and steep slopes up to 80 m from streams, and were encountered on the surface, under leaf litter and woody debris, up to 10 cm deep in loose soil, and adhering to the undersides of large embedded rocks. When L. injucundus is present, a slight disturbance of the soil and litter causes the milliped to discharge its defensive secretions, typically before being uncovered and seen, but the pungent aroma ummistakably indicates its presence.

Etymology. Literally translated the specific name means "not appealing" and refers to the unpleasant defensive secretion.

Distribution. Known from four counties in southwestern Washington, between Olympic National Park and the Columbia River ( Fig. 3 ). In addition to the syntypes, the following specimens were examined:

WASHINGTON: Grays Harbor Co., Olympic Nat. For. , Nº47 29', W123º31', m, f, 28 September 2003, WPL ( NCSM) ; Inner Cr. at Quinalt Lake Loop Rd., N47º31.15', W123º49.93', 1m, 1f, juv. m (19 segs.), 3 juv. f (19 segs.), 13 February 2005, WPL, C. Richart ( CAS) ; and Capitol St. For., Porter Creek Cpgd., N46º58.671', W123º15.392', 1juv. m (19 segs.), 1juv. f(19 segs.), 24 January 2005, WPL ( FSCA) . Lewis Co., along 4000 Weyerhauser Rd. , 1.8 mi (2.9 km) from Pe­Ell McDonald Rd. , Stillman Basin, N46º 30.87', W123º12.09', 1,000 ft. (315 m) asl, 2 f, 1juv. m (18 segs.), 4 December 2004, WPL, C. Richart ( VMNH) . Mason Co., 6 mi (9.6 km) W Hoodsport , along WA hwy. 119, N47º26.47', W123º12.35', 2?, 17 February 2003, WPL ( UCD) . Pacific Co., Willapa Hills area ca. 15 mi (24 km) S, 4 mi (6.4 km) E Raymond , Alder Cr. drainage of Naselle R. on Trap Cr. Rd. 5.9 mi (9.4 km) S jct. WA hwy. 6, N46°29.837', W123°38.634', 750 ft. (236 m) asl, 1m, 4f, juv. M (19 segs.), juv. F (18 segs), 19 November 2005, WPL, C. Richart ( CAS) .

Remarks. The discovery of L. injucundus further exemplifies the magnitude of previously undetected diplopod diversity in the PNW that primarily involves small­bodied, cool weather forms. WPL is the first person to sample PNW environments at this time of year, as evidenced by the fact that, despite its strong aroma, L. injucundus had not been discovered; to date his efforts have yielded the new family Microlympiidae (order Chordeumatida ), three other new genera— Microlympia , Leschia ( Chordeumatida : Anthroleucosomatidae ), and Retrorsia ( Polydesmida : Polydesmidae )—and five additional new species ( Shear & Leonard 2003, 2004; Shelley 2003 a; Shelley & Shear 2005). Additional material, presently undescribed and under study by WAS, comprises around a dozen new genera and as many as 50 new species in the orders Chordeumatida and Polydesmida . The steady outpouring of new diplopods that he has sent to us for examination amounts to no less than the unearthing of an entirely new fauna whose existence was not even suspected. Much of the coastal PNW of both the US and Canada is true rainforest environment, which extends northward well into the Alaskan Panhandle. Just as tropical rainforests harbor diverse, speciose faunas, with substantial numbers of undescribed, endemic species, the same holds for North America's only rainforests even though they lie primarily in the northern half of the North Temperate Zone. Extensive sampling for diplopods is therefore in order throughout this region.

Figures

FIGURE 1. Leonardesmus injucundus syntype from Grays Harbor Co., Washington. Photo by W. P. Leonard.

FIGURES 4–6. 4, SEM photo of head and segments 1–7 of male syntype, ventrolateral view from left side; 5, midbody tergite of poriferous segment of the same, dorsal view; 6, left ozopore on caudolateral paranotal corner of the same, dorsal view. Magnifications indicated on scale lines.

FIGURES 7–9. 7, SEM photo of left gonopod of male syntype, sublateral view; 8, the same, submedial view; 9, the same, subventral view. Magnifications indicated on scale lines.

FIGURES 10–12. 10, Left gonopod of male syntype, medial view; 11, the same, lateral view; 12, Left cyphopod of female syntype, caudal view. Scale lines for figs 10–11 and fig. 12 = 0.25 mm.

FIGURES 2–3. 2, Distribution of the Nearctodesmidae. The dot in southcentral British Columbia represents the allopatric population of Nearctodesmus insulanus in the Shuswap Region; those in California, Nevada, and Arizona, some covering two closely proximate sites, represent known or published localities for the southwestern "micro­nearctodesmids." 3, Known occurrences of Leonardesmus and L. injucundus.