Setoisenoton pallidus Mesibov, 2010, n. sp.
Creators: name: Mesibov, Robert
Publisher: name: Zenodo
Year: 2010
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Diplopoda
Polydesmida
Dalodesmidae
Setoisenoton
Setoisenoton pallidus

description: Setoisenoton pallidus, n. sp.
Figs 1 A, 2A, 2B, 3A, 3B; map Fig. 5
Holotype. Male. Australia, Tasmania, 5 km S of Renison Bell, 41°50'S 145°25'E (CP680670) ± 1 km, 1 May 1987, N. Platnick, R. Raven and T. Churchill, Berlese [extraction method], rainforest litter, QVM 23:51859.
Paratypes. 15 males, same details as holotype, QVM 23:51794.
Other material examined. 44 males, Bubs Hill, Tas, 42°07'S 145°46'E (CP982367) ± 1 km, 28 April 1987, N. Platnick, R. Raven and T. Churchill, Berlese, QVM 23:51791; 2 males, Mt Rufus, Tas, 42°08'S 146°06'E (DP 250350) ± 5 km, 29 April 1987, N. Platnick, R. Raven and T. Churchill, QVM 23:51792; 10 males, 6 km SE of Strahan, Tas, 42°11'S 145°21'E (CP640280) ± 1 km, 30 April 1987, N. Platnick, R. Raven and T. Churchill, Berlese, QVM 23:51793; 1 male, Andrew River Caves area, Tas, 42°20'S 145°44'E ± 5 km, M.R. Gray and S. Eberhard, March 1988, AM KS96000; 4 males, Anthony Road, Tas, 41°49'48"S 145°37'17"E (CP854680) ± 100 m, 21 April 1989, NRCP personnel, QVM 23:51795; 1 male, Pelion Hut, 3 km S of Mt Oakleigh, Tas, 41°50'S 146°03'E ± 1 km, 30 November 1990, I.D. Naumann, sifted Poa, ANIC 64- 000194; 2 males, Vale of Belvoir, Tas, site 11, 41 °33'04"S 145°53'32"E (DP075993) ± 50 m, 17 March 2010, K. Bonham, QVM 23:51810.
Description. Male approximate measurements: length 5 mm, ring 12 prozonite width 0.5 mm, ring 12 maximum width across paranota 0.6 mm. Recently preserved specimens (QVM 23:51810) uniformly pale (Fig. 1 A).
Male with head 1 1/ 3X as wide as collum; head sparsely setose, vertigial sulcus not apparent; antennal sockets separated by ca 1.7X socket diameter, slightly impressed. Antenna clavate, short, barely reaching ring 3 when manually extended; antennomere 6 widest; relative antennomere lengths (2,3,6)>(4,5,7/8). Collum reniform (convex anteriorly). Tergite 3 shorter than tergites 2, 4; tergites 2, 4 much shorter than metatergite 5. Relative overall widths ring 6>(5, head)>4>(3,2,collum); metatergite widths 6–13 about equal, gradually decreasing 14–18. Ring 2 tergal margin slightly below collum and ring 3 margins; ring 2 laterally with ventral surface concave, but without discrete pit. Waist on diplosegments shallow, without longitudinal ridges; suture well defined. Prozonite and metatergite smooth with flat polygonal texture, in places (notably on metazonite between suture and metatergite) with one side of each cuticular polygon slightly raised. Metatergite with transverse furrow indistinct and with three transverse rows of short, blunt setae. Paranota not swollen, lateral margin thin, nearly level, at about 2/3 ring height in lateral view; anterior margin nearly straight, with small, convex anterolateral shoulder leading to nearly straight lateral margin; 1–3 short setae on lateral margin but no apparent notches; posterolateral corner not produced on anterior rings, but with small, rounded corner tooth on last few rings, bearing very small seta. Limbus composed of flat, irregularly shaped, apically toothed tabs. Spiracles small with circular, slightly raised rims; on diplosegments with anterior spiracle just above anterior leg and with posterior spiracle just above and about midway between anterior and posterior leg bases. Ozopore small, round, near posterolateral corner of metatergite; pore formula 5, 7, 9, 10, 12, 13, 15–18. Sternites about as long as wide, lightly setose, with deep transverse and very shallow longitudinal impressions. Legs with prefemur swollen dorsally, femur less so, swelling maximal on legpairs 3–7. Leg 6 with relative podomere lengths tarsus>(prefemur, femur)>>(tibia, postfemur); tarsus 1.3X as long as femur, nearly straight; femur proportionally longer on posterior legs. Leg 6 with brush setae and sphaerotrichomes tapering, pointed; sphaerotrichomes on postfemur, tibia, tarsus; brush setae on femur, prefemur. Gonopore on slight distomedial bulge of leg 2 coxa. Bases of legpairs 6 and 7 well separated, of legpair 5 slightly separated; coxae of legpairs 4–7 moderately setose medially; no sternal processes or setal brushes. Pre-anal ring lightly setose, hypoproct subtrapezoidal, epiproct rounded-triangular, extending well past anal valves. Spinnerets in square array with ventral pair in shallow recess.
Gonopod aperture ovoid, ca 1/2 width of prozonite, rim raised posterolaterally on either side. Gonocoxa small, subcylindrical, with a few short setae distally on anterior and posterior surfaces, very lightly joined medially. Cannula prominent, inserting low on posteromedial side of telopodite base. Telopodites straight, closely parallel, reaching legpair 3 when retracted. Base of telopodite (Figs 2 A, 2B) small, ovoid, the long distal portion of the telopodite arising from the anterolateral side of the base and leaning slightly medially from that point. Telopodite (Figs 2 A, 2B) divided at ca 3/4 height into (1) a flattened, bluntly pointed, posterior process, directed posterodistally and curving anterodistally; and (2) a slightly flattened, anterior solenomere, longer than posterior process, curving distally, dividing at ca 3/4 solenomere length into a posterior, narrow, strap-like branch bearing the opening of the prostatic groove, and an anterior, expanded, mediolaterally flattened tab with a slightly convex outer edge. Solenomere also with a very small, pointed projection arising posteromedially just below the division into strap and tab. Telopodite also with a small quadrate tab on the anteromedial side of the division between posterior process and solenomere. Prostatic groove running on posteromedial side of telopodite to anterior side of base of solenomere. A few short setae on posterior surface of telopodite base and distal portion of telopodite to 1/3 – 1/2 telopodite height; posteromedial surface of base (near cannula entry) densely and finely setose.
Female not yet recognised (see Remarks).
Distribution. Known from wet eucalypt forest, cool temperate rainforest and subalpine scrub at eight sites over ca 3500 km 2 in northwest Tasmania (Fig. 5).
Etymology. Named for the pale colour of all known specimens.
Remarks. In males from Strahan (Fig. 3 B), Andrew River and the Vale of Belvoir, the solenomere is sinuously curved and bears a rounded, tab-like extension of the posterior surface, and the posterior process of the telopodite is smaller than in males from the type locality (Fig. 3 A) and Anthony Road. Telopodites in males from Bubs Hill and Mt Rufus are intermediate in structure, and I regard this variation as intraspecific and possibly clinal.
S. pallidus co-occurs with several undescribed species of small, pale, H+19 dalodesmids with similar metatergite shape and setation, and no S. pallidus males have been found in copula. For these reasons I am not yet able to assign females to this species.
description: Published as part of Mesibov, Robert, 2010, Two new millipede genera from northwest Tasmania, Australia (Diplopoda: Polydesmida: Dalodesmidae), pp. 53-61 in Zootaxa 2571 on pages 54-58, DOI: 10.5281/zenodo.197398