Prionopetalum nessiae, Rosenmejer & Enghoff, 2021

Rosenmejer, Trine & Enghoff, Henrik, 2021, A new giant species of the millipede genus Prionopetalum Attems, 1909 from Mt Kilimanjaro, Tanzania (Diplopoda, Spirostreptida, Odontopygidae), Zootaxa 4950 (3), pp. 561-570 : 562-567

publication ID	https://doi.org/ 10.11646/zootaxa.4950.3.8
publication LSID	lsid:zoobank.org:pub:299D777D-F370-4719-B489-11E9A7213FAE
DOI	https://doi.org/10.5281/zenodo.4649819
persistent identifier	https://treatment.plazi.org/id/03E7B457-4659-4F79-B6D4-FA22FB61FA92
treatment provided by	Plazi
scientific name	Prionopetalum nessiae
status	sp. nov.

Treatment

Prionopetalum nessiae sp. nov.

Figs 1–4 View FIGURE 1 View FIGURE 2 View FIGURE 3 View FIGURE 4 , 5A, C View FIGURE 5 , 6 View FIGURE 6

Diagnosis. Differs from congeners by the combination of a laterobasad coxal spine ( Fig. 3A, B View FIGURE 3 : lcs), a simple, unbranched distal telomere process ( Fig. 4A, C–E View FIGURE 4 : tdp), and a long, slender, distally only very slightly expanded proximal telomere process ( Figs 4A, B, E View FIGURE 4 : tpp, 5C). See also Remarks.

Etymology. The species is named after the shape of the tip of the solenomere, resembling the mythical Loch Ness creature. The name is the genitive case of the creature’s nickname Nessie.

Material studied (total: 13 ♂♂, 7 ♀♀)

Holotype

TANZANIA: ♂, Kilimanjaro region, Moshi Vijijini (rural) district, Mt. Kilimanjaro, savannah plot 2, 906 m a.s.l., 03°22’51.32’’S, 37°29’47.49’’E, 26 Feb. 2014, S. Frederiksen leg. (NHMD 621690).

Paratypes

TANZANIA: 2 ♂♂, 3 ♀♀, Kilimanjaro region, Moshi Vijijini (rural) district, Mt. Kilimanjaro, coffee plantation plot 4, 1124 m a.s.l., 03°16’51.54’’S, 37°19’20.51’’E, 26 Nov. 2013, S. Frederiksen leg. (NHMD 621691, NHMD 621692). •

TANZANIA: 3 ♂♂, 11 mi. (ca 18 km) E of Moshi, 890 m a.s.l., 29 Oct. 1957, E.S. Ross & R.E. Leech leg. (CASENT 9081666).

Other material

TANZANIA: 6 ♂♂, 4 ♀♀, Kilimanjaro Region, Rombo district, at Lake Chala, 880 m a.s.l., 3°18’30”S, 37°41’10”E, 1 Dec. 2020, C. Hemp leg. (CCH) • 1 ♂, same data, except 1 Nov. 2020 (CCH).

Description (based on all specimens)

Size. Males: length 90–110 mm, diameter 6.3–7.7 mm, 65–70 podous rings. Females: length up to 100 mm, diameter up to 7.6 mm, 65–67 podous rings. Both sexes without apodous rings in front of telson. Males from Lake Chala (diameter 7.0– 7.7 mm) are thicker than males from other sites (diameter 6.3–6.8 mm).

Colour. Live colour ( Fig. 1 View FIGURE 1 ) overall orange-brown with dorsal half of metazonites contrasting blackish brown. After 7 years in alcohol, podous rings pale silver fading into dark grey/brown with a golden-brown posterior edge, legs and antennae golden-brown, head capsule grey/brown, fading into golden-brown towards clypeal margin.

Anal valves. Each with a long, pointed dorsal spine, and a weakly defined ventral spine, marginal rim raised, with 3 setae on tubercles.

Limbus ( Fig 2D View FIGURE 2 ). Lobes pointed, almost twice as long as broad.

Male legs. Postfemora and tibiae with large, soft pads, except on the first 6 and the last 5–6 leg pairs. First legpair with rounded-triangular prefemoral lobes ( Fig. 2A–C View FIGURE 2 , pfl in Fig. 2C View FIGURE 2 ).

Sternum 9 ( Fig. 3C View FIGURE 3 ). Wider than long, with distal ends wider than median part. With an anterior median projection pointing in between the gonopods.

Gonopod coxa ( Figs 3A–B View FIGURE 3 , 5A View FIGURE 5 ). Lateral margin straight and entirely smooth. Metaplical oblique/horizontal flange (mof) square with a slightly wider distal end. Metaplical shelf (ms) rounded. Proplical lobe (prl) only visible from anterior view. Laterobasad coxal spine (lcs) thorn-shaped, pointing towards base of coxa. Rhomboidal plate (rhp) sub-oval with an irregular margin.

Gonopod telopodite ( Fig. 4 View FIGURE 4 , 5C View FIGURE 5 ). With a long post-torsal spine (pts) describing a flattened curve away from post-torsal narrowing, with apex close to distal end of the basomere (ba). Solenomere (slm) simple, with a slender apex ending in an S-shaped curve. Telomere with a large proximal lobe (pxl), with a wrinkled area on apical surface. Proximal telomere process (tpp) slender with a slightly broader distal end, and a rounded apex ( Fig. 5C View FIGURE 5 ). Distal telomere process (tdp) twice as broad as solenomere, with distinct spines along apical side, and a pointed apex.

Distribution and habitat

Known from four sites on the southern and eastern slopes of Mt. Kilimanjaro ( Fig. 6 View FIGURE 6 ). Habitats include savanna and a coffee plantation.

Remarks

In the key to species of Prionopetalum by Enghoff (2016b), the new species runs to P. clarum ( Chamberlin, 1927) , with which it shares most gonopodal characters: the shape (straight, pointed) and direction (laterobasad) of the coxal spine (lcs); the simple distal telomeral process (tdp); the shape of the proximal telomere process (tpp) ( Fig. 5C View FIGURE 5 ). The two species differ in body diameter: P. clarum = 5.5 mm (only one male described, though), P. nessiae = 6.3–7.7 mm, and in the gonopod coxa profile ( Fig. 5A, B View FIGURE 5 ). In P. clarum the disto-lateral margin of the coxa is almost straight, only slightly sinuate, whereas in P. nessiae sp. nov., it is distinctly convex; in P. clarum the mesal margin of the distal part of the coxa has a shallow, regularly convex expansion, whereas P. nessiae sp. nov. at this place has a larger subrectangular expansion with an irregularly sinuate mesal margin. The gonopod coxa profile of the new species is very similar to that of P. aculeatum Attems, 1914 ( Enghoff 2016b: 18, fig. 9E), in which, however, the proximal telomere process is strongly expanded and asymmetrical ( Enghoff 2016b: 20, fig. 11A).