Tropostreptus severus, Enghoff, Henrik, 2017

Enghoff, Henrik, 2017, A new East African genus of spirostreptid millipedes (Diplopoda, Spirostreptida, Spirostreptidae), with notes on their fungal ectoparasite Rickia gigas, Zootaxa 4273 (4), pp. 501-530 : 524-525

Tropostreptus severus sp. nov.

Figs 2 , 8 H, 15B

Epistreptus austerus: Enghoff et al. (2016) , partim

Diagnosis. A large species of Tropostreptus ( Fig. 2 ). Differs from other species, except T. austerus , by the combination of size and the presence of three apical lobes/processes on the gonopodal metaplica. Differs from T. austerus by the larger size of the lateral proplical lobe (lpl) and the basad-mesad curvature of the telopodital antetorsal process (atp).

Etymology. The name is a Latin adjective meaning “severe” (serious, terrible, awful…) and indirectly refers to the very similar species T. austerus .

Material studied (total: 1 ♂, 1 ♀)

Holotype: TANZANIA: ♂ Morogoro Region, Kanga Mts, Kanga Forest Reserve, 1200 m asl, 25 Nov. 1984, N. Scharff leg. ( ZMUC).

Paratype: TANZANIA: 1 ♀, data as holotype ( ZMUC).

Type locality: TANZANIA: Morogoro Region, Kanga Mts, Kanga Forest Reserve, 1200 m asl.

Description. SIZE ( Fig. 2 ). Length 12 cm (male)–15 (female) cm, vertical body diameter 9.0 mm (male), 11.5 mm (female), 56 (male)–57 (female) podous rings.

COLOUR. After 32 years in alcohol head and antennae orange yellow, collum orange yellow with dark margins, body rings greyish back to suture, then marbled brown, then (posterior 40%) dark brown. Legs brownish yellow. Telson medium brown.

GONOPODS ( Figs 8 H, 15). Sternum triangular, not reaching as far distad as paracoxites, lateral edges slightly convex. Proplica ending in blunt-triangular process (map) separated by conspicuous sinus from very large apicolateral, sub-semicircular lobe (lpl). Apico-lateral lobe (lpl) reaching further distad than process mpl. Metaplica in anterior view basally with straight ridge continuing ca. to mid-length of coxite, apically with rounded-triangular mesal process (map) separated by deep sinus from sub-semicircular mid-distal process which again is separated by deep sinus from lateral birdhead-shaped process, lateral “beak” of the latter long, slender pointed, directed laterad. Mesal process reaching further distad than any other part of gonopod. Telopodite shortly after emergence from coxa with very long, slender, pointed, antetorsal process (atp); direction of process first basad, then meso-basad. Telopodite distal to antetorsal process with triangular flange (fl), distal to flange slender, simple, without outgrowths.

Distribution. Known only from the type locality on Kanga Mt., 1200 m asl. Kanga is an isolated peak in the Nguru Mountains, one of the smaller components of the Eastern Arc ( Menegon et al. 2008).

Coexisting congeners. Coexisting with T. hamatus and T. sigmatospinus in Kanga Forest Reserve, Kanga Mts.

Infection with Rickia gigas . The single female specimen was infested with long-celled Rickia gigas ventrally on rings 2–7 (not only on the posterior margin), and on the lateral/dorsal side of leg-pairs 3–7.

Figures

FIGURE 2. Size of Tropostreptus males, expressed as number of podous rings and midbody vertical diameter. Females reach higher diameters than males. See Figs. 11 and 13 for details on T. hamatus and T. sigmatospinus sp. nov.

FIGURE 8. Tropostretus spp., left gonopods, proplica, anterior view. A: T. hamatus, East Usambara Mts, B: T. hamatus, Udzungwa Mts., C: T. sigmatospinus sp. nov., D: T. microcephalus sp. nov., E: T. droides sp. nov., F: T. kipunji sp. nov., G: T. austerus, H: T. severus sp. nov. — not to scale. The apicolateral proplical lobes (apl) are marked with yellow stars.