Tropostreptus sigmatospinus, 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: 513-519

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Tropostreptus sigmatospinus

sp. nov.

Tropostreptus sigmatospinus   sp. nov.

Figs 7 View FIGURE 7 C, 8 C, 12 B, 13

Diagnosis. A medium-sized species of Tropostreptus   ( Figs 2 View FIGURE 2 , 13 View FIGURE 13 ). Differs from other species, except T. hamatus   , by the combination of size, the presence of two (not three) apical processes (map and bh) on the gonopodal metaplica, and the laterad direction and considerable size of the birdhead-shaped process bh. Differs from T. hamatus   by the smaller size of the lateral proplical lobe (lpl) and the much shorter and less curved antetorsal process (atp) of the telopodite.

Etymology. The name is a composite noun in apposition, “sigmato-“ means S-shaped and refers to the antetorsal process.

Material studied (total: 21 ♂♂, 23 ♀♀, 3 juv.)

Holotype: ♂ TANZANIA, Morogoro Region, Udzungwa Mts Natl Park, Sanje Chini camp, 598 m asl, 07°46’24.6”S, 36°53’47.7”E, 17–19.i.2014, T. Pape & N. Scharff leg. ( ZMUC). GoogleMaps  

Paratypes: All from TANZANIA, all in ZMUC, except as noted.

Udzungwa Mts: 1 ♂, 2 ♀♀ data as holotype.— 4 ♂♂, 5 ♀♀ Iringa Region, Iringa District, Udekwa village, Nyambanike Mts, Ukami Forest , 07°41’49”S, 36°25’15”E, vii –xi.1994, D. Moyer leg. GoogleMaps   1 ♂, 3 ♀♀ Iringa region, Iringa district, west Kilombero Scarp Forest Reserve 07°53’19.5”S, 36°23’11.6”E, montane forest 1100–1300 m asl. Plot Ukami , 30.xi.2000, Frontier Tanzania leg. GoogleMaps   1 ♂ Iringa Region, Iringa District, West Kilombero Scarp Forest Reserve , 07°52’00.1”S, 36°22’56.4”E, 1150 m asl, riverine forest, butterfly fall plot, casual collection, 28.viii.2000, Frontier Tanzania leg. GoogleMaps   1 ♂, 3 ♀♀ Morogoro Region, Kilombero District, Mwanihana Forest Reserve, above Sanje , 2000 ft asl, wet forest, i.1980, W.A. Rodgers leg ( VMNH), labelled as holo- and paratypes of “ New species near S. hamatus Dem.   ” by R.L. Hoffman.   1 ♂ Iringa Region, Sanje Falls, Mwanihana Forest N of Ifakara , 5.iv.1981, J. Kielland leg. ( VMNH)   1 ♂, 1 ♀ Morogoro Region, Kilombero District, Lower Kihansi Hydropower Project at Udagaji Gorge , pitfall trap, line 4, 7.xi.1997, J. Kileta leg. (legs yellow, mesal metaplical lobe larger than in Nyambanike specimens).   1 ♂ Iringa region, Matundu Forest Reserve, 400 m asl, 08°5’S, 36°25’E, iii –iv.1996, L. L. Sørensen leg. GoogleMaps  

Uluguru Mts: 1 ♂, 1 ♀ Morogoro Region, Morogoro District, Chamanyani Forest Reserve, Mwuha. Lowland Forest , 07°08’S – 07°13’S, 37°47’E – 37°51’E, 140–400 m asl, ix. 2000, N. Doggart leg, Uluguru Mountains Biodiversity Conservation Project GoogleMaps   . – 1 ♂ Lupanga, East , 1300 m asl, 10.vii.1981, M. Stoltze & N. Scharff leg.   1 ♂, 2 ♀♀ Morogoro Region, Morogoro District, Mkungwe Forest Reserve, lowland submontane Forest , 06°51’S – 06°54’S, 37°51’E – 37°56’E, 400–1000 m asl, viii. 2000, N. Doggart leg, Uluguru Mountains Biodiversity Conservation Project GoogleMaps   .— 1 ♂, 4 ♀♀, 1 juv. Morogoro Region, Morogoro District, Kimboza Forest Reserve S of Morogoro, iii –iv.1983, W.A. Rodgers & students leg. ( VMNH).  

Kanga Mts: 1 ♂, 1 ♀ Kanga Mts, Morogoro Region, Kanga Forest Reserve , 400–500 m asl, 22–25.xi.1984, lowland rain forest, N. Scharff leg.  

Rondo Plateau: 1 ♂, Lindi Region, Lindi District, Rondo Plateau, forest, 850 m asl, 23.ii.1987, J. Kielland leg. ( VMNH).  

Zanzibar: 1 ♂ Zanzibar, South District, Jozani Forest, 21.ix.1983, K.M. Howell leg. On forest floor, in moist leaf litter of ground-water forest in an area in which Pandanus   sp. is dominant species. KMH 2567 ( VMNH)   . 1 ♂ South District, Jozani Forest , i. xii.1984, K.M. Howell & C.A. Msuya leg. In rotting log, ground-water forest. KMH 2939 ( VMNH)   .— 1 ♂, 1 ♀, 2 juv. Zanzibar, Jozani Forest , 10.viii.1981, M. Stoltze & N. Scharff leg., labelled as ” Tropostreptus   sp. nov. ” by R.L. Hoffman.  

Type locality. TANZANIA, Morogoro Region, Udzungwa Mts Natl Park, Sanje Chini camp, 598 m asl, 07°46’24.6”S, 36°53’47.7”E. GoogleMaps  

Description. SIZE ( Fig. 13 View FIGURE 13 ). Length ca. 10 cm; vertical body diameter 6.6–8.8 mm (males), up to 10.8 mm (female); 47–57 podous rings.

COLOUR. After two years in alcohol head yellowish brown, collum brown, rings brownish yellow back to ozopores, then black, then amber; preanal ring anteriorly yellow, then blackish; preanal ring brown, or yellowish anteriorly, anal valves anteriorly yellow, then blackish; legs brown (specimens from Udzungwa Mts). Some other specimens (after 2–33 years in alcohol) with head, collum, legs and/or telson yellow, sometimes contrastingly so. Specimen from Rondo Plateau “dark above, light below”.

GONOPODS ( Figs 7 View FIGURE 7 C, 8C, 12B). Sternum bell-shaped, proportions variable, usually not as high as paracoxites but sometimes just as high, in specimen from Rondo Plateau “house-shaped” as in topotypes of T. hamatus   . Proplica ending in blunt-triangular process (mpl) separated by very shallow sinus from subapico-lateral, subsemicircular lobe (lpl). Triangular process (mpl) reaching far more distad than subsemicircular lobe (lpl). Metaplica apically with mesal rounded tip (map) separated by shallow sinus from birdhead-shaped process (bh); lateral “beak” of the latter long, slender, strongly curved, overall direction laterad, apex pointing distad and/or posteriad. Mesal rounded tip reaching further apicad than bird-head-shaped process. Telopodite shortly after emergence from coxa with long, stout, pointed, slightly sigmoid antetorsal process (atp); direction of process basad-laterad. Telopodite distal to antetorsal process slender, simple, usually without outgrowths, but in one male from Zanzibar with low triangular flange.

Distribution. Quite widespread in Tanzania: Known from the Udzungwa, Uluguru and Kanga Mts in the Eastern Arc, but also from the Rondo Plateau in SE Tanzania and the island of Zanzibar. Altitudinally it extends from near sea level ( Zanzibar) to 1150, possibly 1300 m asl.

Coexisting congeners. Coexisting with T. hamatus   in the Uluguru Mts (Lupanga East and Mkungwe Forest Reserve) and the Udzungwa Mts (Mwanihana Forest Reserve / Udzungwa Mts National Park), and with T. hamatus   and T. severus in Kanga Forest Reserve, Kanga Mt.  

Infection with Rickia gigas   . A female from Udzungwa Mts. National Park, Sanje Chini Camp, was infected with long-celled Rickia gigas   on the inside of the third and fourth legs and on adjacent parts of rings 4–5. A male from the same site was heavily infected with long-celled R. gigas   on the anterior legs, from the first pair to the fourth post-gonopodal pair, on the adjacent parts of the body rings and on the gonopods themselves. A female collected together with this male had a light infection of the long-celled type on the anteriormost legs.

A male from Mkungwe Forest Reserve was heavily infected with long-celled R. gigas   on the legs and adjacent parts of body rings back to ring 20. Two females in the same sample were lightly infected with the long-celled type on the ventral parts of body rings 4–7, one of them also on some legs belonging to these rings.

The male from Kanga Mts had a few long-celled thalli on the ventral side the a few pregonopodal body rings. A male from Zanzibar had long-celled R. gigas   on the anteriormost legs and the gnathochilarium.


Zoological Museum, University of Copenhagen


Virginia Museum of Natural History