Dionaeadesmus force Enghoff, 2025

Enghoff, Henrik, Ngute, Alain Senghor K., Mnendendo, Hamidu R., Kivambe, Exaud E., Mhagawale, Waziri, Malanda, Robin C., Mpoto, Athuman & Marshall, Andrew R., 2025, A mountain of millipedes XII. The Chelodesmidae of the Udzungwa Mountains, Tanzania (Diplopoda, Polydesmida), European Journal of Taxonomy 997, pp. 210-255 : 238-243

Dionaeadesmus force Enghoff gen. et sp. nov.

urn:lsid:zoobank.org:act:EDE39835-BCF3-4A30-A5EC-3FF129D9CB29

Figs 1 , 2E , 15–17

Diagnosis

Redundant, genus monotypic.

Etymology

Named after the FoRCE project (see Material and methods). Noun in apposition.

Material examined (total 6 ♂♂, 9 ♀♀)

Holotype

TANZANIA • ♂; Iringa Region, Kilolo District, Kilombero Nature Reserve, Ndundulu , Luala ; 7°46′00.4″ S, 36°29′33.2″ E; 1903 m a.s.l.; 26 Oct. 2021; A. Ngute, R. Malanda, W. Mhagawale, A. Mpoto and A. Marshall leg.; FoRCE Plot 70, closed canopy, litter sifting; COLL.NHMD – ACC.NO. 2022-EN-003; NHMD 1184575.

Paratypes

TANZANIA • 2 ♂♂, 4 ♀♀; same data as for holotype; Ndundulu, Chawemba ; 7°44′54.4″ S, 36°29′02.0″ E; 2256 m a.s.l.; 8 Nov. 2021; FoRCE Plot 81, open canopy; NHMD 1184562 • 1 ♂, 1 ♀; Iringa Region, Mahenge District, West Kilombero Scarp Forest Reserve, Nyumbanitu Mts , S Udekwa Village ; 07°48′ S, 36°21′ E; 2300 m a.s.l.; Dec. 1993; J.O. Svendsen leg.; NHMD 1184576 • 2 ♂♂, 4 ♀♀; same data as for preceding; 1700 m a.s.l.; L.L. Sørensen and J.O. Svendsen leg.; NHMD 1184572 .

Specimens from Luala are very fragile.

Description (males)

SIZE. Length 22–25 mm, max. width 4.6 mm. COLOUR. Specimens from Luala after 3 years in alcohol completely bleached, whitish. Specimens from Nyumbanitu Mts ( Fig. 2E ) after 31 years in alcohol: head and dorsum medium brown, lateral lobes of collum narrowly whitish, paranota of rings 2–3 and of poriferous rings broadly whitish, paranota of non-poriferous rings same colour as rest of ring; antennae, venter, legs and telson light brownish.

HEAD ( Fig. 15A–B ). Labrogenal offset distinct, otherwise as Morogorius . Antennae reaching back to ring 5 when stretched.

COLLUM ( Fig. 15B ). As in Morogorius : an isosceles curved trapezoid with the longer margin anteriorly, lateral corners smoothly rounded, surface granular, especially laterally. Two setae close to anterior margin.

BODY RINGS ( Fig. 15C–E ). Prozonites smooth, with simple, cellular microsculpture. Metazonites flat, granular dorsally and laterally, ~1.4 × as broad as prozonites, apparently without setae, with a prominent transverse sulcus on rings 5–17. Paranota horizontal, those of rings 2–3 slightly projecting forwards, rectangular until ring 12–14, thereafter posterior corners projecting increasingly backwards, triangular. Paranotal microsculpture ( Fig. 16C ) formed by cytoscutes of irregular shape, narrow or amoeba-like branched. Ozopore formula normal (5, 7, 9–10, 12–3, 15–19), ozopores circular, delimited by smooth ring in smooth peritremata on edge of paranota, ca midway between anterior and posterior margin; peritremata protruding from lateral margin of paranota. Sterna broad, with a transverse impression interrupted in the middle and extensive setation along anterior and posterior margins. Sides of body rings ( Fig. 15D ) with a row of small tubercles along posterior margin. Limbus ( Fig. 16D ) with straight margin, consisting of a row of rectangular cells with a dense fringe of threadlike ridges ending in free processes.

LEGS ( Fig. 15G ). Rather stout, without modifications, length ~1.3× maximum body width, length not increasing towards hind end, relative (percentual) length of podomeres (coxa-claw): 8/ 14 / 23 / 14 / 14 /24 / 2.

T ELSON ( Fig. 16A–B ). Preanal ring with several setae along dorsal part of posterior margin; epiproct large, with prominent lateral setiferous tubercles; spinnerets arranged in a trapezoid on a smooth terminal swelling, simple, flanked by 1+1 globular, swellings. Anal valves (paraprocts) unmodified, each with 2 setae, dorsalmost seta on marginal rim, ventralmost seta more lateral, Subanal scale (hypoproct) semicircular, unmodified, with 1+1 marginal setae.

GONAPOPHYSES. Unconspicuous.

GONOPOD APERTURE. Transversely oval, more than twice as broad as long, rim simple.

GONOPODS ( Figs 16E–F , 17 ). No sternal remnant. Coxa (cx) cylindrical, length slightly> diameter, with a strong conical process (cxp) distally on the anterior side; two long setae (as) on anterior surface basal to process, a few setae on lateral surface, and a field of ~15–20 setae on meso-posterior surface. Cannula (ca) stout. Prefemoral part (prf) continuing in same axis as cx, conical, short, length> 1½ × basal diameter, with numerous long setae on ventral and mesal surfaces and a small tooth (prt) distomesally. Efferent canal running on meso-dorsal side of prf, at level of prefemoral tooth (prt) bending laterad into solenomere. A huge prefemoral process (prp) originating dorso-laterally from prf, together with solenomere (slm) forming right angles with main body of prf, longer than solenomere (slm) and accommodating slm in mesal concavity; overall shape of prp like a twisted spoon with a stout shaft, apically bending mesad over tip of slm and ending in a point; dorsal margin of prp with numerous (~20) spikelike processes (msp); mesal surface with a spiked ridge (spr) and additional scattered spikes. Solenomere (slm) in the shape of a ribbon with rolled-in edges, apically dividing into a slender, pointed, curved, ridged branch (the solenomere s. str., sslm) and a broader, simple, pointed branch which may be regarded as a solenophore (sph). A small rectangular process near the base of slm may be regarded as a parasolenomere (ps).

Distribution and habitat

Only known from two sites in the Udzungwa Mountains : Nyumbanitu Mountains and Ndundulu Forest ( Fig. 1 ). Collected at 1700–2300 m a.s.l.

Remarks

A structure similar to the complicated prefemoral process (prp) of Dionaeadesmus force gen. et sp. nov. occurs in Prepodesmus laciniosus ( Attems, 1937) , of uncertain generic affiliation ( Demange & Mauriès 1975) from Congo. This species, however, differs markedly from D. force in having a very short, simple, pointed solenomere ( Attems 1937: “Rinnenast”) and a two-branched solenophore ( Attems 1937: “Tibiotarsus”), and the two taxa are probably not closely related. See also Chamberlin (1952) (as Morphotelus l.).

Figures

Fig. 1. Map of the Udzungwa Mts showing collecting areas for Chelodesmidae Cook, 1895. Yellow squares: Morogorius spp.D: M. divisus Enghoff sp. nov.,L: M. louishanseni Enghoff sp. nov., P: M. pugio Enghoff sp. nov. K: M. kitungulu Enghoff sp. nov., C: M. cochlear Enghoff sp. nov. Red squares: Tanzaniella howelli Hoffman, 1977. Blue squares Dionaeadesmus force Enghoff gen. et sp. nov. Purple squares: Callistocilla dolorotrix Hoffman, 2005. The position of the squares within the green circles/ ovoids does not indicate exact location. Based on Marshall et al. (2010: fig. 1).

Fig. 2. Chelodesmids from the Udzungwa Mts. A. Morogorius divisus Enghoff sp. nov., paratype, ♀ (NHMD 1184699). B. Morogorius louishanseni Enghoff sp. nov., paratype, ♂ (NHMD 1184563). C–D. Tanzaniella howelli Hoffman, 1977. C. Freshly preserved specimen (uncatalogued). D. Female from Mwanihana (NHMD 1184730). E. Dionaeadesmus force Enghoff gen. et sp. nov., paratype, ♀ (NHMD 1184572), rings 11–13 missing. F. Callistocilla dolorotrix Hoffman, 2005, male from Udzungwa Scarp Nature Reserve (NHMD 1184742). Scale bars: A–B, D–F = 2 mm; C not to scale. Photos: S.G. Selvantharan (A–B, D–F), A.R. Marshall (C).

Fig. 15. Dionaeadesmus force Enghoff gen. et sp. nov. A–B. Paratype, ♂ from Ndundulu (NHMD 1184562). C–G. Paratype,♂ from Nyumbanito Mts (NHMD 1184572). A. Head, anterior view.B. Head, collum and ring 2, dorsal view. C. Ring 13, dorsal view. D. Ring 13, lateral view. E. Ring 12, posterior view. F. Sternum of ring 12. G. Legs from ring 12. Abbreviation: lg = labrogenal offset. Scale bars = A–D, F–G = 0.4 mm; E = 1 mm.

Fig. 16. Dionaeadesmus force Enghoff gen. et sp. nov. A, E–F. Paratype, ♂ from Ndundulu (NHMD 1184562). B–D. Paratype, ♂ from Nyumbanito Mts (NHMD 1184572). A. Rings 18–19 and telson, dorsal view. B. Tip of epiproct, with four spinnerets and globular swellings, posterior view. C. Paranotal microsculpture. D. Limbus. E. Right gonopod, submesal view. F. Right gonopod, anterio-mesal view. Abbreviations: as = anterior coxal setae; ca = cannula; cx = coxa; cxp = coxal process; msp = marginal spikes; prf = prefemoral part; prp = prefemoral process; slm = solenomere; sph = solenophore(?); spr = spiked ridge. Scale bars: A = 0.4 mm; B, E–F = 0.1 mm; C–D = 0.01 mm.

Fig. 17. Dionaeadesmus force Enghoff gen. et sp. nov., paratype, ♂ from Nyumbanito Mts (NHMD 1184572), gonopods. A. Dorsal view. B. Ventral view. C. Sublateral (right) view. D. Left telopodite. E. Left solenomere. Abbreviations: as = anterior coxal setae; cxp = coxal process; msp = marginal spikes; prf = prefemoral part; prp = prefemoral process; prt = prefemoral tooth; ps = parasolenomere; sph = solenophore(?); spr = spiked ridge; sslm = solenomere s. str. Scale bars: A–C = 0.2 mm; D = 0.1 mm; E = 0.05 mm.