Riotintobolus aridus Wesener, 2009

Wesener, Thomas, Enghoff, Henrik & Sierwald, Petra, 2009, Review of the Spirobolida on Madagascar, with descriptions of twelve new genera, including three genera of ' fire millipedes' (Diplopoda), ZooKeys 19 (19), pp. 1-128 : 53-55

Riotintobolus aridus Wesener , sp. n.

urn:lsid:zoobank.org:act:835C43EF-EB42-4673-8C10-60DBEE26A533

Material examined: Holotype: ♂ (30 mm long), MNHN, Province Toliara, Angavo, à l’est d’Antanimora , probably spiny forest, 24°50’57” S, 45°48’6” E, leg. R. Decary, “sous des pierres”, 19.VI.1927, entrée 17–1927.

Other material examined: 2 ♂, 1 ♀, 10 imm., CASENT 9032799 , Province Toliara, Antafiky , gallery forest, 50 m, 23°28’23” S, 44°4’19” E, leg. Frontier Project, millipede dig (3 m x 3 m), 10.X.2001 ; 2 ♀, 10 imm., CAS MGF009 , Province Toliara, Antafiky , gallery forest, 50 m, 23°29’16” S, 44°4’39” E, leg. Frontier Project, millipede dig (3 m x 3 m), 22.VII.2001 ; 2 ♀, CAS MGF012 , Province Toliara, Antafiky , spiny forest thicket, 150 m, 23°28’24” S, 44°4’23” E, leg. Frontier Project, millipede dig (3 m x 3 m), 30.VII.2001 ; 10 imm., CAS MGF010 , Province Toliara, Antafiky , gallery forest, 70 m, 23°28’45” S, 44°3’59” E, leg. Frontier Project, millipede dig (3m x 3m), 13.X.2001 ; 6 imm., CAS MGF007 , Province Toliara, Antafiky , spiny forest thicket, 80 m, 23°29’16” S, 44°4’39” E, leg. Frontier Project, millipede dig (3 m x 3 m), 14.XI.2001 .

Differential diagnosis: R. aridus has special shaped posterior gonopods, featuring a horn-like process, which is unique and aids in the identification of this species.

Description. Measurements: male holotype with 44 podous and no apodous rings, circa 30 mm long (broken), 2.6 mm wide.

Coloration at legs light brown, ventrally light brown, dorsolaterally dark brown to black, dorsally with a wide light brown stripe, middle of stripe with a row of black spots located anteriorly on each body ring. Colour altogether similar to R. mandenensis .

Eyes with 27 or 28 ocelli arranged in five rows.

Antennae protruding back to body ring 2 ( Fig. 28B ). Legs 3–7 in males with tarsal pads. Male legs reach 0.9 times body diameter ( Fig. 28C ). Preanal process sharp-edged, protruding above anal valves ( Fig. 28A ). Anal valves small, with well-developed lips, groove absent ( Fig. 28A ).

Anterior gonopod sternite apically elevated into a wide lobe with a triangular, wellrounded tip ( Fig. 28D ), almost as high as long mesal coxite process, latter relatively slender, slightly longer than sternite ( Fig. 28D ). Telopodite on posterior side apically with a large triangular, retrorse process ( Fig. 28E ), which projects above coxite and telopodite ( Fig. 28E ).

Posterior gonopods telopodite laterally with two large, finger-shaped processes ( Fig. 28F ). Sperm canal discharging into apical-most process, opening of sperm duct visible in anterior view ( Fig. 28F ). Apically, a large membrane present, not extending into lobes- membrane apically as wide as basally ( Fig. 28G ). Telopodite at mesal margin basally of membrane with a slender, long horn ( Fig. 28G ). In anterior view between horn and membrane with an additional, small finger-shaped process ( Fig. 28F ).

Distribution and ecology: the type specimen collected by R. Decary more than 80 years ago states on the collection label “Angavo, á l’est d’Antanimora”. On Madagascar several places with the name “Angavo” exist, as well as some populated places called Antanimora. However, only a single locality called Angavo is located east of Antanimora. This locality is a hilly area inside the spiny forest region of southern

Madagascar ( Fig. 25 ), and was traced using a recent map ( Moat and Smith 2007). The collection label indicates that the single known specimen of R. aridus was found under a stone. Additional specimens were recently collected circa 250 km east at Antafoky.

Etymology: aridus , adjective, refers to type locality of this species, which is located in one of the driest parts of Madagascar.

Figures

Figure 25. Distribution of the genus Riotintobolus gen. n.

Figure 28. Riotintobolus aridus sp. n., male holotype, A telson B left antenna C left midbody leg D anterior gonopod, anterior view E anterior gonopod, posterior view F posterior gonopods, anterior view G posterior gonopods, posterior view.av = anal valves; Cx = coxite; ho = horn; Md = mandible; Pre = preanal ring; St = sternite; T = telopodite. Scale bars = 1 mm.