Riotintobolus aridus Wesener,

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

publication ID 10.3897/zookeys.19.221

publication LSID


persistent identifier

treatment provided by


scientific name

Riotintobolus aridus Wesener

sp. n.

Riotintobolus aridus Wesener  , sp. n.

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.GoogleMaps 

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.2001GoogleMaps  ; 2 ♀, 10 imm., CAS MGF009View Materials, 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.2001GoogleMaps  ; 2 ♀, CAS MGF012View Materials, 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.2001GoogleMaps  ; 10 imm., CAS MGF010View Materials, 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.2001GoogleMaps  ; 6 imm., CAS MGF007View Materials, 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.2001GoogleMaps  .

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. 28BView Figure 28). Legs 3–7 in males with tarsal pads. Male legs reach 0.9 times body diameter ( Fig. 28CView Figure 28). Preanal process sharp-edged, protruding above anal valves ( Fig. 28AView Figure 28). Anal valves small, with well-developed lips, groove absent ( Fig. 28AView Figure 28).

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

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

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. 25View Figure 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.


Museum National d'Histoire Naturelle


California Academy of Sciences