Riotintobolus minutus 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: 52-53

publication ID

http://doi.org/ 10.3897/zookeys.19.221

publication LSID

lsid:zoobank.org:pub:C473F9F6-1AE7-4B3F-B17F-CA1C2709010C

DOI

http://doi.org/10.5281/zenodo.3791417

persistent identifier

http://treatment.plazi.org/id/1772122E-7834-FFF2-FF01-3C37AC9CE9BB

treatment provided by

Plazi

scientific name

Riotintobolus minutus Wesener
status

sp. n.

Riotintobolus minutus Wesener   , sp. n.

urn:lsid:zoobank.org:act:69657A54-E55E-4B78-BD6A-C14D398BC1F6

Material examined: 1 ♂, 2 ♀, 2 imm. Holotype: 1 ♂ (22 mm long), FMMC, Province Toliara, Sainte Luce, S 9, littoral forest on sand, in leaf litter (deep), 24°47’ S, 47°10’ E, leg. T. Wesener, 06.IV.2003 GoogleMaps   . Paratypes: 1 ♀, 2 imm., FMMC, same data as holotype GoogleMaps   ; 1 ♀, FMMC W031 B, Sainte Luce, S 9, in leaf litter with roots, 24°46.769’ S, 47°10.288’ E, 12 m, littoral forest on sand, leg. Wesener et al., 01.VI.2007 GoogleMaps   .

Differential diagnosis: R. minutus   is the smallest known species of the genus and with a body length in mature males of only 22 mm, one of the smallest Spirobolida   species known from Madagascar. The pitch-black colour with a thick dorsal red stripe ( Fig. 27A View Figure 27 ) helps to clearly identify this species. The gonopods of this species are in some aspects similar to those of R. mandenensis   and R. anomalus   sp. n.

Description. Measurements: male holotype with 38 podous and 2 apodous rings, 22 mm long, 2.3 mm wide. Females with 39–41 podous and 0–2 apodous body rings, 23–26 mm long, 2.9 mm wide.

Coloration pitch-black, dorsally with an extraordinary wide, red stripe ( Fig. 27A View Figure 27 ). Openings of ozopores highlighted by a red spot ( Fig. 27B View Figure 27 ). Posterior half of collum dorsally black ( Fig. 27E View Figure 27 ). Head, lateral part of anal valves and subanal scale red, legs whitish brown ( Fig.40B View Figure 40 ). Eyes with 12–14 partly fused ocelli arranged in three rows ( Fig. 27E View Figure 27 ). Antennae protruding back to body ring 2 ( Fig. 27B View Figure 27 ). Legs lacking tarsal pads. Male legs reach 0.7 times, female legs 0.5 times, body diameter ( Fig. 27D View Figure 27 ). Preanal process sharp-edged, but not protruding above anal valves ( Fig. 27G View Figure 27 ). Anal valves small, at midanterior part with a deep groove. Margin of lip towards groove sharp-edged ( Fig. 27G View Figure 27 ).

Anterior gonopod sternite apically elevated into a wide lobe with a triangular, wellrounded tip ( Fig. 27H View Figure 27 ). Sternite tip almost as high as mesal coxite process, which is relatively slender but longer than sternite ( Fig. 27H View Figure 27 ). Telopodite on posterior side apically with a large triangular, retrorse process ( Fig. 27J View Figure 27 ), which is projecting above coxite and telopodite margins ( Fig. 27J View Figure 27 ).

Posterior gonopods telopodite laterally with two large, finger-shaped processes ( Fig. 27I View Figure 27 ). Sperm canal discharging at more apical process. Apically, a large membrane present, extending into two lobes, apically twice as wide as basally ( Fig. 27K View Figure 27 ).

Intraspecific variation: females with 39+2 and 41+0 body rings are known, indicating post-mature moults.

Distribution and ecology: this species was only collected in the isolated littoral rainforest on sand in Sainte Luce ( Fig. 25 View Figure 25 ). Only circa 200 ha of this forest will remain after a large scale mining project ( Vincelette et al. 2003, Bollen and Donati 2006). Although officially protected, large scale wood removal and even slash-and-burn agriculture ( Fig. 24C View Figure 24 ) is still ongoing in this forest (own observations in March 2003 and June 2007). The surrounding pseudosteppe is regularly burned, further endangering this forest ( Fig. 24B View Figure 24 ). However, further searches should be conducted in small remaining coastal forests north of Sainte Luce, where this species could also occur. All specimens were found deep in the soil under the wet leaf litter. Disturbed specimens often did not curl into a spiral, but remained motionless and stiff like a stick even when picked up. The giant pill-millipede species Sphaeromimus splendidus Wesener & Sierwald, 2005   and a still undescribed Zoosphaerium   species are currently also only known from the littoral forest of Sainte Luce ( Wesener and Sierwald 2005, Wesener and Wägele 2008).

Etymology: minutus   , adjective, refers to the small size of this species.