Riotintobolus mangatsiaka,

Wesener, Thomas, 2020, Ecotone shifts in southern Madagascar: first barcoding data and six new species of the endemic millipede genus Riotintobolus (Spirobolida, Pachybolidae), ZooKeys 953, pp. 1-29: 1

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Riotintobolus mangatsiaka

sp. nov.

Riotintobolus mangatsiaka  sp. nov. Figures 4View Figure 4, 5View Figure 5, 6View Figure 6

Material examined.

1 ♂ holotype, ZFMK MYR9801, Madagascar, PN Andohahela, Mangatsiaka, 24°58.051'S, 046°33.206'E, 90 m, spiny forest, leg. Wesener and Schütte, 23.v.2007.

Paratypes: 7 ♂, 14 ♀, ZFMK MYR938, same data as holotype.

Other material examined.

1 ♂, 1 ♀, FMMC 5413, Province Toliara; RNI d’Andohahela, parcel 2; 120 m; 24°49.0'S, 46°36.6'E; pitfalls, camp 6; leg. S. Goodman 7-15.xii.1995; 1 ♂, FMMC 5379, Province Toliara; RNI d’Andohahela, parcel 2; 120 m; 24°49.0'S, 46°36.6'E; pitfalls, camp 6; leg. S. Goodman 7-15.xii.1995;


Mangatsiaka, after the type locality (Fig. 2View Figure 2), spiny forests next to a site called Mangatsiaka, Andohahela National Parc. Noun in apposition.


Riotintobolus mangatsiaka  sp. nov. shares the absence of a projecting epiproct on the telson only with R. anomalus  , R. antafoky  sp. nov., R. bovinus  sp. nov., R. tsimelahy  sp. nov. and R. lavanono  sp. nov. The posterior telopod featuring two slender, sharp projections is only shared with R. bovinus  sp. nov., R. tsimelahy  sp. nov. and R. lavanono  sp. nov. A posterior gonopod separated into three parts is only shared with R. tsimelahy  sp. nov. and R. lavanono  sp. nov., whose habitus and gonopods look very similar to those of R. mangatsiaka  sp. nov. Both species differ in details of the tip of the posterior gonopod and in the colour of their antennae and legs, which are red in R. mangatsiaka  sp. nov. and dark grey in R. lavanono  sp. nov. R. mangatsiaka  sp. nov. differs from R. tsimelahy  sp. nov. in the presence of just one lateral processes on the posterior gonopod. All three species differ by >11% uncorrected p-distance in the COI barcoding gene.


Measurements: male holotype with 49+0 segments, ca. 42 mm long, 4.1 mm wide. Largest females of type series with 48 to 51+0 segments, up to 52 mm long, 5.4 mm wide.

Colour (in living specimens): Body rings grey, appendages red. Head, paraprocts and posterior margins of body segments darker grey to black (Fig. 4AView Figure 4). Ozopore openings highlighted by black spot (Fig. 4A, BView Figure 4).

Head: each eye with 30-35 ommatidia in six rows. Incisura lateralis open (Fig. 4CView Figure 4). Labrum with standard three irregular teeth and a single row of 10-12 stout marginal setae. Clypeus with two setiferous foveolae on each side (Fig. 4DView Figure 4). Antennae long, protruding back to segment 5. Length of antennomeres: 1<2>3=4=5=6. Second antennomere slenderer but twice as long as first. Terminal antennomere with four large sensory cones located together inside a membranous area (Fig. 5AView Figure 5). Antennomere 5 with 3 rows, antennomere 6 latero-apically with a single row of sensilla basiconica (Fig. 5B-EView Figure 5). Antennomere 6 with an unknown type of at least three sensilla or duct openings located close to disc (Fig. 5D, EView Figure 5).

Gnathochilarium: lamellae linguales each with two standard setae located behind one another. Stipites each with three apical setae. Palpi of similar size (Fig. 5FView Figure 5). Central pads with standard two sets of sensory cones, apical area with ten cones, higher area with ~ 30 (Fig. 5GView Figure 5).

Mandible: Stipes without projection, well rounded (Fig. 4CView Figure 4). Gnathal lobe, external tooth simple, rounded; mesal tooth with three cusps (Fig. 6AView Figure 6). Eight pectinate lamellae. Mesal margin of pectinate area (intermediate area) with ca. four rows of small, slender spines. Molar plate with few, five, transverse furrows (Fig. 6AView Figure 6).

Collum: smooth, laterally not protruding as far as ring 2 (Fig. 4CView Figure 4).

Body rings: ozopores starting at segment 6, marked by a black spot. Located on suture between meso- and metazonite. Rings with smooth, but irregular coriaecous surface, ventrally on metazona with transverse ridges.

Telson: paraprocts elongated, with weak lips, abundant micropunctation especially towards edges (Fig. 4EView Figure 4). Epiproct well-rounded, covering, but not reaching above paraproct (Fig. 4EView Figure 4). Hypoproct inconspicuous (Fig. 4EView Figure 4).

Legs: leg 1 with a large cylindrical coxa, twice as long as other podomeres. Tarsus with three pairs of ventral spines and an apical spine beyond claw. Leg 2 with an elongated coxa. Tarsus with three pairs of ventral spines and a short apical spine. Midbody legs with a rectangular coxa, as long as other podomeres. Each podomere ventrally with a single or a pair of apical setae, tarsus with a single apical spine and three pairs of ventral spines. Length of midbody legs ca. 1.2 times body diameter in males.

Female sexual characters. No tarsal pads, antennae shorter than male, only protruding back to ring 2. Female vulva simple, bivalve-like (Fig. 6BView Figure 6). Anterior plate smaller than posterior plate, opening with one row of setae on each plate, close to operculum.

Male sexual characters: tarsal pads present from leg 3 to midbody, small, inconspicuous (Fig. 4DView Figure 4). Coxae 3-7 without coxal processes, but coxae 3-5 swollen (Fig. 3DView Figure 3).

Anterior gonopod sternite massive (Fig. 4FView Figure 4), elongated into a wide, well-rounded triangular lobe (Fig. 4FView Figure 4). Sternite in anterior view well-visible, without discernible apodemes, protruding almost as high as coxal processes. Coxite with a large, well-rounded mesal process (FIg. 4F, G). Telopodite with process arising mesally (Fig. 4GView Figure 4), process apically curved with a large triangular projection (Fig. 4GView Figure 4), tip well-rounded, slightly protruding above lateral margin of telopodite (Fig. 4FView Figure 4). Whole telopodite process resembling an even-sided triangle.

Posterior gonopods consisting of three parts, separated by sutures or articulations (Fig. 4HView Figure 4): a basal coxite with a slender coxite projection and a slightly shorter telopodite, efferent duct discharging laterally (FIg. 4H, I). Process of coxite and telopodite standing in same axis (Fig. 4HView Figure 4). Pair of posterior gonopods located parallel to each other, connected by a small, sclerotised and visible sternite (Fig. 4HView Figure 4). Basal part of coxite wide, mesally with a large triangular sclerite located on lower level than remaining part (Fig. 4HView Figure 4). Coxite elongated. Efferent duct running at mesal margin of coxite (FIg. 4H, I) before curving to the lateral margin at beginning of telopodite (Fig. 4IView Figure 4). Telopodite as wide as but much shorter than coxite, standing in same axis (FIg. 4H, I), apically membranous, with two slender apical processes both diverging (FIg. 4H, I). Mesal process membranous and wider, lateral process longer, slenderer and sclerotised, efferent duct seems to be ending at base of lateral process (FIg. 4H, I). Base of lateral process with a short, membranous-white projection (Fig. 4IView Figure 4).

Intraspecific variation.

The number of segments varies between 47 and 51.

Live observations.

R. mangatsiaka  sp. nov. could be found in great numbers in the early morning (7-9 a.m.) on the forest floor of the spiny bush. The otherwise dry spiny bush was still quite wet because of dew. No juveniles were observed. Contrary to other Riotintobolus  species, such as R. mandenensis  and R. minutus  , R. mangatsiaka  sp. nov. did not remain stiff like a stick when disturbed, but rolled-up into a spiral (Fig. 4BView Figure 4), a common defence behaviour for juliform millipedes.