Riotintobolus antafoky, Wesener, 2020

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

Riotintobolus antafoky sp. nov. Figure 9

Material examined.

Holotype: ♂, CASENT 9032794, MGF007, Madagascar, Province Toliara, Antafoky, 80 m, spiny thicket, 23°29'16"S, 44°4'39"E, coll. Frontier project, millipede dig (3 m x 3 m), 14.xi.2001.

Paratypes: 1 ♂, 1 ♀, CASENT 9032794, same data as holotype

Etymology.

Antafoky, after the type locality, spiny forest of Antafoky (Fig. 2 ). Noun in apposition.

Diagnosis.

R. antafoky sp. nov. shares the flag-like membranous tip of the posterior gonopod with R. mandenensis , R. minutus , R. aridus , R. anomalus and R. makayi sp. nov. R. antafoky sp. nov. shares the absence of tarsal pads only with R. bovinus sp. nov., and the relatively simple tip of the posterior gonopod only with R. anomalus . R. antafoky sp. nov. differs from the sympatric R. anomalus in details of the posterior gonopod, the absence of a dorsal red stripe, the much longer antenna (protruding back to body ring 5), and the much smaller size ( R. anomalus males 45 mm long, 4.3 mm wide, R. antafoky sp. nov. ca. 33 mm long, 3.2 mm wide).

Description.

Measurements (holotype): 51+0 segments, ca. 33 mm long (fragmented) and 3.2 mm wide.

Coloration: segments grey, with a dark grey posterior margin, ozopore highlighted by a black spot. Head, antennae and legs dark grey.

Head: each eye with 34 ommatidia in six rows. Incisura lateralis open. Labrum with standard three irregular teeth and a single row of 10-12 stout marginal setae. Clypeus with two setiferous foveolae on each side. Antennae long, protruding back to segment 5. Terminal antennomere with four large sensory cones located together inside a membranous area. Antennomere 5 and 6 latero-apically with sensilla basiconica.

Gnathochilarium: lamellae linguales each with two standard setae located behind one another. Stipites each with three apical setae. Endochilarium not dissected.

Mandible: Stipes without projection, well rounded. Gnathal lobe not dissected.

Collum: smooth, laterally not protruding as far as ring 2.

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

Telson: paraprocts without lips, abundant micropunctation especially towards edges. Epiproct well-rounded, covering, but not reaching above paraproct. Hypoproct inconspicuous.

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 and a strongly swollen prefemur. Tarsus with two 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 without a tarsal pad, a single apical and two pairs of ventral spines. Length of midbody legs ca. 0.9 times body diameter in males.

Female: not investigated.

Male sexual characters: tarsal pads absent. Coxae 3-7 without coxal processes, but coxae 6 and 7 flattened, rectangular.

Anterior gonopod sternite massive (Fig. 9A ), elongated into a wide, well-rounded triangular lobe (Fig. 9A ). Sternite in anterior view well-visible, without discernible apodemes, protruding almost as high as coxal processes. Coxite with sharp triangular mesal process (Fig. 9A, B ), upper rim bending forward in anterior view (Fig. 9A ). Telopodite with strong process arising mesally (Fig. 9B ), process apically curved with a short triangular projection (Fig. 9A ), tip well-rounded, protruding above lateral margin of telopodite (Fig. 9B ).

Posterior gonopods consisting of two parts, separated by an articulation: a long coxite and a slightly shorter telopodite, efferent duct discharging apically (Fig. 9C, D ). Process of coxite and telopodite standing in same axis (Fig. 9D ). Pair of posterior gonopods located parallel to each other, connected by a small, sclerotised and visible sternite (Fig. 9D ). Basal part of coxite wide, mesally with a triangular sclerite located on lower level than remaining part (Fig. 9C ). Coxite elongated. Efferent duct running at mesal margin of coxite (Fig. 9C, D ). Telopodite as wide as but slightly shorter than coxite, standing in same axis (Fig. 9D ), apically with a membranous ‘flag’ (Fig. 9C, D ). Laterally with sclerotised projection bending laterally and completely surrounded by membranous flag. (Fig. 9C, D ). Efferent duct ending at base of process (Fig. 9C, D ). Apex laterally with weakly developed finger-shaped process.

Remarks.

this species lives in direct sympatry with the much larger R. anomalus .

Figures

Figure 2. Distribution of the newly described Riotintobolus species, as well as of the still undescribed species. Vegetation marks modified from Moat and Smith 2007.

Figure 9. Riotintobolus antafoky sp. nov., holotype (CASENT 9032794) A anterior gonopod, anterior view B anterior gonopod, posterior view C telopodite of left posterior gonopod, anterior view D left posterior gonopod, posterior view. Abbreviations: Cx = coxite; St = sternite; T = telopodite; x = lateral swollen process; y = opening of efferenct duct; z = apical membranous ' flag'. Not to scale.