Riotintobolus bovinus, 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 bovinus sp. nov. Figure 8

Material examined.

1 ♂ holotype, ZFMK MYR940, Madagascar, Province de Toliara, Makay Mts., forêt de galerie, 21°13'27.5"S, 045°19'35.4"E, 531 m, coll. Jean Noel, 30.xi.2010.

Etymology:

bovinus , after the gonopods which resemble the horns of a cow. Noun in apposition.

Diagnosis.

Riotintobolus bovinus sp. nov. shares the absence of a projecting epiproct on the telson only with R. anomalus , R. antafoky sp. nov., R. tsimelahy sp. nov., R. mangatsiaka sp. nov. and R. lavanono sp. nov. The posterior telopod featuring two slender, sharp projections is only shared with R. tsimelahy sp. nov., R. mangatsiaka sp. nov. and R. lavanono sp. nov. R. bovinus sp. nov. differs from R. tsimelahy sp. nov., R. mangatsiaka sp. nov. and R. lavanono sp. nov. in a much smaller segment number and size, and strong differences in the posterior telopod, whose telopodite is uniquely shaped with two sharp processes running parallel to one another resembling a bull’s horn. R. bovinus sp. nov. differs by more than 14% uncorrected p-distance in the COI barcoding gene from all other Riotintobolus species.

Description.

Measurements: 41+0 segments. Ca. 25 mm long (broken), 2.4 mm wide.

Colour (after 10 years in ethanol): Head and body rings grey, appendages red. Ventral site reddish. Posterior margins of body segments and whole margin of collum black. Anal valves black.

Head: each eye with 24-27 ommatidia in six rows. Incisura lateralis open (Fig. 8A ). 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. 8B ). Antennae short, protruding back to segment 3. Length of antennomeres: 1<2>3>4=5=6, second only slightly longer than 3rd. Terminal antennomere with four large sensory cones located together inside a membranous area (Fig. 8B ). 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 (FIg. 8A, B). Gnathal lobe not dissected.

Collum: smooth, laterally not protruding as far as ring 2 (Fig. 8A ).

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 (Fig. 8C ). Epiproct well-rounded, covering, but not reaching above paraproct (Fig. 8C ). Hypoproct inconspicuous (Fig. 8C ).

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 with a tarsal pad, a single apical and two pairs of ventral spines. Length of midbody legs ca. 1.2 times body diameter in males.

Female: unknown.

Male sexual characters: tarsal pads absent (Fig. 8B ). Coxae 3-7 without coxal processes (Fig. 8B ).

Anterior gonopod sternite massive (Fig. 8D ), elongated into a wide, well-rounded triangular lobe (Fig. 8D ). Sternite in anterior view well-visible, without discernible apodemes, protruding almost as high as coxal processes. Coxite with sharp triangular mesal process (Fig. 8D, E ). Telopodite with slender process arising mesally (Fig. 8E ), process apically curved with a short triangular projection (Fig. 8D ), tip well-rounded tip, slightly protruding above lateral margin of telopodite (Fig. 8E ).

Posterior gonopods consisting of two parts, separated by an articulation (Fig. 8F ): a long coxite and a slightly shorter telopodite, efferent duct discharging apically (Fig. 8F, G ). Process of coxite and telopodite standing in same axis (Fig. 8F ). Pair of posterior gonopods located parallel to each other, connected by a small, sclerotised and visible sternite (Fig. 8F ). Basal part of coxite wide, mesally with a large triangular sclerite located on lower level than remaining part (Fig. 8F ). Coxite elongated. Efferent duct running at mesal margin of coxite (Fig. 8F, G ). Telopodite as wide as but slightly shorter than coxite, standing in same axis (Fig. 8F, G ), apically membranous, with two slender apical processes resembling a bull’s horns (Fig. 8F, G ). Mesal process wider and longer than lateral process. Efferent duct seems to be ending at base of mesal process (Fig. 8F, G ).

Remarks.

Riotintobolus bovinus sp. nov. lives in direct sympatry with another species of the genus, Riotintobolus makayi sp. nov. (Fig. 2 ).

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 8. Riotintobolus bovinus sp. nov., male holotype (ZFMK MYR 940) A multi-layer photograph, anterior body, lateral view B multi-layer photograph, leg pairs 1 - 7, ventral view C multi-layer photograph, posterior body end with telson D anterior gonopod, anterior view E anterior gonopod, posterior view F left posterior gonopod, posterior view G left posterior gonopod, anterior view. Abbreviations: Apo = apodeme; av = paraprocts; Co = collum (ring 1); Cx = coxite; Gn = gnathochilarium; Md = basal joints of mandible; Pe = penis; Pre = epiproct; St = sternite; T = telopodite; x = lateral swollen process; y = opening of efferenct duct; numbers refer to leg pair or segment number. Scale bars: 1 mm.