Zoosphaerium villosum, Wesener & Sierwald, 2005

Wesener, Thomas & Sierwald, Petra, 2005, New giant pill-millipede species from the littoral forest of Madagascar (Diplopoda, Sphaerotheriida, Zoosphaerium), Zootaxa 1097 (1), pp. 1-60 : 19-28

Zoosphaerium villosum sp. nov

Figs 9–16

Holotype: 1 m, coll. Madagascar, Province Toamasina, Toamasina, Station Forestiére de Tampolo ; 3.–16.IV.1996; relatively undisturbed littoral forest; 17°17.2' S 49°24.5' E; 10 m NN; leg. S. Goodman; FMMC 3958.

Paratypes: 1 m. FMMC 8247; 1 f. FMMC 8248, 1 m. CAS, same coll. data .

Additional material: 1m. FMMC 7828; 4 m. FMMC 7827, same collection data as type­material. 1 m., 3f. coll. Côte Sud­Ouest, leg. Grandidier, MNHN CB016

Diagnosis: The shape of the posterior telopods easily identifies this species as another member of the alluaudi ­species group. Z oosphaerium villosum sp. nov. features unique characters, which separate this species unambiguously from others in the group. Tergites and anal shield are densely covered with short hairs, each hair inserting in a small pit ( Fig. 9b ). Harp on male telopods with two stridulation ridges and the tips of the 3 rd joint of anterior telopods rounded ( Figs. 12a–d ). Furthermore, the shape of the first sternite and shape of the male gonopore differs in Z. villosum from other species of the genus ( Figs. 10a , 13a ).

Similar species: See Table 1 for a comparison with closely related species.

Description: Males (4 specimens): length: 43.2–64.6, width of thoracic shield: 21.1–33.6, height of thoracic shield 12.2–17.4. Females (4 specimens): length: 43.3–57.9, width: 24.25–30.25, height: 12.2–16.1. Body length of males is not significantly greater than those of females.

Coloration: The body is dirty blackish green. Posterior margin of the tergites with a thin dark­brown line. Collum and head dark green. Head, ocelli, antennae and legs green. In alcohol­preserved animals, pieces of the dark green pigment layer break off and brown body tissues become visible.

Head: with some long hairs and numerous setiferous pits mostly around the clypeus and lateral of the eyes. Some long, isolated hairs around the eyes and more distributed on the entire head. Posterior margin of head towards collum with a patch of very short hairs. Edges of antennal socket each with little crenulated teeth and a single short spine.

Antennae: overall shape as in genus description. Very long, with thin, long, cylindrical joints; length of antennomeres: 1>2>3>4=5<6. 6 th antennomere long ( Fig. 14a ), with 35 (25) to 45 sensory cones ( Fig. 14c ). 1 st and 2 nd joints with small crenulated teeth and one invagination each; 3 rd joint with some small crenulated teeth at base ( Fig. 14b ).

Mandible: molar plate process of mandible with a single, sharp furrow near the apical end ( Fig. 16a ); 7 pectinate lamellae with long and thin teeth, number of teeth declining proximally ( Fig. 16b ).

Gnathochilarium: posterior surface with many hairs but fewer hairs on the lingual lamella ( Fig. 15a ). Lateral of palpi is a pit with three sensorial cones ( Fig. 15c ). Epipharynx shaped like in other sphaerotheriid species ( Fig. 15b ).

Collum: anterior margin with three rows of isolated hairs; rest of collum, especially posterior margin with only few isolated hairs. Thoracic shield: A few hairs in the concave lateral extension of the thoracic shield, which are remarkably large in this species. Marginal brim very thin, only anteriorly a little broader ( Fig. 9a ). Underside of thoracic shield with two rounded impressions at the posterior edges.

Tergites: anterior paratergite depression densely covered with hairs and several ridges. Tips of paratergites project posteriorly. Tergites covered with numerous small pits ( Fig. 9b ), some of them with a single hair inserting at the center, giving the body in some specimens a furry look. Posterior margins of tergites with a visible fringe of short hairs, originating from the underside of posterior margin of tergites, the endotergum.

Endotergum: features two rows of marginal bristles. Marginal ridge regularly rounded; proximal of marginal ridge with a distinct band of cuticular patterns ( Fig. 14d ). Inner area covered with numerous hairs and spines. Bristles of endotergum scaly.

Anal shield: rounded, neither bell­shaped nor tapered. Anal shield more densely covered with hairs than tergites. Ventral surface carries two black locking carinae on each side, locking carinae sloping weakly towards the posterior end of the anal shield ( Fig. 10b : 12T = 12 th tergite; As = anal shield; PL = pleurite), posterior one up to three times longer than the anterior one. Locking carinae separated from each other by a distance equal to the length of the shorter carina. Distinct suture present between both carinae. Where the suture reaches the margin of the anal shield, a small, distinct triangular invagination is visible

Legs: tarsi of first leg pair with only three to six, second pair with only five to eight ventral spines, claws only weakly curved and without an apical spine. Tarsi of the following legs with 8–11 ventral spines, curved claws and one apical spine. Coxae of all legs covered at the inside margin with a patch of long hairs, the following leg joints with some isolated, long hairs as well. 9 th pair of legs without coxal lobes and spines. All legs feature a crenulated ridge on the femora ( Fig. 9c ).

Sternite: First sternite with a sclerotized ledge ( Fig. 10a ) and long lobe, the latter reaching towards the beginning of prefemur and curved towards the leg pair. Anterior margin irregularly rounded with one small invagination near the tip, covered with long, isolated hairs. Posterior part of the sternite bald ( Fig. 10a : S = sternite). Sternites three and beyond with a spine like process which reaches almost the stigma opening of the next anterior sternite.

Female sexual characters: 2 nd pair of legs without coxal lobe. Operculum ( Fig. 11b : O) of vulvae small, not reaching upper margin of coxa. Apical margin constricted in the middle (= subreniform), lower margin straight. Exterior and interior plate ( Fig. 11b : EP, IP) of vulvae long and broad, its anterior margin reaching around the base of the operculum; interior plate about 2/3 the size of the operculum, exterior plate only 1/3 the size of the operculum. Cyphopod sclerites consisting of two triangular apical sclerites and a much larger third sclerite shaped like a tuning­fork; all visible as dark structures near the suture of the vulva between inner and exterior plates ( Fig. 11b ).

Subanal plate rounded, center of anterior margin slightly excavated. The washboard with two small, weakly developed, symmetrical stridulation ribs, ending well in front of anterior margin ( Fig. 11a ).

Male sexual characters: male gonopore covered by a single large, broad plate. Sclerotized part of plate with a few long hairs. Second pair of legs without coxal lobe ( Fig. 13a ).

Anterior telopods: with three joints distally of syncoxite, inner margin of first joint with ‘harp’ consisting of one long and one short stridulation ridge, long ridge very strong and regular, curved centrally towards middle of the body, beginning on the posterior margin and ending just in front of the anterior margin of first joint ( Fig. 12a ). Posterior side of second telopod joint at the inside with a projection, which reaches up to half the length of the third joint ( Fig. 12b ). The apical part features round sclerotized spots ( Fig. 12c ). The third joint long and well­rounded, tapering distally, posterior side with large membranous invagination covered with few sclerotized spines, one of them extraordinarily big. Border of invagination with up to 11 sclerotized black teeth positioned juxtaposed the round sclerotized spots of the second joint ( Figs 12b–d ).

Posterior telopods: chela of very specific shape. Third joint very broad, the membranous concavity extending over only a part of the anterior margin. Four nonsclerotized spines, basal spine big, two smaller spines in the middle and a fourth spine on the distal end of the membranous invagination. Posterior side of third joint with oblique sclerotized teeth restricted to the membranous invagination. Immovable finger of second joint thin, but as long as movable finger. Inside of immovable finger invaginated, with round sclerotized knobs juxtaposed the tip of the membranous field of the movable finger (third joint). Remarkable is one short spine on the anterior side near the base of the immovable digit. Base of second and third joint densely covered with hairs, apically almost hairless. Syncoxite and first joint almost hairless. Tips of inner horns of telopod coxa with terminal portion of inner lobe bent posteriorly more than 25 degree. Subanal lobe densely covered with hairs ( Figs 12e–f ).

Distribution & Ecology: This species, belonging to the six largest sphaerotheriid species of the world, is only known from the small littoral forest of Toamasina, and may be endemic in this area. Ecological data, not yet available, may shed light on the function of the dense hair coverage on the tergites of this species. The hairs may have sensorial functions or may keep dirt particles away from the body of the animal. Such suggestions may indicate euedaphic and burrowing habits of this species. Behavioral observations can elucidate the function of the extraordinarily big movable finger of the posterior telopods. The dissected female, collected in the middle of April 1996, did not contain eggs.

Conservation: The fate of this species is dependent on the future of the littoral forest fragment near Toamasina, where the specimens were collected. No other collecting sites have been recorded for this species thus far. All recently published records indicate a very fast destruction of the scattered remaining patches of littoral forest on the east coast of Madagascar ( Dumetz 1999, deGouvenain & Srilander 2003). These large­bodied millipedes play an important, albeit understudied role in the decomposition cycle (Ashwini & Sridhar 2003) and millipede populations will have to be carefully monitored if planned reforestation with endemic plants is to be successful.

Intraspecific variation: The lack of material precludes examination of intraspecific variability. The three males show identical formed telopods. The paratype selected for SEM shows a unique feature in sphaerotheriids, his antennae has seven joints before the small disc carrying the sensory cones.

Figures

FIGURES 9 A–D Z. villosum sp. nov., male holotype. a: habitus; b: 7th paratergite, detail; c: left 9th leg, posterior view; d: 5th left pleurite. Scale bars = 1 mm

FIGURES 10 A–B: Z. villosum sp. nov., male holotype. a: coxa of 1st pair of legs with 1st left sternite, posterior view; b: left closing margins of anal shield. 12T = 12th tergite, As = anal shield, PL = pleurite, S = sternite, Scale bars = 1 mm

FIGURES 11 A–B: Z. villosum sp. nov., female paratype. a: subanal plate with washboard; b:coxa of 2nd left leg pair with vulva. EP = exterior plate, IP = inner plate, O = operculum. Scale bars = 1 mm

FIGURES 12 A–F: Z. villosum sp. nov., male holotype. a: anterior telopods, anterior view; b: inner view of 2–3 joint of right anterior telopod; c: detail of tip of process of 2nd joint of right anterior telopod, inner view; d: right anterior telopod, posterior view; e: posterior pair of telopods, anterior view; f: right posterior telopod, posterior view. IH = inner horns. Scale bars = 1 mm

FIGURE 13 a. villosum sp. nov., male holotype. a: left coxa of 2nd pair of legs with male gonopore, posterior view. Scale bars = 1 mm

FIGURES 14 A–D: Z. villosum sp. nov., male paratype, SEM. a: lateral view on antennae; b: lateral view on antennae joints 1–3; c: apical view on sensorial cones of antennae; d: endotergum, (1) = marginal ridge with external row of marginal bristles, (2) = band of flattened nodules, (3) = internal area.

FIGURES 15 A–C: Z. villosum sp. nov., male paratype, SEM. a: ventral view of gnathochilarium; b: ventral view of epipharynx; c: right palp of gnathochilarium with sensorial cones, dorsal view, arrow = field of sensorial cones, cP = central pads, LL = lingual lamella, P = palpus.

FIGURES 16 A–B: Z. villosum sp. nov., male paratype, SEM. a: left mandible, condylus; b: left mandible, pectinate lamellae.