Ostinobolus Wesener, 2009

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 : 86-89

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

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scientific name

Ostinobolus Wesener

gen. nov.

Ostinobolus Wesener View in CoL , gen. n.


Type species: Ostinobolus rufus View in CoL sp. n.

Other species included: O. stellaris View in CoL sp. n. O. montanus View in CoL sp. n. O. subterraneus View in CoL sp. n.

Diagnosis: the posterior gonopods of Ostinobolus with their apically swollen membranous area (v in Figs 48J View Figure 48 , 50F View Figure 50 , 51G View Figure 51 , 52H) are unique among Spirobolida . Telopodites of anterior gonopod diverse, either inconspicuous ( Fig. 51F View Figure 51 ), or on posterior side apically with a small, non-protruding process ( Fig. 48H View Figure 48 ), or with a large retrorse process ( Fig. 52G View Figure 52 ). Telopodites of posterior gonopod as wide as coxites, arranged face-to-face with one another. First leg pair longer than second ( Fig. 52A View Figure 52 ). Living specimens roll themselves into a double-spiral when disturbed. Natural colour varies between species, red to brown ( Figs 48A, C View Figure 48 , 52A, C View Figure 52 ). Some Ostinobolus species share the habitus and the colour pattern with species of the sympatric living Alluviobolus . The latter, however, differs from the former in the presence of completely different anterior and posterior gonopods. Gnathochilarium with a subdivided mentum and a single sclerotized ledge on each stipites ( Figs 48E View Figure 48 , 52D View Figure 52 ), like in Flagellobolus , Riotintobolus , Pseudocentrobolus , Granitobolus , Caprobolus , Alluviobolus . Species of this genus share fewer characters on the anterior gonopods than other genera of Spirobolida . Especially the placement of the unusual O. subterraneus sp. n. inside Ostinobolus is tentative at best.

Distribution and ecology: species of Ostinobolus could be recorded with four species from the rain- and subhumid forests in Southeastern Madagascar ( Fig. 49 View Figure 49 ). Most species are restricted to the rainforest and littoral rainforest with the exception of O. subterraneus sp. n. which also occurs in the semi-dry forest of Petriky. Specimens of O. rufus sp. n. were always collected on the soil surface, with juveniles feeding 1–2 cm deeper in the leaf litter. The same life style can be suggested for O. stellaris sp. n. and O. montanus sp. n., which share a similar colour pattern and leg length with O. rufus sp. n. O. subterraneus sp. n., however, differs from the other species of the genus in living deeply inside the root horizon of the soil.

Description. Males: length up to 53 mm, diameter up to 4.4 mm. 40–49 podous rings. Female length up to 65 mm, diameter up to 6.3 mm. 40–48 podous rings.

Colour highly species-specific, see species descriptions.

Head: each eye with circa 20–25 ocelli arranged in 4–6 vertical rows ( Figs 48A View Figure 48 , 50A View Figure 50 , 51A View Figure 51 ). O. subterraneus sp. n. with only 6–8 decolorized and fused ocelli ( Fig. 52A View Figure 52 ). Labrum with standard three irregular teeth and a row of 10–12 stout marginal setae. Clypeus with two setiferous foveolae on each side. Antennae of medium length, reaching back to ring 3–5 ( Fig. 51B View Figure 51 ). Relative lengths of antennomeres: 1<<2=3=4=5<6

( Fig. 48A View Figure 48 ). Terminal antennomere with four large sensory cones located together inside a membranous area. Antennomere 5 apically with four rows, antennomere 6 with two rows of sensilla basiconica.

Gnathochilarium unusual ( Fig. 48E View Figure 48 ). Lamellae linguales each with two standard setae located behind one another. Stipites each with three apical setae. Mentum basally subdivided by a conspicuous suture ( Figs 48E View Figure 48 , 52D View Figure 52 ). Stipites towards mentum with a wide sclerotized ledge ( Fig. 48E View Figure 48 ). Hypopharyngeal crest with a field of spine-like structures. Number of sensilla on central pads not counted.

Mandible: external tooth simple, rounded; mesal tooth with three cusps. Six pectinate lamellae. Molar plate with few (6 or 7) transverse furrows, anterior three furrows enlarged, posterior furrows minute.

Collum: smooth, laterally not protruding as far as body ring 2 ( Fig. 48A View Figure 48 ).

Body rings: dorsally and laterally smooth, meso- and metazona ventrally with numerous transverse impressions. Ozopores starting at ring 6, touching suture between mesozona and metazona ( Fig. 48C View Figure 48 ).

Telson: preanal process absent. Anal valves with neither lips, nor grooves, nor micropunctation, but posteriorly elongated. Subanal scale inconspicuous ( Figs 48D View Figure 48 , 50C View Figure 50 , 51C View Figure 51 ).

Legs: coxae 1 and 2 elongated and fused with sternum, podomeres from prefemur to tarsus in both sexes each with 4–10 ventral/mesal setae. First leg pair longer than second ( Fig. 52A View Figure 52 ). Tarsus 2 with only small claw, but 3–6 ventral spines. Length of midbody legs (with exception of O. subterraneus where leg length is reduced) circa 1.2 times body diameter in males ( Fig. 48F View Figure 48 ) and 0.8 times body diameter in females. Each podomere with an apical, ventral seta. Coxae 3 and beyond of cylindrical shape ( Fig. 48F View Figure 48 ). Tarsus with a stout dorso-apical seta and five pairs of ventral setae.

Male sexual characters: coxae 3 and 4 in some species elongated into short cylindrical cone ( Figs 48B View Figure 48 , 51B View Figure 51 ).

Anterior gonopods: median sternal projection triangular, with a wide, well-rounded tip ( Fig. 48G View Figure 48 ). Sternite in most species longer than coxite. Coxite without a process, in anterior view well-visible, in posterior view only laterally present ( Figs 48H View Figure 48 , 51F View Figure 51 ). Telopodite diverse inside the genus, see species-specific descriptions.

Posterior gonopods in situ almost completely covered by anterior gonopod coxite and telopodite. Posterior gonopods coxite and telopodite completely fused, but suture partly visible ( Fig. 48J View Figure 48 ). Sternite sclerotized and well-visible ( Fig. 48J View Figure 48 ). Coxite protruding into a short stem towards telopodite, basally with a single spermatic groove. Telopodite as long and as wide as coxite ( Fig. 48J View Figure 48 ), the former arranged face-to-face with one another. Shape of telopodite species-specific, but apically always with a large, swollen membranous area (v in Figs 48J View Figure 48 , 50F View Figure 50 , 51G View Figure 51 , 52H). Sperm canal discharging mesally, basal to membranous area (w in Figs 48J View Figure 48 , 50F View Figure 50 , 51G View Figure 51 , 52H).

Female sexual characters: vulva simple, bivalve-like, with a small, poorly sclerotized operculum at base. Posterior valve apically overlapping anterior one, both smooth, sensory cones absent. Towards opening, basally on each valve are two or three rows of setae.

Etymology: Ostinobolus , masculine, consists of Ostino - referring to the superficial resemblance of the posterior gonopods to a human femur bone, and -bolus.












Ostinobolus Wesener

Wesener, Thomas, Enghoff, Henrik & Sierwald, Petra 2009

O. stellaris

Wesener & Enghoff & Sierwald 2009

O. montanus

Wesener & Enghoff & Sierwald 2009

O. subterraneus

Wesener & Enghoff & Sierwald 2009
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