Hylekobolus Wesener &amp; Enghoff &amp; Sierwald 2009, gen. n.
Creators: name: Wesener, Thomas
name: Enghoff, Henrik
name: Sierwald, Petra
Publisher: name: Zenodo
Year: 2009
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Diplopoda
Spirobolida
Spirobolellidae
Hylekobolus

description: <i>Hylekobolus</i> Wesener, gen. n. urn:lsid:zoobank.org:act: A90561DE-4844-47EF-8654-19C38A402BA5 <b>Type species</b>: <i>Hylekobolus brachiosauroides</i> sp. n. <b>Other species included</b> : <i>H. rufus</i> sp. n. <i>H. griseus</i> sp. n. <i>H. albicollaris</i> sp. n. <i>H. goodmani</i> sp. n. <i>H. montanus</i> sp. n. <i>H. analavelona</i> sp. n. <i>H. latifrons</i> sp. n. <i>H. andasibensis</i> sp. n. <i>H. marojejy</i> sp. n. <i>H. anjanaharibe</i> sp. n. <b>Diagnosis</b>: legs without coxal processes, but coxa 7 in males always twice as wide as coxa 6 (Fig. 55B), a unique feature for Spirobolellidae. The anterior (Figs 55L, N) and posterior gonopods (Figs 55M, O) of <i>Hylekobolus</i> are unique within the order Spirobolida. Coxite of posterior gonopods basally at mesal margin with a triangular sclerite (Figs 55O, 56G, 57H, 58G), a potential apomorphy of <i>Hylekobolus</i>. Species medium-sized (30 mm) to quite large (75 mm) for species of the Spirobolellidae. Anterior part of body rings usually black, dark grey or reddish, posterior third light brown to white (Figs 53 A–C). Telson with a well-rounded preanal process (Figs 55C, 56C), which is however much shorter than in <i>Granitobolus</i> or <i>Pseudocentrobolus</i> species. Anal valves small, lips absent (Figs 55C, 56C, 57E, 58C, 59C, 60C). Collum ventrally not protruding as far as body ring 2, but anteriorly covering first mandibular basal joint as well as part of antenna (Figs 55A, D). Part of head projecting slightly above second mandibular basal joint (Fig. 55D). Such a modified head capsule (Figs 55D, 57C) and collum (Fig. 55A) are similar to the conditions observed in the South American genus <i>Atlanticobolus</i> (Hoffman 1979), as well as the West African genus <i>Amblybolus</i> (Keeton 1964), whose family positions are currently unclear (Hoffman 1980). However, in <i>Hylekobolus</i> only the second mandibular joint and the collum form a shallow cavity for the short antenna (Fig. 56A), while in <i>Amblybolus</i> the area around the ocelli is strongly modified, too (Keeton 1964; Demange and Mauriès 1975). Similar modifications of the head capsule also appear in numerous species of the family Spirobolellidae, for example in the genus <i>Benoitolus</i> from the Seychelles Islands (Mauriès 1980). Male legs with tarsal pads only on legs 3–7 (Fig. 55B). Short and wide tarsus with a single pair of long median setae in legs 8 and beyond (Figs 55H, I), unique for Malagasy millipedes. Body ring 7 in males greatly enlarged, ventrally as wide as two regular body rings (Fig. 57B), a character shared only with the Malagasy genus <i>Spiromimus</i>. Anterior gonopods prominently elongated (Figs 57E, 58D), especially telopodites (Fig. 55N), tips of anterior gonopods well visible, even in non-dissected specimens (Figs 55B, 57B). Posterior gonopod coxite and telopodite fused, slender and conspicuously elongated (Figs 55O, 56G), which is typical for the species of the family. Telopodites arranged face-to-face with one another. Tip of telopodite bent mesally by 60° (Fig. 34D) or (more often) 90° (Fig. 55O). <b>Distribution and ecology</b> : all species of <i>Hylekobolus</i> were collected in rainforest. Most of the species (6 of 11) were found in Southeastern Madagascar (Fig. 54). This could represent a collection artefact since a larger amount of inventory work was conducted around Tolagnaro (Fort Dauphin). That only few species of <i>Hylekobolus</i> occur north of Andasibe is puzzling, as it can hardly be accounted for by the lack of more exhaustive inventories. Of special interest is the occurrence of <i>Hylekobolus analavelona</i> sp. n. in the isolated western rainforest of Analavelona. The Analavelona rainforest is isolated by large areas of dry and spiny forest (in which no <i>Hylekobolus</i> species was recorded yet) from other humid forests (Moat and Smith 2007). Numerous <i>Hylekobolus</i> species are obviously limited in their distribution areas, which have very sharp boundaries (Fig. 54). The mechanisms explaining those boundaries are as little understood as in other Malagasy millipedes. Large numbers of <i>Hylekobolus</i> specimens were found inside dead wood. Single specimens walking on the forest floor were rarely discovered. Two <i>Hylekobolus</i> species were often sympatric (Fig. 54). In such instances, one species was always significantly larger than the other (like <i>H. rufus</i> sp. n. and <i>H. albicollaris</i> sp. n. in Ivorona). <b>Description.</b> <i>Size of males and females</i>: species-specific, species with 42–51 rings, no apodous ring. <i>Colour</i> highly species-specific, but posterior margin of body rings always of lighter. <i>Head</i>: each eye with circa 32–48 ocelli arranged in seven vertical rows (Figs 55A, 56A, 57D, 58A). Labrum with standard three irregular teeth and one row of 10–12 stout marginal setae. Clypeus with two setiferous foveolae on each side (Figs 57B, D). Head around incisura lateralis projecting slightly above basal joints of mandible (Figs 55D, 57C). Head projection and basal mandible joint forming antennal cavity. Antennae short, protruding back to body ring 2 (Figs 55A, 56A, 57A). Relative lengths of antennomeres: 1&lt;&lt;2&gt;3=4=5&lt;6 (Figs 55A, 61A). Terminal antennomere with four large sensory cones located together inside a membranous area (Fig. 61A). Antennomere 5 latero-apically with four rows (Fig. 61B), antennomere 6 with two rows (Fig. 61C) of sensilla basiconica. <i>Gnathochilarium</i> lamellae linguales each with two standard setae located behind one another (Fig. 55E). Stipites each with three apical setae. Mentum not subdivided, basally with several sclerotized ridges (Figs 55E, F). Stipites towards mentum with circa three weakly-developed, sclerotized ledges (Fig. 55G). Hypopharyngeal crest with a field of spine-like structures (Fig. 61D). Central pads of endochilarium separated into two areas, apically with circa eight, basally with&gt;20 sensory cones (Fig. 61D). <i>Mandible</i>: external tooth simple, rounded; mesal tooth with three well-developed cusps and in some species with an additional fourth, shallow cusp (Fig. 61E). Basal most cusp extraordinarily large and sharp-edged (Fig. 61E). Four or five pectinate lamellae. Molar plate towards pectinate lamellae with a large furrow and circa eight smaller posterior furrows (Fig. 61E). <i>Collum:</i> smooth, ventrally not protruding as far as ring 2 (Fig. 57B). Collum covering basal mandibular joint anteriorly (Fig. 55A), as well as part of antenna (Fig. 56A). <i>Body rings:</i> dorsally and laterally with micropunctation, meso- and metazona ventrally with numerous transverse impressions. Ozopores starting at ring 6, touching suture between mesozona and metazona (Fig. 55A). <i>Telson</i>: preanal process protruding, well-rounded, slightly curved ventrally (Figs 55C, 56C, 57E, 58C). Anal valves short, smooth, with neither grooves, nor lips, nor micropunctation (Fig. 55C). Subanal scale inconspicuous (Fig. 55C). <i>Legs</i>: coxae 1 and 2 elongated and fused with sternum, podomeres from prefemur to tarsus in both sexes each with 4–10 ventral/mesal setae. Length of midbody legs in males 0.6–0.7 (Fig. 55H), in females 0.4–0.5 times body diameter (Fig. 55I). Each podomere with a long, apical, ventral seta. Coxae 3 and beyond of rectangular shape (Fig. 55H). Tarsus with a tiny dorso-apical seta and a pair of extraordinary long ventral setae (Figs 55H, I). <i>Male sexual characters</i>: tarsal pads present only on legs 3–7 (Figs 55B, 60A). Coxae 3–7 without processes, but coxa 7 twice as wide as coxa 6 (Figs 55B, 56B, 57B). Ring 7 large, in ventral view twice as wide as normal rings (Figs 55B, 57B). <i>Anterior gonopods</i>: prominently elongated, tips projecting from gonopod pouch (Figs 55B, 57B). Anterior gonopods basally with a small sternal apodeme (Fig. 55L), coxite and telopodite apodeme absent. Sternite always well-developed, but hyaline (sheer), of species-specific shape, either triangular (Fig. 55L), rectangular (Fig. 56D), or well-rounded (Fig. 60D). Coxites wide, in some species mesally with a wide, well-rounded process (Figs 57E, 58D, 59D). Telopodites large, elongated (Fig. 55N), mesally protruding into a wide, well-rounded process (Figs 55N, 56F). Mesal margins of process often large and widely protruding (Figs 56F, 58F). Margins basally of process in some species additionally protruding (Fig. 57G). <i>Posterior gonopods</i> resembling long neck and small head of dinosaurs belonging to the Sauropoda group (Figs 55M, O). Coxite and telopodite fused, a suture partially visible (Fig. 55O). Sternite absent (Figs 55O, 56G), posterior gonopods nevertheless connected via membranes. Coxite conspicuously elongated (Figs 55O, 56G, 57F, H), basally at mesal margin with a triangular sclerite, median part of sclerite membranous (Figs 55O, 56G). Coxite mesally with a single spermatic groove. Telopodites arranged face-to-face with one another, tips bent mesally by 60° (Fig. 64D) or (more often) 90° (Fig. 55O). Apically at lateral margin often with a well-rounded short projection (<i>w</i> in Figs 55M, 56E). Sperm canal apically protruding above telopodite margin (<i>z</i> in Figs 55M, 56E). Telopodite often with an apical process protruding as continuance of tip (<i>x</i> in Figs 55M, 56E). A single membranous lobe (<i>y</i>) often present between (<i>x</i>) and (<i>z</i>) (Figs 55M, 56E), lobe in one species greatly enlarged (Fig. 66B). Apodeme very long, oriented in 90° angle towards gonopod (Figs 55O, 56G, 59G). <i>Female sexual characters:</i> vulva simple, bivalve-like (Fig. 55J), with a small, poorly sclerotized operculum at base (Fig. 55K). Posterior valve apically slightly overlapping anterior one (Fig. 61F). Both valves smooth, sensory cones absent. Two or three rows of setae basally on each valve (Fig. 61F). <b>Etymology</b>: <i>Hylekobolus</i>, Latin, masculine, consisting of “hyleko”, short form of <i>hylekoites</i> Greek, m., dweller in wood, which refers to the ecology of this species, and - <i>bolus</i>.
description: Published as part of <i>Wesener, Thomas, Enghoff, Henrik &amp; Sierwald, Petra, 2009, Review of the Spirobolida on Madagascar, with descriptions of twelve new genera, including three genera of ' fire millipedes' (Diplopoda), pp. 1-128 in ZooKeys 19 (19)</i> on pages 97-100, DOI: 10.3897/zookeys.19.221, http://zenodo.org/record/576503
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