Rharodesmus tabarkensis, Akkari, Nesrine & Enghoff, Henrik, 2011

Akkari, Nesrine & Enghoff, Henrik, 2011, Rharodesmus Schubart, 1960 — a tropical element in the North African fauna: a new species from Tunisia and notes on the family Pyrgodesmidae (Diplopoda: Polydesmida), Zootaxa 2985, pp. 55-63 : 57-59

Rharodesmus tabarkensis n. sp.

Figs 1–17

Material examined. 13 3, 8 ƤƤ, 14 juveniles, TUNISIA, Jendouba Governorate, Tabarka, N36°57.8, E8°44.6, alt. <40 m, coastal slope below the Genoese fort, under stones, 9.iii.2009, N. Akkari & H. Enghoff leg. ( ZMUC). Etymology. Named after the type locality, Tabarka (northwestern Tunisia).

Description (all measurements in mm). Whitish to light brownish, 20 body rings in both sexes; length: 7–7.9 (males) and 7–8.2 (females); width of prozona 0.40–0.47 (males) and 0.37–0.52 (females); width of metazona: 0.88–0.95 (males) and 0.80–0.95 (females).

Head transverse; dorsal surface microgranulate, epistome with short scattered setae, labral and supra-labral surface with longer ones ( Fig. 1 ). Antennae claviform and stout ( Fig. 1 ), length of antennomeres: 5=6>3>2=4>7>1. Collum ( Fig. 2 ): anterior margin with 10 distinct lobes; dorsal surface domed with numerous small tubercles and 4 bigger ones on the posterior margin.

Body rings: Prozona with fine longitudinal stripes on the anterior margin, followed by a scaly cellular structure covering most of the surface ( Figs 3, 4 ). Posterior limit of the latter area marked by a row of tooth- shaped (dorsal side) or rectangular (ventral side) cuticular ‘cells’ forming a distinct transverse ridge. Prozona behind ridge (ca. ¼ of the length of prozona) with a regular covering of subhemisphaerical knobs.

Metaterga (following the terminology of Hoffman 1976) with 4 longitudinal–two paramedian and two dorso-lateral—rows of big tubercles ( Fig. 4 ) and additionally smaller ones irregularly scattered over the lateral surfaces. Paraterga surmounted of a pair of big caudolateral tubercles ( Figs 4, 5 , 7, t). The three first body rings following the collum with 2 (sometimes 3) transversal tergal rows ( Fig. 4 ), subsequent body rings with 3 rows ( Fig. 5 ). Tubercles of the posteriormost body rings generally much bigger and strongly protruding caudad. Limbus narrow with regularly denticulate margin ( Fig. 6 ). Paraterga well expanded with 3 lateral lobes on body ring 2 ( Fig. 2 ) then becoming bilobed ( Figs 2, 4 ), except on the poriferous rings. In latter rings, the posterior lobe bifurcating into a big lobe forming the porostele and a smaller posterior one ( Figs 5 , 7, p). Ozopores opening on porosteles, present on body rings 5, 7, 9, 10, 12, 13, 15 and 16 ( Figs 5 , 7, o). Legs almost invisible from above, length of podomeres: tarsus>femur>prefemur>postfemur= tibia>claw. Telson (Fig. 8): epiproct short and subtruncate, ventrally with scattered marginal setae and 4 spinnerets (Fig. 8, s) (cf. Shear 2008); paraprocts each with 2 setae, both located well away from mesal margin; hypoproct subtriangular with 2 strong setae on caudal edge.

FIGURES 7–8. Rharodesmus tabarkensis n. sp., close-up of ozopore and Telson: Fig. 7 Ozopore on the 16th tergite, adult male; Fig. 8 Telson, adult female. Abbreviations: lb: posterior lobe; o: ozopore, s: spinneret-like setae; t: caudolateral tubercle.

Male sexual characters. Tarsus of 1st and 2nd pairs of legs with ca 17 stout, spatulate setae; tibia of these legpairs with a few similar setae (Fig. 9). Coxal gonapophyses on 2nd pair of legs flattened (Fig. 10). Prefemur modified on the 7th and 8th pairs of male legs (Fig. 11): apically protruding into a pointed knob surmounted by a stout and contorted seta emerging from a densely poriferous basal area (Fig. 12).

FIGURES 9–12. Rharodesmus tabarkensis n. sp., secondary sexual characters in male: Fig. 9 Spatulate setae on right second leg; Fig. 10 Flattened coxal gonapophyses on second leg pair; Fig. 11 Modified prefemora on the 7th and 8th pairs of legs; Fig. 12 close up of prefemoral process and seta on the 7th left leg.

Gonopods: in situ with crossing telopodites (Figs 11, 13); coxa voluminous, covering most of the lateral side of the telopodite (Figs 11, 13, c), hemispherical with a granulate surface and a rounded-triangular smooth distal process ( Fig. 14, 15 , sp) surmounting a small setose hump ( Fig. 14, 15 , h), median margin with scattered short setae. Basal part of telopodite consisting of a big subrectangular, transverse, strongly granulated and setose ‘prefemoral’ part ( Fig. 14 , p) linked to the coxa by a small cannula ( Fig. 14 , ca); median margin of ‘prefemoral’ part with stout setae, becoming longer anteriad ( Fig. 14 ). ‘Post-prefemoral’ part of telopodite elongated and distally divided in a short membranous rounded cylindrical branch ( Figs 14, 16 , r) and 2 processes of the same length: process A subrectangular ( Figs 14, 16 , A), folded interolaterad and distally serrated, especially on the margin; process B abruptly expanded distad ( Fig. 16 , B) and bifurcating into an elongated smooth conical process ( Figs 14, 16 , cp) and a shorter truncated one ( Fig. 16 , so) forming the solenomere; seminal groove arising from the bases of processes (A) and (B) and running into a lateral furrow up to the tip of the solenomere.

Figures

FIGURES 1 – 6. Rharodesmus tabarkensis n. sp., adult, morphological details: Fig. 1 Head and first two body rings, adult male, anterior view; Fig. 2 Collum and three subsequent tergites, adult female; Fig. 3 Prozona detail: cellular scaly structure (left), transverse ridge of tooth-shaped cuticular ‘ cells’ and knobby area next to metazona (right), adult female; Fig. 4 Body rings 3 and 4, showing microsculpture of prozona and tubercles of metazona, adult female; Fig. 5 Tubercles on metazona 7 and 8, adult female; Fig 6 Limbus, adult male. Abbreviations: lb: posterior lobe; o: ozopore; p: porostele; t: caudolateral tubercle.

FIGURES 13 – 16. Rharodesmus tabarkensis n. sp., gonopodal structures: Fig. 13 Gonopods in situ, profile; Fig. 14 Right gonopod, mesal view; Fig. 15 Close up of coxal distal process and hemispherical hump; Fig. 16 Left gonopod, antero-mesal view. Abbreviations: A: process A; B: process B; c: coxa, ca: cannula; cp: conical process, h: setose coxal hump; r: rounded process; so: solenomere; p: prefemoral part; sp: smooth distal process.

FIGURE 17. Rharodesmus tabarkensis n. sp. mandible. Arrow pointing at the molar hook.