Zinagon chilensis ( Silvestri, 1903 )

Korsós, Zoltán & Read, Helen J., 2012, Redescription of Zinagon chilensis (Silvestri, 1903) from Chile, with a species list of Iulomorphidae from the Southern Hemisphere (Diplopoda: Spirostreptida: Epinannolenidea), Zootaxa 3493, pp. 39-48 : 40-44

Zinagon chilensis ( Silvestri, 1903)

Figs 1–13.

Iulomorpha chilensis Silvestri, 1903 : Chile (pp. 9–10, no figs)

Nannolene nigrescens Attems, 1903 : Chile (p. 90): Silvestri 1904 (p. 324, footnote), 1905 (p. 744, listed), Chamberlin 1957 (p. 40, listed)

Dimerogonus chilensis: Silvestri 1904 (p. 324, footnote), 1905 (pp. 744-745, description), Chamberlin 1957 (p. 40, listed)

Zinagon chilensis: Jeekel 2004 (p. 75)

Zinagon osorno Chamberlin, 1957 (pp. 40–42, figs 37–38) NEW SYNONYMY

Material studied: Iulomorpha chilensis Silvestri, 1903: 2 male syntypes (1 dissected for gonopods) – Chile, Coipué, Villa Rica (Museo Civico di Storia Naturale “Giacomo Doria”, Genova)

Zinagon osorno Chamberlin, 1957: 9 males and 6 females (2 dissected for gonopods, all broken into several fragments) – Chile, Osorno , 10 km east of Puyehue, 24 January 1951, leg. E. Ross & A. E. Michelbacher (No. 16686, Department of Entomology, California Academy of Sciences, San Francisco, labeled as “ Zinagon chilensis ” manuscript name? sig. by R.L. Hoffman 1976)

New material ( BMNH): 1 male—Chile, Region X (Los Lagos), Osorno Province, Puyehue National Park, on trail El Pionero from Aguas Calientes, humid evergreen forest with Nothofagus dombeyi , found in some sawn logs and sawdust, 28 November 2001, leg. H. J. Read & M. Frater. 1 male, 1 female—Chile, Region X (Los Lagos), Osorno Province, Puyehue National Park, Aguas Calientes, on a walk to view point above Laguna Toro, humid evergreen forest with Podocarpus, under logs, 18 February 2006, leg. H. J. Read & M. Frater.

Description (based on new material): Length: 25–28 mm, max. midbody diameter: 1.8–2.1 mm, no. of rings: one male 41 podous, 3 apodous, plus telson, other male and female both 42+4+T.

Head (Fig. 5) rounded, with no sculpture, no frontal setae. Frontal plate long, overhanging, bilobal, with 2 teeth in the middle and 4+4 setae on each halves. Gnathochilarium (Fig. 1) typical epinannolenidean, with 2+2 setae on both stipites and lamellae linguales. Antennae of average length, reaching 4th ring if bent backwards, 1st segment short, globose, 3rd longest, antennomeres 2, 4, 5 and 6 subequal in length, 7th very small. Ocellarium (Fig. 5, oc) small ( Fig. 11 ), 11–12 ocelli in only 3 short rows (arrangements: 2–4–6, 1–4–6, 1–4–7).

Collum (Fig. 5) rounded, covering caudal part of head as far as the ocellarium, with one long stria along its anterior margin, and 3 short striae (st) at its lateral corner. Pro- and metazonae smooth, number of strong longitudinal striae below ozopores on rings 1–6 is 12–15, from the 7th body ring onwards only 5–6. Ozopores starting on 6th ring onwards, situated behind suture at about half of metazonal length. Epiproct ( Fig. 10 ) smooth, without striae, with no projection, smoothly overlaying paraprocts, with a weak angle at the upper third of its lateral line, subanal plate triangular with 2–3 short setae, paraprocts glabrous, with 2 setae on their lower halves.

Colouration ( Figs 10–11 ): Blackish, dark grey or greyish brown, prozonae slightly paler, legs, antennae and posterior edge of paraprocts pale yellowish. Head dark, in anterior view with light patches around antennal socket and with a pair of small light spots in between and slightly above an imaginary line between the antennae. Anterior edge of collum darker. Lateral area around ozopores on each ring lighter. Telson and anal valves dark.

FIGURES 1–5. Zinagon chilensis ( Silvestri, 1903) , male from Osorno Province, Puyehue National Park. 1: Gnathochilarium, ventral view, 2–3: 1st legpair, anterior (2) and posterior (3) view, 4: 2nd legpair with penis, posterior view, 5: Head, left lateral view. Scales 100 μm. For abbreviations, see text.

Male sexual characters: Gnathochilarial stipites slightly expanded. 1st legpair with flattened and widened coxa (Figs 2–3, cx), in anterior aspect with dense lateral field of setae (Fig. 2, hf), prefemur (pf) 3–4 times as wide as long, with blunt, pointed projection (bp) directed anterio-laterad, femur (f) long, normal, bent laterad, postfemur (tf), tibia (ti) and tarsus (t) subequal in length, tarsus without claw. 2nd legpair with long coxa (Fig. 4, cx), 3 times longer than wide, prefemur short, roughly square shaped, femur twice as long as wide, bent laterad, postfemur and tibia subequal in length, tarsus twice as long as wide, with normal claw. Penis (Figs 4, 8, ps) closely behind coxa of 2nd legpair, short, only 1.5 as long as wide, tip widely rounded, with 2+2 long setae. 7th ring (Fig. 9) with narrow projection to encapsulate gonopods. Prozonae constricted more strongly in males than in females.

FIGURES 6–9 Zinagon chilensis ( Silvestri, 1903) , male from Osorno Province, Puyehue National Park. 6–7: Left gonopods, mesal (6) and lateral (7) view, 8: Penis behind 2nd legpair, 9: 7th ring with protrusion, right lateral view. Scales 100 μm. For abbreviations, see text.

Male gonopods (Figs 6–7) situated deep in ring 7, closely packed together, composed of modified 8th and 9th legpairs. Anterior gonopod large, with a basally broad coxite (Fig. 6, cx), somewhat tapering towards tip, with a long, whiplike flagellum (Fig. 6, fl) attached to its base, and with a strong posterior process readily seen on the flat mesal side (Fig. 6, pr); telopodite (Figs 6–7, tp) slightly longer than coxite, shifted laterally but with a mesal process (mp) more-or-less fitting into the hook formed by the posterior process of coxite; apically with a series of 8 strong marginal setae; and with a compact group of setae on its lateral side, considered as a rudimentary terminal podomere (Fig. 7, rp). Posterior gonopods much smaller than anterior, coxite region mesally (longitudinally) divided by a long suture (s), anterior part drawn into a pointed needle (n) as long as coxite itself; posterior region bearing a series of 5 short, toothlike setae along suture; apically with a strongly setose field (Fig. 6, sf), and posterio-laterally with a rudimentary, apically setose telopodite (rt).

Female sexual characters: Vulvae ( Figs 12–13 ) subrectangular, deeply embedded in ring 2, closely behing 2nd legpair, concealed in narrow vulval pocket; each bursa with 4–5 apical setae, valves slender, without hairs; operculum as long as bursa, laterally slightly pointed, with 2 setae on apex. Apodematic tube and appendix not visible.

Distribution. All the records for this species are located in Chile south of Santiago and north of Puerto Montt. The recent collections and that of Chamberlin are in the same region in the Province of Osorno and seem likely to be in native forest. The exact location of the type locality is rather more difficult to establish. There is a village with the name of Coipue much further north, just west of Rancagua but this is a considerable distance from the Puyehue area and likely to have a different climate and habitat.

Remarks. With the new synonymy of Zinagon osorno , the genus erected by Chamberlin (1957) becomes monotypic. He compared it to the Australian Dinocambala Attems, 1911 , also monotypic, emphasizing the difference in the male first legpair: only “prefemur being abruptly thicker than the more distal articles”. This is also true for Eumastigonus ( Korsós & Johns 2009) hence we feel justified to place Zinagon into the family Iulomorphidae .

When Chamberlin (1957) evaluated the results of the collections by the Lund University and the California Academy of Sciences, he found a closer relationship of the Chilean fauna with South Africa, Australia and New Zealand, as opposed to other South American faunas.

Figures

FIGURES 10 – 11. Zinagon chilensis (Silvestri, 1903), syntype male of Z. osorno Chamberlin, 1957, from Osorno, 10 km east of Puyehue. 10: body end with telson, right lateral view, 11: head and first body rings, right lateral view. Without scale. (photo by Z. Korsós)

FIGURES 12 – 13. Zinagon chilensis (Silvestri, 1903), pair of vulvae of syntype female of Z. osorno Chamberlin, 1957, from Osorno, 10 km east of Puyehue. 12: anterior view, 13 posterior view. Scale 0.5 mm.