Eurytion yungarum, Pereira, Luis A., 2005

Pereira, Luis A., 2005, A new geophilid centipede of the genus Eurytion Attems, 1903 from north­western Argentina. (Chilopoda: Geophilomorpha: Geophilidae), Zootaxa 794, pp. 1-12 : 3-11

Eurytion yungarum n. sp.

( Figs. 1–41 )

Diagnosis: An Eurytion species with circumforaminal rim of coxosternum of second maxillae not elongate and coxal organs arranged in 2 clusters in each coxopleuron. Among the Neotropical species included in the genus Eurytion , only the present species and Eurytion lethifer Crabill, 1968 share these particular traits. Characters in table 1 separate these two species.

Type material examined: Holotype ɗ, 49 pairs of legs, body length 19 mm, from ARGENTINA: Jujuy: 900 m a.s.l., ca. 50 Km W of Fraile Pintado, close to rivers Candelaria and Normenta, 17.IV.1993, L. A. Pereira & S. Coscarón leg. ( MLP). (First maxillae and mandibles in a slide, rest of the body in alcohol).

Etymology: This species is named after the biogeographical Province of the 'Yungas' in which the holotype has been collected.

Description of Male holotype: 49 pairs of legs, body length 19 mm, maximum body width 0.5 mm. Colour (of preserved specimen in alcohol) yellowish with cephalic shield and forcipular segment darker (pale ochreous).

Antennae: relatively short, ca. 2.4 times as long as the cephalic plate, distally slightly attenuate, all articles longer than wide. Setae on antennal articles I­V of different length and few in number; those of remaining articles progressively shorter and more numerous towards the tip of the appendage ( Fig. 1 ). Terminal antennal article (a.a.) with ca. 9 claviform sensilla on the external border and ca. 11 on the internal border. Distal end of this a.a. with ca. 5 very small sensilla apparently not split apically ( Fig. 2 ). Ventral and dorsal surface of a.a. II, V, IX ( Figs. 3–4 ) and XIII with very small specialised sensilla. On the ventral side these sensilla are restricted to an internal latero­apical area and are represented by two different types: a and b. Type a sensilla are very thin and not divided apically, type b sensilla are very similar to those of the apex of the terminal article (a, b, Fig. 3 ). Specialised sensilla on dorsal side are restricted to a latero­apical area and are represented by two different types: a and b, similar to a and b of the ventral side (a, b, Fig. 4 ). Distribution of type a and b sensilla as in table 2.

Cephalic plate: nearly subrectangular with sides curved, distinctly longer than wide (ratio 1.35: 1). Shape and chaetotaxy as in Fig 5 .

Clypeus: with 4 setae located on the clypeal area and 2+2 setae on the middle: remaining clypeal surface without setae ( Fig. 6 ). Clypeal area relatively small, minutely punctate or granulate, not areolate ( Figs. 6, 7 ).

Labrum: mid­piece trapeziform, well developed and sclerotized, with 7 small tuberculate teeth. Side­pieces with 13+13 long hyaline filaments ( Fig. 8 ).

Mandible: pectinate lamella with ca. 14 hyaline teeth with shape as in Figure 9 .

First maxillae: with small lappets on coxosternum; telopodites with well developed lappets almost as long as the telopodite ( Fig. 10 ). Coxosternum without setae; median projections of coxosternum subtriangular, well developed and provided with 3+3 large setae and 3+3 small sensilla. Article II of telopodite with 4+4 ventral setae ( Fig. 10 ), dorsal surface apparently without sensilla.

Second maxillae: coxites with 11+11 setae, medially joined through a narrow, hyaline and non­areolate membranous isthmus only ( Fig. 11 ). Pore surronded by sclerotized rim ( Figs. 12–13 ). Apical claw of telopodite well developed slightly curved internally at the tip ( Fig. 14 ). Chaetotaxy of coxosternum and telopodites as in Figs. 11, 15 .

Forcipular segment: when closed, the telopodites reach the level of the anterior margin of the head or slightly project beyond. Forcipular tergum trapeziform with anterior and posterior margins, respectively, covered by the cephalic plate and the tergum of first legbearing segment; chaetotaxy represented by an irregular transverse row of ca. 4 setae on the middle and a very few additional smaller setae dispersed on the remaining surface. Coxosternum without chitinous lines, middle part of anterior border with two ochreous denticles. Telopodites: trochanteropraefemur with two denticles, both deeply pigmented, proximal denticle shorter than the distal one ( Figs. 16–17 ). Femur and tibia without denticles. Tarsungulum basally with a well developed and deeply pigmented denticle; dorsal and ventral edge of the ungular blade not serrulate. Calyx of poison gland subtriangular ( Figs. 17–18 ). Chaetotaxy of coxosternum and telopodites as in Fig. 16 .

Walking legs: first pair shorter than the second one (ca. 0.85: 1). Praefemur, femur and tibia of legs I–XXV each ventrally with one specially long seta ( Figs. 19–21 ). Remaining legs with shorter setae and similar chaetotaxy ( Fig. 22 ). Claws ventrally with two basal parungues, the anterior larger than the posterior ( Figs. 23–25 ).

Sterna: pore fields present from the second to the penultimate sternum. Fields undivided on sterna II–XIII and divided in two subsymetrical areas on all remaining ones (XIV­XLVIII). Form of fields changing along the trunk as in Figs. 26–33 . Number of pores on selected sterna: on sternum II, 17 pores; on VI, 34; on XII, 45; on XIII, 44; on XIV, 20+18; on XV, 23+15; on XXXVII, 6+7; on XLVIII, 13+18.

Last leg­bearing segment: without pleurites at the sides of praetergum. Praesternum divided along the sagittal plane; shape and chaetotaxy of tergum and sternum as in Figs. 34–35 . Coxopleura slightly protruding at their distal ventral ends, setae numerous on the distal internal area, the remaining surface with less numerous larger setae. Coxal organs arranged in 2+2 clusters. Anterior clusters with ca. 4–5 organs, posterior with ca. 3–4 organs ( Figs. 35–37 ). Pores open on the membrane between coxopleuron and sternum, covered by the latter ( Fig. 35–37 ). Last legs with seven podomeres, form and chaetotaxy as in Figs. 34–35 . Praetarsus unguiform, relatively smaller than those of the remaining legs, basally with a single parunguis ( Figs. 38–39 ).

Terminal segments: intermediate tergum with posterior margin convex, intermediate sternum with posterior margin nearly straight. First genital sternum with posterior border approximately straight in the middle, concave along the sides. Gonopods uniarticulate with ca. 14 setae ( Figs. 35 , 40 ); penis dorsally with 3+3 apical setae ( Fig. 41 ). Anal organs absent.

Remarks: The adult condition of this specimen is indicated by the tubula seminifera full of mature spermatozoa.

Female. Unknown.

Figures

FIGURES 1 – 4. Eurytion yungarum n. sp. (male holotype; ARGENTINA: Jujuy: 50 km west of Fraile Pintado). 1: left antenna, ventral; 2: apical region of left a. a. XIV, ventral; 3: left a. a. IX, ventral (a, b: a, b type setae); 4: left a. a. IX, dorsal (a, b: a, b type setae). Scale bars: 1: 0.3 mm; 2 – 4: 0.05 mm.

FIGURES 5 – 9. Eurytion yungarum n. sp. (male holotype; ARGENTINA: Jujuy: 50 Km west of Fraile Pintado). 5: cephalic shield and base of antennae; 6: clypeus and base of antennae; 7: clypeal area; 8: labrum; 9: right mandible. Scale bars: 5 – 6: 0.3 mm; 7 ­ 9: 0.05 mm.

FIGURES 10 – 15. Eurytion yungarum n. sp. (male holotype; ARGENTINA: Jujuy: 50 Km west of Fraile Pintado). 10: first maxillae, ventral; 11: second maxillae, ventral (a: sclerotized rim); 12: detail of sclerotized rim of coxosternum of right second maxilla, ventral; 13: detail of sclerotized rim of coxosternum of left second maxilla, ventral; 14: claw of left second maxilla, ventral; 15: telopodite of left second maxilla, dorsal. Scale bars: 10, 15: 0.1 mm; 11: 0.3 mm; 12 – 13: 0.05 mm; 14: 0.03 mm.

FIGURES 16 – 25. Eurytion yungarum n. sp. (male holotype, ARGENTINA: Jujuy: 50 Km west of Fraile Pintado). 16: forcipular segment, ventral; 17: detail of poison gland in right forcipular telopodite, ventral; 18: detail of calyx of poison gland in right forcipular telopodite, ventral; 19 – 21: right legs I, II and XI, ventral; 22: left leg XLVIII, ventral; 23: claw of right leg I, postero­ventral; 24: claw of right leg XI, antero­ventral; 25: claw of left leg XLVIII, ventral: Scale bars: 16: 0.4 mm; 17: 0.2 mm; 18, 23 ­ 25: 0.05 mm; 19 – 22: 0.1 mm.

FIGURES 26 – 33. Eurytion yungarum n. sp. (male holotype; ARGENTINA: Jujuy: 50 Km west of Fraile Pintado). 26: sternum II; 27: sternum VI; 28: sternum XII; 29: sternum XIII; 30: sternum XIV; 31: sternum XV; 32: sternum XXXVII; 33: sternum XLVIII. Scale bar: 0.2 mm.

FIGURES 34 – 35. Eurytion yungarum n. sp. (male holotype; ARGENTINA: Jujuy: 50 Km west of Fraile Pintado). 34: last leg­bearing segment and terminal segments, dorsal; 35: last leg­bearing segment and terminal segments, ventral. Scale bar: 0.3 mm.

FIGURES 36 – 41. Eurytion yungarum n. sp. (male holotype; ARGENTINA: Jujuy: 50 Km west of Fraile Pintado). 36: right coxal organs, ventral; 37: left coxal organs, ventral; 38: detail of distal end of last podomere of left last leg, ventral; 39: detail of distal end of last podomere of right last leg, ventral; 40: right gonopode, ventral; 41: penis, dorsal. Scale bar: 0.05 mm.