Ancistroxenus Schubart, 1947

Duy-Jacquemin, Monique Nguyen, 2002, New species and distribution of the genera Lophoturus and Ancistroxenus (Myriapoda, Diplopoda, Penicillata) in the Caribbean and northern South America, Zoosystema 24 (2), pp. 451-470 : 464-467

Genus Ancistroxenus Schubart, 1947

Ancistroxenus comans ( Loomis, 1934) ( Fig. 5 )

Lophoproctus comans Loomis, 1934: 4 , 5, pl. 1, fig. 1.

Plesioproctus comans – Condé 1964: 61-66, figs 1, 2.

Ancistroxenus comans – Ishii et al. 1999: 247-251, figs 47-52.

MATERIAL EXAMINED. — Colombia. Near Bogotá, Párámo San Cayetano, 3600 m in Espeletia barclayana , 23.VIII.1985, H. Sturm leg., 3 ad., 2 ad.

(85/166 Kol.).

French Guyana. Nouragues, 4°5’N, 52°41’W, 8 km North of Saut Pararé, 110 m, moss, end V.1999, Boistel leg., 2 10 p. l. (described), 1 ind. 10 p. l. and 2 ind. 8 p. l. (not observed). — Mountain Roura, 1.5 km NE Fourgassié, W of the road (damaged forest), litter and downling trunks, 140-150 m, 12. II.1992, J.-P. Mauriès & J.-M. Betsch legs, 1 10 p. l.

Pear Island. Isla del Rey, Panamabay, under bark “Monaùmen”, Enghoff leg., 1 ad. .

DESCRIPTION

Two adults examined (one male and one female) from Colombia

Measurements. Body length (without caudal pencil), 4.10 mm (male); 5 mm (female) (5.70 mm with pencil). Tarsus II length of 13 th leg 269 µm (male), 295 µm (female).

Head. Length of VIth antennal article 2.6 (male) or 3 (female) times longer than broad. VIth article with 16 (male) and 18 (female) sensilla basiconica plus the two thick – intermediate i and posterior p (see Condé 1964) – sensilla situated one above the other. Sensillum coeloconicum c present. Posterior tufts with anterior row of 13 and 14 (male), 16 and 17 (female) trichomes; posteri- or rows of two (male), five and six (female) trichomes. Labrum with two posterior rows of cuticular spines plus some lateral spines below these rows; clypeo-labrum with 10 setae along posterior margin. Palps of gnathochilarium with 24 sensilla (female); 39 and 43 (male).

Trunk. Collum with 83 and 88 trichomes; each lateral protuberance with 14 trichomes in female. Oval cluster of tergites II and VI with 35 to 39 (male), or 54 to 59 (female) trichomes; posterior row II and VI with 31 to 32 (male), or 33 to 40 (female).

Telson . 11 (male) or 17 (female) trichomes a, of which nine (male) or 12 and 15 (female), placed on internal side and four (male) or five (female) on external side of the group of trichomes b-c1-c3.

One female from Pear Island, Isla del Rey

Measurements. Body length (without caudal pencil) 4.20 mm. Tarsus II length of 13 th leg 267 µm.

Head. Length of VIth antennal article three times greater than diameter. VIth left article with 71 sensilla basiconica plus the intermediate i and posterior p sensilla; sensillum coeloconicum c present ( Fig. 5B ); right antenna missing. Posterior tufts of vertex with anterior rows of 25 and 29 trichomes, posterior rows of five and six trichomes. Labrum with one posterior row of cuticular spines; clypeo-labrum with 12 setae along the posterior margin.

Trunk. Collum with 108 and 109 trichomes; lateral protuberance (l.p. in Fig. 5D ) with 19 and 24 trichomes. Tergites II ( Fig. 5E ) and VI with a pair of oval clusters of 37 to 46 trichomes each and a posterior row of 69 and 70 trichomes.

Telson . Eleven trichomes a, of which seven placed on internal side and four on external side of the group of trichomes b-c1-c3.

Stadium VI: three females with 10 pairs of legs from French Guyana

Measurements. Body length (without caudal pencil) 2.70 to 3 mm. Tarsus II length of 10 th leg 220 to 230 µm.

Head. Ratio length to diameter: 2.90 (Nouragues) and 3.50 (Roura). VIth article with 18 and 23 (in first larva), 22 and 23 (in second larva from Nouragues) sensilla basiconica plus the intermediate i and posterior sensilla p; the sensillum coeloconicum c is present. Posterior tufts with anterior row of 10 (once) to 11 trichomes, posterior rows of two (once) to three trichomes. On left antennal article VI, the female from Roura has 15 small proximal sensilla basiconica, 14 usual sized sensilla basiconica plus i, p and c ( Fig. 5A ); right antenna is missing. Labrum with one posterior row of cuticular spines plus some lateral spines below this row.

Telson . Eleven to 14 trichomes a, of which seven to nine placed on internal side and four to seven on external side of the group of trichomes b-c1-c3.

REMARKS

The position and the size of the VIth antennal article sensilla basiconica i and p seem invariable in this species. On the contrary the other sensilla basiconica, which are thinner and shorter than i and p, are variable in number, position and size; some among them are very short, as, for example, in the female from Montagne de Roura in French Guyana ( Fig. 5A ). With a total of 73 sensilla basiconica, the female of Isla del Rey holds the record for sensilla number, previously belonged to a female from Colombia with 31 sensilla ( Terver et al. 1968). A comparison between the two adult females, from Isla del Rey and Colombia, shows that the trichome numbers of the vertex tufts, collum and posterior row on tergites are higher in the female from Isla del Rey (the median interruption of the posterior row is shorter) ; on the contrary, the number of trichomes in the tergite clusters is higher in the female from Párámo San Cayetano in Colombia.

Family POLYXENIDAE Lucas, 1840

Figures

FIG. 5. — Ancistroxenus comans (Loomis, 1934); A, 10 p.l. from French Guyana, Montagne de Roura, VIth left antennal article; B-E, Isla del Rey; B, VIth left antennal article; C, anterior right trichobothrium; D, E, insertions of trichomes on the right half of collum and tergite II. Abbreviations: c, sensillum coeloconicum; i, intermediate sensillum; l.p., lateral protuberance; p, posterior sensillum basiconicum. Scale bars: A-C, 25 µm; D, E, 50 µm.