Xenylla vanharteni, Weiner & Najt & Paśnik, 2012

Weiner, Wanda Maria, Najt, Judith & Paśnik, Grzegorz, 2012, Collembola Poduromorpha (Entognatha) from continental Yemen and Socotra Island, with the description of a new Xenylla Tullberg, 1869, Zoosystema 34 (3), pp. 553-560 : 555-556

Xenylla vanharteni n. sp.

( Fig. 1 )

TYPE MATERIAL. — Holotype: Yemen, Khamis Bani Sa’d , in leaf litter in banana plantation, 23.VI.1999, A. Van Harten, ♀ ( ISEA Ye-99-3761/1).

Paratypes: same data as holotype, 2 ♂♂ ( ISEA Ye-99- 3761/5-6), 2 ♀♀ ( ISEA Ye-99-3761/2-3), 1 ♀ ( MNHN Ye-99-3761/4) ; same data as holotype, but 31.VIII.1999, 1 ♀ ( ISEA Ye-99-4019) .

TYPE LOCALITY. — Yemen, Khamis Bani Sa’d.

ETYMOLOGY. — This species is cordially dedicated to Antonius Van Harten who kindly collected the studied material.

DIAGNOSIS. — Habitus typical for the genus Xenylla with 5 + 5 eyes, chaetotaxy of “bgklort” type, dens with two chaetea, mucro separated from dens.

DESCRIPTION

Length: holotype 0.85 mm, paratype females 0.94- 1.06 mm, paratype males 0.86-0.9 mm. Colour: spotted blue, Oc plate dark.Tegumental granulation rather fine.

Antennae as long as head.Ant.I with seven chaetae, Ant. II with 11 chaetae. Sensory organ of antennal segment III consisting of two subcylindrical internal sensilla, two small subcylindrical guard sensilla and ventral ms. Ant. IV with three short subcylindrical sensilla (S7, S8, S9) externo-lateral and one shorter dorsal sensilla (S2), two interno-ventral sensilla (S1 & S3) longer and thiner, small ms placed among two latero-external sensilla, small subapical organite and bilobed apical vesicle ( Fig. 1B ).

5 + 5 eyes present, postantennal organ absent. Buccal cone typical for the genus. Chaetotaxy of labrum: 4/4554.

Chaetotaxy type as “bgklort” (according to Gama 1988), dorsal chaetotaxy as in Figure 1A , with rather short, ordinary chaetae, with thin and long sensory chaetae s, their formula per half tergum: 022/11111. Head with chaeta a0 present, chaeta c1 absent (character b after Gama 1988; Thibaud et al. 2004). Serrated chaeta l3 longer than chaeta l1 (character g). Chaetae m3 and p3 on Th. terga II- III absent (characters k and l). Abd. tergum IV without chaetae m3 (character o) and with p3 (p3 and p4 displaced forwards than p2 and p5 =s). Very small An spines present on Abd. tergum VI. Ventral side of head without chaeta p1 (character r), with chaeta m3. Th. sterna without chaetae (character t). Ventral chaetotaxy as in Figure 1E : chaetae p1 and p6 present, chaeta p2 absent on Abd. sternum II, chaetae a6 and p5 present on Abd. sternum III, Abd. sternum IV with chaeta m1. Ventral tube with 4 +4 chaetae.

Tibiotarsi I, II and III with 19, 19 and 18 chaetae respectively,with capitated chaetae A1 on tibiotarsi I- III and A7 on II-III, with chaetae M and without chaeta B7 on tibiotarsus III. Femora I, II and III with 12, 11 and 10 chaetae respectively, trochanters with 5, 5 and 4 chaetae respectively, coxae I, II and III with 3, 7 and 7 chaetae, Scx2 I, II and III with 0, 2 and 2 chaetae, Scx1 I, II and III with 1, 2 and 3 chaetae respectively. Claws with subapical tooth ( Fig. 1C ).

Furca present, mucro with hook at the top and well-developed lamella separated from dens with two chaetae. Ratio mucro: dens =1: 1.5 ( Fig. 1D, E ). REMARKS

Among the species of Xenylla with 5 + 5 eyes, mucro separated from dens with two chaetae each and chaeta c1 absent on the head (character b, after Thibaud et al. 2004), the new species is most similar to Xenylla kenyensis (chaetotaxy type “bklnorst”) described by Gama (1983) from Kenya. Both species share the following characters (the characters for X. kenyensis after Gama 1983): chaetae a1 and a2, p1 and p2 on Th. terga II and III not deplaced, disposed on the same level, chaeta m3 on the Th. terga II and III absent (character k), chaeta p3 on Th. terga II and III absent (character l), chaeta m3 on Abd. tergum IV absent (character o). On the ventral side of the body they have neither chaeta p1 on the head (character r), nor a pair of chaetae on Th. sterna II-III (character t). Both species differ in the shape of mucro (more hooked in the new species), by chaeta l3 lenght (longer than l1 [character g] in the new species and l1= l 3 in X. kenyensis ), by the presence of chaeta p 3 in the new species (absent in X. kenyensis [character n]), by the chaeta m3 present on the ventral side of the head in the new species and absent in X. kenyensis (character s). The Ant. IV with six sensilla in the new species and by the number of sensilla on Ant. IV (six in the new species, only four in X. kenyensis ).

The new species is also very similar to Xenylla lesnei described by Denis (1935) from Mozambique. However, chaetotaxy of the head and body is lacking in the description and the type material seems to be lost. Dens and mucro have been presented for two specimens (A & B, Denis 1935: figs 3, 6) and probably belong to different species. The following characters are similar in X. lesnei and in the new species: the number of sensilla on Ant. IV segment, the type of dens and mucro, the number of capitated chaetae on tibiotarsi. Both species differ by the size of mucro (71% of dens in the new species and 63-67% in X. lesnei ) by the shape of mucro-dens (more slender, especially in specimen A of X. lesnei ), by the ratio of claw: mucro =1: 1.15-0.95 (for specimens A & B of X. lesnei ) and 1: 0.89 in X. vanharteni n. sp. The interno-ventral sensilla (S1 and S3) in Ant. IV segment are longer and stouter in the new species.

Family BRACHYSTOMELLIDAE Stach, 1949

Figures

FIG. 1. — Xenylla vanharteni n. sp.: A, dorsal chaetotaxy; B, antennal segments III and IV, dorso-lateral view; C, tibiotarsus III; D, dens with mucro; E, ventral chaetotaxy of abdomen. Scale bars: A, E, 0.1 mm; B-D, 0.01 mm.