Isotomodes rafaeli, Arbea, 2006

Arbea, Javier I., 2006, The genus Isotomodes Linnaniemi, 1907 of the Ibero-balearic fauna, with description of two new species (Collembola: Entomobryomorpha: Isotomidae), Zootaxa 1351, pp. 45-52 : 48-49

Isotomodes rafaeli sp. nov.

( Figs. 6–11)

Size: Males 0,75–0,85 mm. Without pigment and eyes. Integument minutely granulate. Antennae as long as the head.

Antennal segment III with about 24 setae. Sensory organ of antennal segment III with two globular sensilla in separate pits, two subcylindrical guard sensilla and one ventrolateral accessory sensillum. Antennal segment IV with about 20 subcylindrical dorsal sensilla. Dorsoexternal subapical sensory organ present, consisting of one globular cup microsensillum and one subcylindrical sensillum.

Labium typical for the genus (after Fjellberg 1999 and Potapov 2001), with two guard setae on papillae E. Labrum with 4/4,5,4 setae. Postantennal organ broadly elliptical, almost as long as the width of the first antennal segment, with six posterior setae ( Fig. 8).

Tibiotarsi I,II,III with 21,21,22 acuminate setae respectively. Unguis without teeth. Unguiculus lanceolate, half as long as the claw ( Fig. 9).

Abdominal ventral chaetotaxy represented in Figure 7. Thoracic sternites with 2,3,4 setae. Subcoxa I with two macrosetae. Ventral tube with 5+5 distal and 2+2 proximal setae in the posterior margin. Furcula present; manubrium longer than dens, with 12+12 posterior setae. Dens with two posterior and five anterior setae. Mucro bidentate, separated from dens. Furcal subcoxa with three setae on the anterior half and four setae on the posterior half ( Fig. 11). Retinaculum with 3+3 teeth and one seta. Male genital plate with 3+3 genital setae and 2+2 circumgenital setae.

Dorsal chaetotaxy as in Figure 6. Head with three dorsomedial setae (seta a 0 present). Dorsomedial chaetotaxy on thorax and abdomen: 7,6/4,4,5. Macrochaetotaxy: 1,1/ 3,3,3,2+2. Sensillar chaetotaxy: 1,1/2,1,2,2 posterior sensilla (accp) and 3,2/0,1,0,0 lateral sensilla (al); abdominal segments V+VI with a pair of lateroventral sensilla situated just below P 5 and P 6 macrosetae. Abdominal segment IV with the dorsomedial seta dm 2 present. 11–13 setae present between the macrosetae S 1. Two setae present between the macrosetae S 3. Six microsetae m present. Among the posterior Pp -series setae of abdominal segment IV there are 25 setae between the sensilla p 13: 17 thin setae (p 0 + 2 p 2, p 4, p 5, p 7, p 8, p 9, p 11, p 12) and 8 thicker setae (2 P 1, P 3, P 6, P 10). Abdominal segment V with a pair of long dorsal macrosetae, 4+4 dorsal microsetae and 1+1 dorsolateral sensilla which are thiner and shorter than the microsetae. Macrosetae of abdominal segment VI all slender, not spine-like. Medial macroseta P 0 almost as broad basally as P 2. The macrosetae P 3 and P 4 are slightly thicker and blunt ( Fig. 10). Ventral macrosetae V long, located below P 4.

Type material. Holotype (male) on slide, SPAIN: Isla Grosa, La Manga (Murcia). Soil under Phagnalon saxatile , 8 April 1978, J.J. Presa leg. Paratypes: one male and three young specimens (body length up to 0,65 mm) on slides, same locality and date. All specimes are deposited in the Zoology Museum at the University of Navarra .

Discussion. The closest species is I. sotoensis Simón et al., 1994 , which shares the same number of dental setae, six microsetae m on abdominal segment IV, the same chaetotaxy of abdominal segment V and the same structure of retinaculum and ventral tube. Besides presence of seta p 12 on abdominal segment VI in rafaeli , other differences include the shape of P 1 and P 3 setae on abdominal segment VI (see Table 1).

Etymology. It is my pleasure to name this species for Dr. Rafael Jordana of Navarra University, who encouraged me to beging the study of Collembola for more than 20 years ago.