Isotomodes rosae, 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 : 46-48

Isotomodes rosae sp. nov.

( Figs. 1–5)

Size: Males 0,65 mm, females 0,55–0,70 mm. Without pigment and eyes. Integument minutely granulate. Antennae as long as the head.

Antennal segment I with 12 mesosetae, two dorsal microsetae and two ventral sensilla. Antennal segment II with about 21 mesosetae, two basal microsetae and one ventral sensillum. Antennal segment III with about 24 mesosetae. Third antennal segment organ with two globular short sensilla in separate pits, two subcylindrical guard sensilla and one ventrolateral accessory sensillum. Antennal segment IV with about 21 subcylindrical dorsal sensilla; dorsoexternal subapical sensory organ present, consisting of one globular cup microsensillum and one subcylindrical sensillum ( Fig. 2).

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, and with eight posterior setae.

Tibiotarsi I,II,III with 21,21,22 acuminate setae, respectively. Unguis without teeth. Unguiculus lanceolate, half as long as the claw ( Fig. 4).

Ventral chaetotaxy as in Figure 3. Head with 4+4 ventral setae along median line. Thoracic sternites with 2,3,4 setae. Subcoxa I with two macrosetae. Ventral tube with 3+3 distal and 2+2 proximal setae. Furcula present; manubrium longer than dens, with 8+8 posterior setae. Dens with two posterior and two anterior setae ( Fig. 5). Mucro bidentate, separated from dens. Furcal subcoxa with two setae on the anterior half and four setae on the posterior half. Retinaculum with 3+3 teeth and one seta. Female genital plate with 1+1 setae on the anterior valve and 1+1 on the posterior valve. Male genital plate with 3-4+3-4 genital setae and 3+3 circumgenital setae.

Dorsal chaetotaxy as in Figure 1. Head with three dorsomedial setae (seta a 0 present). Axial dorsal chaetotaxy from thorax II to abdomen III as 7,6/3,3,4. 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 setae present between the macrosetae S 1; two setae present between the macrosetae S 3; three microsetae m present; among the posterior Pp -series setae of abdominal segment IV there are 23 setae between the sensilla p 13: 15 thin setae (p 0 + 2 p 2, p 4, p 5, p 7, p 8, p 9, p 11) and 8 thicker setae (2 P 1, P 3, P 6, P 10). Abdominal segment V with 4+4 dorsal microsetae and 1+1 dorsolateral sensilla which are thinner and shorter than the microsetae. Macrosetae of abdominal segment VI all slender, not spine-like. Ventral macrosetae V long, located below P 4.

Type material. Holotype (male) on slide, SPAIN: Picos de Europa, Puerto de Áliva (Cantabria). Moss in meadow, altitude 2500 m, UTM: 30TUN58, 17 August 2001, J.I. Arbea leg. Paratypes: four females on slides, same locality and date . Holotype and two paratypes are deposited in the Zoology Museum at the University of Navarra. Two paratypes are deposited in the private collection of J.I. Arbea .

Discussion. The new species is similar to I. ibanezi Simón & Luciáñez, 1990 in dental chaetotaxy, the three microsetae m on abdominal segment IV, the same chaetotaxy of abdominal segment V and the same structure of retinaculum and ventral tube. It differs from these species through the shape of P 1, P 3 and P 4 setae on abdominal segment VI (see Table 1).

Etymology. I take pleasure in naming this species for my wife, Rosa Gómez.