Folsomiella trisetosa, Mendonça & Fernandes & Abrantes, 2005

Mendonça, Maria Cleide De, Fernandes, Liliane Henriques & Abrantes, Edu- Ardo Assis, 2005, Two new species of Folsomiella Bonet and redescription of F. albida (Arlé, 1959) (Collembola, Brachystomellidae), Zootaxa 1006 (1006), pp. 11-21 : 11-21

Folsomiella trisetosa sp. nov.

( Figs. 1–13)

Length: 0,50–0,87 mm. Entirely white. Body with middle­sized granulation. Chaetotaxy of smooth and thin setae, sparsely distributed; sensorial setae smooth and acuminate, with twice the length of common setae, and arranged at each half­tergite following the formula: 022/21111. Dorsal chaetotaxy as in Figures 1 and 2.

Antennae shorter than the head diagonal, measuring 100 µm and 120 µm, respectively; antennal segment IV with trilobed apical vesicle, subapical organite present, one lateral microsensillum, five subcylindrical sensillae, ventral side with shorter setae; sensory organ of antennal segment III formed by two oval microsensilla in a thin tegument fold, two guard sensilla with different shape and size: a ventral one, subcylindrical, and a dorsal one, smaller, thicker and curved ( Fig. 3); one microsensillum at ventral side; antennal segments I and II with seven and twelve setae, respectively ( Figs. 4 and 5).

Without eyes; postantennal organ formed by nine to eleven vesicles arranged in ellipse, measuring 20 µm ( Fig. 6). Maxilla globular, with seven teeth, maxillar head of 20 µm ( Fig. 7). Labial chaetotaxy as in Figure 8. Labral quetotaxy: 2/2334.

Tibiotarsi I, II and III with 18, 18 and 17 setae, respectively, without clavate tenent hair, seta M absent. Unguis measuring 30 µm, with one tooth at the inner lamellae and one pair of teeth at the lateral lamellae ( Fig. 9).

Ventral tube with 3+3 setae ( Fig. 10). Tenaculum with 2+2 teeth. Furca short, manubrium with 16 setae; dens measuring 15 µm, with 3+3 setae and a straight mucro, with its apex slightly curved ( Figs. 11 and 12). Female genital plate with seven setae, including two smaller setae placed near the genital furrow and five distal ones arranged in a semicircle. Each even anal valve with 2 setae hr ( Fig. 13).

Type Locality: National Park of Tijuca , Rio de Janeiro city, Rio de Janeiro state, Brazil. Found on soil and rotten log .

Type material: Brazil: Rio de Janeiro state: Rio de Janeiro city, National Park of Tijuca : female holotype on slide Nº 1212 CM / MNRJ, 19­IX­2002 , M. C. Mendonça col.; one paratype on slide Nº 183 CM / MNRJ, 24­VII­1986 ; five paratypes on slide Nº 819 CM / MNRJ ; one paratype on slide Nº 820 CM / MNRJ ; one paratype on slide Nº 821 CM / MNRJ, 22­VII­1999 ; three paratypes on slide Nº 852 CM / MNRJ, 25­VIII­1999 ; three paratypes on slide Nº 876 CM / MNRJ, 23­IX­1999 ; one paratype on slide Nº 1214 CM / MNRJ, 19­IX­2002 .

Other Examined Material: Brazil: São Paulo state: National Park of Serra da Bocaina , found in soil near stream, 1,300 m alt., 01­I­1989, S. Jesus col.: 18 specimens in Nº 269 CM / MNRJ and two specimens in Nº 270 CM / MNRJ .

Discussion: Folsomiella trisetosa sp. nov. is similar to F. albida ( Arlé, 1959) as both present similar general shape and apical structure of antennal segment IV, a postantennal organ and a complete, albeit reduced, furca. However, F. trisetosa , bearing three setae at the dens and 2+2 teeth at the tenaculum, is clearly separated from F. albida , with five setae at the dens and 3+3 teeth at the tenaculum. The new species is also distinguished from F. albida due to its very peculiar sensory organ of antennal segment III, composed by two oval microsensilla, protected by two sensilla of different shape and size (one ventral sensillum, subcylindrical, and one dorsal sensillum, smaller, thicker and curved). In F. albida , the two microsensilla are rounded and the two guard sensilla are subcylindrical. Besides, F. trisetosa sp. nov. has only thin and smooth setae, whereas F. albida has ciliated setae, with their apexes slightly expanded, from the abdominal tergite IV on. A careful comparison was made of the specimens of F. trisetosa collected at Bocaina with those from Tijuca. Almost all observed characters were identical, although a few ones varied between both populations. Bocaina specimens have the apical organ of antennal segment IV trilobed, whereas the apical organ of Tijuca specimens has only one lobe. Also, Tijuca specimens have a dens + mucro with half the length of that from Bocaina specimens.

Derivatio nominis: The species is named upon the presence of three setae at the dens.