Isotomodes fernandesae, Abrantes & Mendonça, 2007

Abrantes, Eduardo Assis & Mendonça, Maria Cleide De, 2007, New species and a new record of Isotomidae (Collembola) from the coast of Brazil, Zootaxa 1500 (1), pp. 55-60 : 57-58

Isotomodes fernandesae sp. nov.

Figs 11–17

Description. Habitus typical of the genus. Body length 0,59 mm – 0,98 mm. Without pigment. Integument minutely granulated.

Dorsal chaetotaxy of the head and the body as in Figs 11 and 12 .

Postantennal organ oval, with 8–9 setae along posterior margin (18 µm) shorter than the first antennal segment diameter ( Fig. 11 ). Antennae slightly longer than head; ratio antenna: head = 1: 1,4. Antennal segment IV with about 20 dorsal sensilla; one apical microsensillum and one small organ in a shallow depression ( Fig. 13 ). Antennal segment III with about 21 setae, sensory organ of antennal segment III oval, covered by an integumentary fold and protected by two guard sensilla; one short ventro-external sensillum. Antennal segment II with about 19 small acuminate setae; two basal microsetae, one dorsal and one ventral. Antennal segment I with about 11 setae; three basal microsetae, two dorsal and one ventral. Antennal segments ratio I: II: III: IV = 1: 1,32: 1,5: 2,14.

Axial dorsal chaetotaxy from thorax II to abdominal III as 8,6/4,4,5. Macrochaetotaxy: 1,1/1,1,1,1. Sensillar formula from thorax II to abdominal III (s + ms): 4,3/2,2,2. Abdominal segment IV with 1+1 dorsal lateral sensillum (14 µm) and 4 m-setae presents. Abdominal segment V with 4+4 dorsal microsetae and 1+1 dorsal lateral sensillum. Abdominal segment IV with p 1 and p 3 spiniform, short and denticulated (25–30 µm), p 2 and p 5 long and barbulated (55 µm), p 0 and p 4 smooth, 1+1 ventral sensillum ( Figs 14–15 ).

Tibiotarsi I, II and III with 23, 23, 25 setae respectively. Unguis unthoothed with strong lateral spine, unguiculus whit half size of unguis ( Fig. 16 ). Ventral tube (40 µm) with 4+4 distal and 2+2 posterior setae. Tenaculum with 4+4 teeth and one seta on corpus. Subcoxa furcalis anterior with four setae, posterior with three seta. Manubrium with 13 pairs of setae on posterior surface. Dens with two internal hooks, 2 long posterior setae, 6 short anterior setae. Mucro bidentate. Ratio manubrium: dens: mucro = 10,8: 4,1: 1 ( Fig. 17 ). Male genital opening with 3+3 lateral setae and one pair of anterior setae.

Type locality: Restinga de Maricá , Maricá city, Rio de Janeiro State, Brazil. Found in sand beach .

Type material: Brazil: Rio de Janeiro State: Maricá city, Restinga de Maricá , female holotype on slide Nº 1339 CM / MNRJ, 31.vii.2003 , L.H. Fernandes & E.A. Abrantes. coll.; two paratypes on slide N° 1259 CM / MNRJ, 28.i.2003 ; one paratype on slide N° 1279 CM / MNRJ, 28.i.2003 ; one paratype on slide N° 1280 CM / MNRJ, 28.i.2003 ; one paratype on slide N° 1282 CM / MNRJ, 28.i.2003 ; one paratype on slide N° 1283 CM / MNRJ, 28.i.2003 ; one paratype on slide N° 1365 CM / MNRJ, 31.vii.2003 ; one paratype on slide N° 1366 CM / MNRJ, 31.vii.2003 ; Brazil: Rio de Janeiro State, Rio de Janeiro city, Restinga da Marambaia , one paratype on slide Nº 1639 CM / MNRJ, 16.xii.2006 ; one paratype on slide Nº 1639 CM / MNRJ, 16.xii.2006 .

Discussion: The genus Isotomodes Linnaniemi, 1907 , world wide distributed, has 13 species known from the Neotropical Zone, but only two from Brazil: I. trisetosus Denis, 1923 (Amazon Rain Forest) and I. carioca Thibaud & Palacios-Vargas, 1999 (Maricá sand beach). The new species is clearly separated from those two by a series of characters. Isotomodes fernandesae sp.nov. is closest to the species I. bahiensis Rapoport, 1962 from Bahia Blanca, Argentina. Although the lack of information concerning the taxonomical characters of I. bahiensis species, such as dorsal chaetotaxy, its possible to separate both species by the number of microseta m on abdominal IV, 6 on I. bahiensis and 4 on Isotomodes fernandesae sp.nov. and the setae p 1, p 2, p 3, p 5 are barbulate in the new species, different from the smooth seta in I. bahiensis .

Derivatio nominis. This species is dedicated to Dr. Liliane Henriques Fernandes for their unconditional friendship and technical support.

Figures

FIGURES 11–17. Isotomodes fernandesae sp. nov.: 11, dorsal cephalic chaetotaxy; 12, dorsal chaetotaxy of tergites (dorsolateral view); 13, antennal segments III–IV (dorsolateral view); 14, abdominal segments V–VI (ventral view); 15, abdominal segments V–VI (dorsal view); 16, leg III; 17, subcoxa and furca.