Archisotoma catiae, 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 : 55-57

Archisotoma catiae sp. nov.

Figs 1 –10

Description. Habitus typical of the genus. Body length 0,49–0,55mm. Color grayish interspersed with pale spots. Tegumentary granulation very fine. Body setae short and simple.

Dorsal chaetotaxy of the head and the body with thin, short and simple setae as show in Figs 1 and 2 .

Antennae ( Fig. 3 ) slightly shorter than head; ratio antenna: head = 117µm: 118µm. Ant. IV with 12 dorsal sensilla (11 µm), one lateral microsensillum and sub apical organ present ( Fig.4 ). Ant. III with about 39 setae and 1 ventral microsensillum. Ant II with about 22 setae and 2 basal microsetae, 1 ventral and 1 dorsal. Ant. I with about 15 setae and 1 basal microseta. Antennal segments ratio I:II:III:IV = 1:1,4:1,9:2,3.

Eyes 6+6 and long darkly eye patch area. Postantennal organ oval, about 3 times as long as diameter eye and surrounded by 5 setae ( Fig. 1 ). Labrum with 5,5,4 setae and 2 prelabral setae; clypeal setae not studied. Maxillary capitulum complex, long and slender, unidentate equal size of the internal lamellae; three maxillary lamellae the ventral external and ventral internal with fringes ( Fig. 5 ); molar plate as in figure 6.

Axial dorsal chaetotaxy from thorax II to abdominal III as 7,5/3,3,3. The sensilla in thoracic segments are indistinct from the common setae. Abdominal segment IV with 3 axial anterior unpaired setae and 2+2 axial posterior paired setae. Abdominal segment V with 3+3 axial setae and abdominal segment VI with 5 unpaired setae ( Fig. 7 ). Abdominal VI with 2+2 trichobothria thin and smooth, the first pair longer (35 µm) than the second pair (15 µm), separated by 3 setae from the first pair.

Tibitarsi I, II and III contains 22,25,26 setae respectively (In Holotype). Tibiotarsus III with thick apical spur (6µm). Unguis untoothed (12µm); empodial appendage short and lanceolated about half the unguis length ( Fig. 8 ). Ventral tube with 4+4 laterodistal setae ( Fig. 9 ). Tenaculum with 4+4 teeth and one seta on corpus. Subcoxa furcalis: anterior with about 16 setae and posterior with about 13 setae. Manubrium with 23 setae on anterior surface and no posterior setae. Dens with 9 setae on anterior side setae and 9 setae on posterior side. Mucro with three asymmetrical teeth, the apical tooth bigger than the others, with basal setae. Ratio of manubrium:dens:mucro = 4,9:4,2:1 ( Fig. 10 ).

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

Type material. Brazil: Rio de Janeiro State: Maricá city, Restinga de Maricá , male holotype on slide Nº 1320 CM / MNRJ, 25.vi.2003 , L.H. Fernandes & E.A. Abrantes, coll.; three paratypes on slide Nº 1314 CM / MNRJ, 25.vi.2003 ; two paratypes on slide Nº1320 CM / MNRJ, 25.vi.2003 ; two paratypes on slide Nº1320 CM / MNRJ, 25.vi.2003 ; three paratypes on slide Nº 1259 CM / MNRJ, 31.vii.2003 ; one paratype on slide Nº 1260 CM / MNRJ, 31.vii.2003 .

Discussion. Archisotoma catiae sp. nov. belongs to the besselsi group, which is represented by 11 species and characterized in according to Potapov (2001) by small size, tibiotarsi III with stiff outer spur, maxillary head with thin simple capitulum, 3–2 pairs of trichobothria on abdominal segment VI. Archisotoma catiae sp.nov. shows a variable number of setae in tibiotarsi I, II and III with the variation includes species with 22, 23, 22 to 23, 29, 27 setae respectively. The new species is closest to A. vaoensis Thibaud & Weiner, 1997 described from New Caledonia by the number of prelabral setae, the dens chaetotaxy and the number of setae between the anterior trichobothria. Archisotoma catiae sp.nov. can be distinguished by the number of setae in tibiotarsus I, II and III, the body chaetotaxy and the size of maxillary capitulum. In A. vaoensis the number of setae in tibiotarsus I, II and III: 23, 28, 28; the axial chaetotaxy from thorax II to abdominal I: 8,5/4 ( Thibaud & Weiner 1997); the maxillary capitulum is reduced, as half size of the internal lamellae (Thibaud & Palacios- Vargas 2001), but in the new species the number of setae in the tibiotarsus I, II and III is variable, the axial chaetotaxy from thorax II to abdominal III is 7,5/3,3,3 and the size of the maxillary capitulum is equal of the internal lamellae.

Derivatio nominis. This species is dedicated to our great friend Dr. Cátia Antunes Mello-Patiu.

Figures

FIGURES 1–10. Archisotoma catiae sp. nov.: 1, dorsal cephalic chaetotaxy; 2, dorsal chaetotaxy of tergites, dorsolateral view; 3, antennal segments; 4, apical organ of the antennal segment IV; 5, maxillae; 6, mandibulae; 7, abdominal segments V–VI; 8, leg III; 9, ventral tube; 10, subcoxa and furca.