Isotomiella macedoi, Mendonca, Maria Cleide de, Abrantes, Eduardo A. & Neves, Ana Carolina R., 2012

Mendonca, Maria Cleide de, Abrantes, Eduardo A. & Neves, Ana Carolina R., 2012, New species of Isotomiella Bagnall, 1939 from Southeast of Brazil (Collembola, Isotomidae), ZooKeys 233, pp. 21-30 : 22-25

Isotomiella macedoi sp. n. Figs 113

Material.

Holotype: Male (2320 CM/MNRJ): Southeast Brazil, State of Rio de Janeiro, Teresópolis municipality, Rain forest litter at 1.400 meters a.s.l., 14-III-2012. Mendonça, M.C. leg. One Paratype male, same data as holotype, One male and 12 Paratypes female (2364CM/MNRJ) Same locality of holotype. 31-V-2012. All material deposited in Collembola Collection of Museu Nacional da Universidade Federal do Rio de Janeiro (Brazil).

Description.

Total body length of the holotype 0,74 mm. Habitus typical of the genus. Color white. Integument without craters. Pseudopores and integument channels not observed.

Antennae subequal to head diagonal. Length of Ant I to IV (30 µm, 40 µm, 40 µm, 65 µm). Ant IV with one conspicuous tulip-shaped microsensillum with three or four small spines at apex protected by a curved chaeta, six broad and subequal sensilla, eight supplementary very thin sensilla (seven dorsal external, six dorsal internal and one shorter and thicker dorsal). Ant III with about 35-40 ordinary chaetae, two small sensory rods (3 µm), three guard sensilla (7 µm) and one short sensillum below (Fig. 1). Ant II with about 40 smooth ordinary chaetae, 2 basal microsensilla, one dorsal and one ventral, and one dorso-lateral sensillum (Fig. 2). Ant I with 14 smooth ordinary chaetae, two lateral ciliated chaetae, two ventral and unequal sensilla (10 µm and 4 µm) and two basal microsensilla, one dorsal and one ventral. Labral chaetae pattern 4 /5,5,4, the third row with two lateral acuminate chaetae and the last row with two anterolateral chaetae strongly thickened (Fig. 3). External lobe of maxilla with bifurcate palp and four sublobal chaetae (Fig. 4). All chaetae of head smooth. Axial chaetotaxy pattern from Th II to Abd IV as 20,14/6,6,6,6 by half tergite. Th II with 1+1 lateral ciliated macrochaetae (45 µm) and 3+3 lateral sensilla (5 µm). Th III with 1+1 lateral ciliated macrochaetae (50 µm) and 2+2 lateral sensilla (5 µm); all the other chaetae smooth (Fig. 5). Abd I with 1+1 lateral ciliated macrochaetae (40 µm) and 2+2 ciliated chaetae (30 µm) between the lateral macrochaetae; sensilla absent. Abd II with 1+1 lateral ciliated macrochaetae (40 µm) and 2+2 ciliated chaetae between lateral macrochaetae; sensilla absent and without the lateral area devoid of chaetae. Abd III with 2+2 anterior ciliated chaetae (35 µm) and 2+2 posterior ciliated chaetae (35 µm) between the lateral ciliated macrochaetae (40 µm), 1+1 ventral sensillum (5 µm). Abd IV with many ciliated chaetae (35-50 µm) and few smooth chaetae, 3+3 posterior sensilla (11 µm). Abd V-VI with several ciliated macrochaetae of different sizes (60-75 µm) and few smooth chaetae, 1+1 long and thick dorso-lateral sensillum (spl) with apex slightly curved (20 µm), 3+3 dorso-lateral sensilla sa, spe, spi (11 µm) and 1+1 ventral sensillum sv (5 µm) (Fig. 6). Dorso-lateral sensillary pattern of the body 3,2/0,0,1,2,5 (Fig. 7) Subcoxa I of legs I, II, III with 2, 3, 2 ciliated chaetae. Femur III with tenent hair smooth and two ciliated chaetae (Fig. 8). Tibiotarsus III strongly thickened on males, with about 40 smooth chaetae and 2 thin erect stick-like chaetae (10 µm); on females the tibiotarsus III are normal without stick-like chaetae. Unguis plump (20 µm) and unguiculus (10 µm) lanceolated (Fig. 9). Ventral tube (45 µm) with 4+4 anterior, 2+2 posterior and 4+4 distal chaetae (Fig. 10). Tenaculum with 4+4 teeth and 1 chaeta. Subcoxae anterior with 15 chaetae of which one ciliated; subcoxae posterior with 9 chaetae of which 6 ciliated (Fig. 11). Manubrium (55 µm) with 5+5 ventro-distal, 4+4 lateral, and 12+12 dorsal smooth chaetae. Dens long, (125-130 µm) crenulated, with about 40 anterior and 6 posterior smooth chaetae. Mucro small (7 µm), tridentate, the 2 basal teeth symmetrical (Fig. 11-12). Male genital plate as in Fig. 13.

Remarks.

Isotomiella macedoi sp. n. is easily included in the minor group sensu Kovác and Palacios-Vargas (2008) by its sensillar pattern (3,2/0,0,1,3,5), 3+3 to 5+5 ventral chaetae of manubrium, mucro tridentate and 4 sublobal chaetae. However, the new species also shares some characters, which do not define groups, with species of the nummulifer groups. With Isotomiella delamarei Barra, 1968, Isotomiella spinifer Deharveng & Oliveira, 1990, Isotomiella edaphica Bedos & Deharveng, 1994, Isotomiella leksawasdii Bedos & Deharveng, 1994, Isotomiella canina Mendonça & Fernandes, 2003, the new species shares the antero-lateral chaetae of labrum strongly thickened and blunt. With Isotomiella digitata Deharveng & Oliveira, 1990, I. distincta Mendonça & Fernandes, 2003 and Isotomiella falcata Mendonça & Fernandes, 2003, it shares the tibiotarsus III thickened. However the presence of a set of rare characters, in particular the tibiotarsus III strongly thickened with two thin erected stick-like chaetae in the males makes Isotomiella macedoi sp. n. unique among the genus Isotomiella . Females exhibit same characters as males, except this modified tibiotarsus III and stick-like chaetae.

Name derivation.

The species is dedicated to the husband of the senior author, Prof. Antonio Carlos M. Macedo, micropaleontologist.