A new Pseudachorutes (Collembola, Neanuridae, Pseudachorutinae) from Nicaragua

Abstract A new species of Pseudachorutes is described and illustrated from Nicaragua. Pseudachorutes nica sp. n. is very easy to distinguish from other members of this genus from Central America, because its chaetotaxy consists of macro and microsetae and a postantennal organ with multiple vesicles (close to 20).

While studying the Collembola material from a project of the Centre de Recerca Ecologica i Aplicacions Forestals of Barcelona (CREAF) in Nicaragua, we found many specimens of a new species which is described herein.
Diagnosis. Postantennal organ with about 20 vesicles in an ellipse; ocular area, head, and body with setae of different size; Ant. IV with a well developed ventral sensorial file with 20-25 setae; one lateral teeth on each side of unguis, presence of setae d1 unpaired on head and m2 on Th. II. Abd. IV with three rows of setae, p1 longer than seta p2 and a1. No capitate tenent hairs on tibiotarsi.
Dorsal chaetotaxy as in Figs 6 and 8. Seta a0 on the head absent, unpaired seta d1 present. Th. I with 3+3 dorsal setae. Setae a2 present on Th. II, but absent from Th. III to Abd. IV, with m4 present on Abd. IV. Sensory setae on the body in position of p4 and m6 on Th. II and III, and p5 from Abd. I-IV and p3 on Abd. V. Sensorial formula of the body 022/11111. Sensory setae longer and slender than ordinary setae. Ratio of unguis III: largest Abd. V seta = 1: 0.5. Thoracic sterna without setae, but paratergal areas of Th. II and III with two setae on each side. Ventral tube with 4+4 setae, the posterior pair is longer than the others. Female genital plate with 3+3 pregenital, 7-12 circumgenital and 2 eugenital setae (Fig. 10); male genital plate with 3+3 pregenital, 10-13 circumgenital and 4+4 to 6+6 eugenital setae (Fig. 11). Each anal valve with 13 setae and 3 hr setae.
Furcula well developed. Manubrium with one pair of dorsal longer setae. Dens with moderate granulation dorsally and with 6 setae, with a smooth triangular area ventrally devoid of secondary granulation. Mucro about half the length of dens, triangular, with two very short lamellae and granulation similar to dens, apex slightly curved (Fig. 9). Tenaculum with 3+3 teeth.
Etymology. The name is derived from the country nickname that is the type locality. Distribution. Known only from type locality. Province Estelí: Mesas de Moropotente, Acacia pennatula, Oplinemus, Croton jalapensis forest, 23 August 2007, ex soil from pit fall traps.
Ecology. More than 135 specimens were found in the samples of pitfall traps from two different pasture fields on August 23, 2007. The species is very abundant in most of the collecting traps.
Discussion. Pseudachorutes nica sp. n. is easily distinguished from all other species of the genus by the combination of the following characters: presence of many vesicles in the postantennal organ, well-differentiated macrosetae and microsetae on dorsal side of head and body, one ventral sensorial file on Ant. IV, presence of one lateral tooth on each side of unguis, presence of setae d1 unpaired on the head and presence of setae m2 on Th. II. On Abd. IV p1 is longer than p2 and a1. The new species is close to P. orghidani Massoud and Gruia 1969, but differs in the number of teeth on the mandible (3 versus 4) and in the morphology of the apex of the maxilla (sharp versus hooked). Other similarities and differences among species from the Caribbean region are summarized in Table 1.
Variation. The number of vesicles of postantennal organ varies asymetrically from 14 to 20. The number of circumgenital setae on the male genital plate varies from 10 to 13 and that of eugenital setae from 4 + 4 to 6 + 6. Some of the adult specimens have macrosetae with blunt tips. table 1. Comparison of P. nica sp. n. with other Caribbean species (size in mm; Ant bulb = number of lobes in antennal apical bulb; Ant. IV = number of cylindrical sensilla; PAO = number of vesicles; PAO/E = size PAO/eye ratio; Md = number of mandibular teeth; Ocular = type of ocular setae 1, 2 and 3; Inner u = inner unguis teeth; LUT = lateral unguicular teeth); D = number of dental setae; TH = number of tenent hairs, ac = acuminate, cap = capitate.