Alboscia itapuensis, Araujo & Quadros, 2005

Araujo, Paula Beatriz & Quadros, Aline Ferreira, 2005, A new species of Alboscia Schultz, 1995 (Crustacea: Isopoda: Oniscidea: Philosciidae) from Brazil, Zootaxa 1018 (1), pp. 55-60 : 56-57

Alboscia itapuensis n. sp. ( Figs. 1–20 )

Material: Holotype: ♂, BRAZIL, Rio Grande do Sul, Viamão, 30°34’S, 51°05’W, Parque Estadual de Itapuã, Trilha da Onça , sifting soil, 23 June 2004 ( MZUSP 16252 ) . Paratypes, same locality as holotype, 24 August 2004, 2 ♀ ( UFRGS 3791 ) ; same locality, 21 August 2004, 1 ♂ and 1 ♀ ( UFRGS 3792 ) .

Description: Maximum dimensions: male 2.0 x 0.5 mm; ovigerous female 2.8 x 0.9 mm. Body lacking pigment; eyes absent. Body surface smooth with long setae. Conspicuous noduli laterales (coordinates b/c and d/c as in Fig. 2 ; “d” shows similar distance in all pereonites). Pleon slightly retracted from pereon ( Fig. 1 ). Epimera of pleonites not visible in dorsal view. Pleotelson with rounded apex and sinuous lateral margins, bordered by long setae, about 4 times as wide as long ( Fig. 8 ).

Antennule slender with distal article bearing 1 sub­apical and 2 apical aesthetascs ( Fig. 3 ). Antenna, when extended posteriorly reaches pereonite II; distal flagellar article longest, bearing 2 aesthetascs; apical organ as long as the first flagellar article ( Fig. 4 ). Mandibles with 1 and 2 penicils on the right and left mandibles respectively. Inner lobe of the maxillule with rounded apical margin, bearing two penicils; outer lobe with 4+5 teeth (3 pectinate and 1 bifid) ( Fig. 5 ). Maxilla covered with short hair­like setae on the internal lobe ( Fig. 6 ). Palp of maxilliped conical, without apical setal tuft; medial tufts composed of 2 and 1 seta; endite with a medial seta and one spine on curved margin ( Fig. 7 ). Pereopods with spoon­like dactylar organ and 2 ungual setae (except in pereopod 1, in both male and female); no sexual dimorphism on pereopods ( Figs. 9­12 ). Exopod and endopod of the uropod with a single apical seta ( Fig. 8 ).

Genital papilla with ventral shield pyriform and rectangular spatula ( Fig. 13 ). Pleopod 1 exopod oval and without setae ( Fig.14 ); endopod moderately curved apically with one small apical spine ( Fig. 15 ). Pleopod 2 exopod subtriangular, with 3 setae on the external lateral margin ( Fig. 16 ); endopod with slender distal half and small medial setae ( Fig. 17 ). Pleopods 3–5 with exopods presenting posterolateral margin with long setae ( Figs. 18–20 ).

Etymology: The specific name refers to the type locality: Itapuã.

Remarks: Alboscia itapuensis n. sp. resembles A. silveirensis with respect to the length of flagellar articles and apical organ of the antenna, maxillule with three pectinate teeth and one bifid, presence of two ungual setae as well as the shape of the exopod of pleopod 1 of the male. The new species can be readily distinguished from A. elongata , A. silveirensis and A. ornata by the absence of eyes, the pattern of the aesthetascs on the antennule, the telson being posteriorly rounded and four times as wide as long and by the spoon­like dactylar organ. This is the first known eyeless species of Alboscia .

Alboscia itapuensis n. sp. is an endogean species found under the litter layer, in soft soil, at depth of about 2 cm.

All species of Alboscia , including A. itapuensis n. sp., have a depigmented body and either lack eyes or have a reduced number (1–3) of ommatidia.

Figures

FIGURES 1–7. Alboscia itapuensis n. sp. Male: 1, dorsal view; 2, coordinates b/c and d/c of noduli laterales; 3, antennule; 4, antenna; 5, maxillule; 6, maxilla; 7, maxilliped. Scales (1) = 1 mm; (3) = 0.05 mm; (4–7) = 0.1 mm.

FIGURES 8–12. Alboscia itapuensis n. sp. Male: 8, telson and uropods; 9, pereopod 1; 10, pereopod 7; 11, pereopod 2, dactylus; 12, pereopod 6, dactylus. Scales (8, 9, 10) = 0.1 mm; (11, 12) = 0.05 mm.

FIGURES 13–20. Alboscia itapuensis n. sp. Male: 13, genital papilla; 14, pleopod 1 exopod; 15, pleopod 1 endopod; 16, pleopod 2 exopod; 17, pleopod 2 endopod; 18, pleopod 3 exopod; 19, pleopod 4 exopod; 20, pleopod 5 exopod. Scales = 0.1 mm.