Avicularia rickwesti sp. nov., a remarkable new species of Avicularia (Theraphosidae: Aviculariinae) from Dominican Republic

A remarkable new species of Avicularia Lamarck, 1818, Avicularia rickwesti sp. nov., is described from Dominican Republic. Female specimens of the new species are unusual by having two very short and broad spermathecae with distal half strongly sclerotized, a feature not found in any other aviculariine. Additionally, it has the leg coxae with spiniform setae, smaller on leg I and prolateral leg II, larger, black on retrolateral leg II, prolateral and retrolateral leg III and prolateral leg IV. Males are unknown. The new species is known only from two localities, in southwestern Dominican Republic. This is the first record for the subfamily on Hispañola which is close to the northern boundary for the Aviculariinae distribution.


MATERIAL AND METHODS
All measurements are in millimeters and were obtained with a Mitutoyo digital caliper with an error of 0.005 mm, rounded up to two significant decimals. Leg and palp measurements were taken from the dorsal aspect of the left side (unless appendages were lost or obviously regenerated). A Leica LAS Montage and LAS 3D module mounted on a Leica M205C dissecting microscope were used for image capture of spider structures. Urticating hairs were examined with a Leica DM2500 compound microscope and images were captured with a Leica DFC450 digital camera. Abbreviations: (ALE) anterior lateral eyes, (AME) anterior median eyes, (ITC) inferior tarsal claw, (PLE) posterior lateral eyes, (PLS) posterior lateral spinnerets, (PME) posterior median eyes, (PMS) posterior median spinnerets, (STC) superior tarsal claws. Terminology of urticating hairs follows COOKE et al. (1972).
Specimens are deposited in the American Museum of Natural History, New York (AMNH) and Instituto Butantan, São Paulo (IBSP).
Variation. The paratype, a smaller specimen, has a straight fovea and less developed spiniform setae on the coxae.
Distribution. Only known from type localities (Fig. 15). Etymology. The specific name is a patronym in recognition of the contribution to taxonomy and biology of theraphosids done by Rick C. West.
Natural history. The holotype was found in a sparse deciduous forest of Acacia sp. and thorny scrub, with many limestone boulders (Figs 16 and 19). It was collected in a narrow tree hole in a small tree with approximately a 10 cm diameter trunk. A silken tube extended about 15 cm outside of the tree hole (Figs 17 and 18). Spiderlings were found with the female and were approximately 2-3 months old (Fig. 13). The paratype was collected in a very different habitat. It was a broad-leafed forest with no/little under story. The trees were very tall and it appears that A. rickwesti sp. nov. is found high in the canopy. The specimen was found on a recently fallen tree. A small female (carapace 8.1 long, 6.1 wide) from Jaragua National Park, Los Tres Charcos, collected in 20 February 2012, had and eggsac 8.8 in diameter, with 15 eggs probably infertile and one spiderling.

DISCUSSION
Avicularia rickwesti sp. nov. is remarkable for its highly modified genitalia, a paired spermathecae twice wider than long and strongly sclerotized at their distal half (Fig. 2). All other aviculariine species have paired spermathecae longer than wider and weakly sclerotized ( Fig. 1) (WEST et al. 2008, BERTANI 2012. The new species also has some spiniform setae on posterior leg coxae not found or weakly developed in other aviculariines (Figs 4 and 5). The abdomen has an oak leaf pattern  with resemblance in aviculariines only with Ephebopus foliatus West, Marshall, Fukushima & Bertani, 2008. All these apomorphic characteristics make A. rickwesti sp. nov. very distinct from other Avicularia species and its inclusion into this genus could be seen as inadequate at first glance. However, its inclusion in other aviculariine genera has no support, as the conjunt of characters completely aspinose legs, procurved first eye row (Fig. 7), digitiform distal article of the posterior lateral spinnerets (Fig. 9) and the presence of urticating hairs type II on abdomen dorsum (Figs 10 and 11) indicate the species should be included either into Avicularia or Iridopelma Pocock, 1901 genera. The inclusion in Iridopelma would be dubious since (2) Avicularia rickwesti sp. nov. holotype; (3-14) Avicularia rickwesti sp. nov.: (3-6) holotype: (3) leg coxa I, retrolateral; (4) leg coxa II, prolateral; (5) leg coxa III, retrolateral; (6) leg coxa IV, prolateral, showing area with spiniform setae; (7) paratype: cephalothorax, dorsal; (8-11) holotype: (8) maxillae, labium and sternum; (9) spinnerets; (10-11) type II urticating hair: (10) with stalk; (11) released from stalk. (12-14) habitus: (12) female unusual dark form; (13) early antepenultimate immature; (14) female usual brown form "in situ". Photos: 12-13 Jeremy Huff, 14 Rick West. Scale bars: 1-9 = 1 mm, 10-11 = 0.1 mm. Iridopelma is endemic to Brazil (BERTANI 2012). Furthemore, some biological features indicate a close relationship with other Avicularia species. Avicularia rickwesti sp. nov. builds a similar retreat as other Avicularia species in tree trunks instead of retreats made of leaves connected with silk made by Iridopelma specimens (BERTANI 2012). The discovery of a male would aid in giving support or rejecting the inclusion of the species in Avicularia, but the male remains unknown after three trips to the topotypical region. Therefore, we prefer to describe the species with females only and wait for the discovery of a male to confirm the present classification.