Nanoa, Hormiga & Buckle & Scharff, 2005

Hormiga, Gustavo, Buckle, Donald J. & Scharff, Nikolaj, 2005, Nanoa, an enigmatic new genus of pimoid spiders from western North America (Pimoidae, Araneae), Zoological Journal of the Linnean Society 145 (2), pp. 249-262 : 252-254

NANOA GEN. NOV.

Type species: Nanoa enana .

Etymology: Derived from the Greek word nanos (dwarf), in reference to their small body size. The ending - oa follows that of Pimoa . Chamberlin & Ivie (1943) first used this ending for linyphioids with Pimoa . Although Chamberlin did not disclose the etymology of Pimoa, Prof. H. Don Cameron (University of Michigan) has deciphered its origin. Pimoa is a name derived from the language of the Gosiute people from Utah, and means ‘big legs.’ Nanoa matches the ending of the other two pimoid genera ( Pimoa and Weintrauboa ) and is feminine in gender.

Diagnosis: Nanoa differs from other pimoid genera by the following combination of characters: metatarsus– tarsus joint with a distinct constriction; male palpal tibia with dorsal process; dorsoectal cymbial process with a large and thick bent macroseta; alveolar sclerite on the ventral side of the cymbium, seen as a sclerotized spot on the ectal margin of the alveolus; pimoid embolic process absent ( Figs 1A–D , 2A–B ); cheliceral stridulatory striae absent; fourth coxae of male with two strong macrosetae, facing relatively large striated booklung covers ( Fig. 3A ); epigynum with a ventral scape-like septum and fertilization ducts posteriorly orientated ( Fig. 3C–E ). PMS and PLS without aciniform spigots; PMS minor ampullate spigot absent ( Fig. 5D–E ).

Description: Since the genus is monotypic, the description is given under Nanoa enana .

Phylogenetics: Nanoa is sister to Pimoa . In the present cladistic analysis the terminal branch leading to Nanoa is the longest one in the cladogram ( Fig. 7 ) as a consequence of the highly modified morphology of this genus (despite the fact that many autapomorphic features were not coded in the matrix).

Natural history: Unknown.

Composition: One species, Nanoa enana sp. nov.

Figures

Figure 1. Nanoa enana sp. nov., male palp (embolus in a slightly displaced position; normally its distal end rests tightly against the tegulum, next to the conductor). A, ventral; B, dorsoectal (arrow points out to homologue of alveolar sclerite); C, mesal; D, ectal. Scale bars = 0.1 mm. See main text for abbreviations.

Figure 2. Nanoa enana sp. nov. A–B, male palp, schematic drawings. A, ventral; B, dorsoectal (arrow points out the homologue of alveolar sclerite, seen by transparency through the cymbial cuticle). See main text for abbreviations.

Figure 3. Nanoa enana sp. nov. A, male, ventral; B, female, dorsal; C, epigynum, ventral; D, cleared epigynum, ventral (arrow points out to possible location of copulatory opening); E, cleared epigynum, dorsal (arrow points out to distal end of fertilization duct). Scale bars: A, B = 0.5 mm; C–E = 0.1 mm. See main text for abbreviations.

Figure 5. Nanoa enana sp. nov. Female. A, epigynum, ventral; B, epigynum, caudoventral; C, epigynum, caudal; D, partially damaged PLS and PMS (PMS cylindrical spigot has shaft broken off; left PLS, on right, has one cylindrical spigot and part of the triplet broken off); E, right PLS triplet with ectal cylindrical spigot; F, prosoma, lateral. See main text for abbreviations.

Figure 7. One of the eight minimal length trees of 188 steps that result from the analysis of the data matrix presented in the Appendix (CI = 0.53, RI = 0.73). Exclusion of the six parsimony uninformative characters decreases the tree length to 179 steps and the ensemble consistency index to 0.51. Most of the ambiguous character changes are resolved under ‘Farris optimization.’ Closed circles represent nonhomoplasious character changes. The three nodes that collapse in the strict consensus cladogram of the eight most parsimonious trees (Fig. 6) are marked with a closed rectangle. The basal trichotomy has been resolved according to the araneoid topology presented in Griswold et al. (1998) (see text for details).