Cuacuba, Prete, Pedro H., Cizauskas, Igor & Brescovit, Antonio D., 2018

Prete, Pedro H., Cizauskas, Igor & Brescovit, Antonio D., 2018, Three new species of the spider genus Plato and the new genus Cuacuba from caves of the states of Para and Minas Gerais, Brazil (Araneae, Theridiosomatidae), ZooKeys 753, pp. 107-162 : 137-138

Cuacuba gen. n.

Type species.

Cuacuba mariana sp. n.

Etymology.

The generic name " Cuacuba " means hidden in the native language of the South American indigenous tribe Tupi. It refers to the embolus of the male palp.

Monophyly.

This genus has at least three putative synapomorphies: C-shaped conductor with a posterior apophysis covering the embolus (Fig. 11 C–E), anterior apophysis with filamentous structures (Fig. 9D), and cuneiform tegulum (Fig. 9B).

Diagnosis.

Males of Cuacuba gen. n. can be distinguished from the other males in the family by the C-shaped conductor, split into anterior and posterior apophysis (Fig. 9 B–C). The anterior apophysis has distal filamentous ornaments (Figs 9D, 14E) and the posterior one covers the embolus (Figs 9B, 11 C–E). Resembles the genus Sinoalaria Zhao & Li, 2012 in the morphology of the conductor covering the embolus and in not having an embolic division (see Lin et al. 2014: fig. 6A). Females of Cuacuba gen. n. are similar to females of Sinoalaria in the curves of the copulatory ducts, and in position and shape of spermathecae (see Lin et al. 2014: figs 10 A–B), but can be distinguished by the lack of scapus, and by having epigynum with salient posterior margin, distally notched in the transversal groove (Figs 10B, 15 C–D).

Description.

Total length 1.3-3 mm. Cephalothorax longer than wide, thoracic groove inconspicuous. Clypeus 3 times AME diameter. Eyes: anterior row recurved, posterior row straight. PME separated by its diameter. Sternum: rounded posteriorly. Legs long, formula: 1243. Tibia with a single row of 4-5 trichobothria, relatively short when compared to other genera (not as short as in Wendilgarda ) (Fig. 7D). Tarsi with three claws. Paired claws with approximately five teeth. Unpaired claw long (Fig. 7E). Abdomen ovoid, larger than wide, with disperse and short bristles. Colulus a single flattened plate with a pair of bristles (Fig. 8D). Six spinnerets. Anterior lateral spinnerets larger than posterior lateral ones. Posterior median spinnerets smaller than others (Fig. 8C, E, F). Male palp with rounded cymbium (Fig. 9 A–B). Paracymbium wing-shaped (Fig. 9F). Subtegulum transparent over fundus (Fig. 11D). Tegulum massive, scaled, and cuneiform, almost half the size of the bulb (Fig. 11C). Median apophysis large, conical, with dark tip (Figs 11D, 14F). Conductor C-shaped with posterior apophysis large, covering the embolus, and anterior apophysis narrow, generally with ornament-like accessory structures on the tip (Fig. 11C). Embolus long, flageliform, with large base, pars pendula, mesal embolic apophysis (Fig. 12 A–B), and filamentous distal tip. Embolus covered by conductor up to the embolic opening (Fig. 12D), showing only tip of the embolus (Figs 11 D–E, 14 F–H). Female with epigynal plate sclerotized, without central pit, covered by short bristles, posterior margin triangular or rounded, distally notched (Figs 13A, 15A). Internally with long and coiled copulatory ducts, distally sclerotized, inserts laterally into the spermathecae, basal area with glandular ducts (Figs 13 C–D, 15B, E). Two basal oval and connate spermathecae, longer than fertilization ducts (Figs 13 C–D, 15B, D, E).

Natural history.

Cuacuba gen. n. was found only in caves. The species is a troglophile, as its specimens do not lack pigmentation nor have modified eyes (Fig. 3F).