Arenita fazendinha Huber & Carvalho, 2019

Huber, Bernhard A. & Carvalho, Leonardo S., 2019, Filling the gaps: descriptions of unnamed species included in the latest molecular phylogeny of Pholcidae (Araneae), Zootaxa 4546 (1), pp. 1-96 : 50-51

Arenita fazendinha Huber & Carvalho sp. n.

Figs 177–188 , 192–197

Gen.n. Br16-44: Eberle et al. 2018 (molecular data); Huber et al. 2018: fig. 3.

Type material. BRAZIL: ♂ holotype, UFMG (22738) ; 3♂ 4♀ paratypes, UFMG (22739, 22616), 5♂ 2♀ paratypes, CHNUFPI (2533), and 4♂ 12♀ 2 juvs paratypes, ZFMK (Ar 20631), Amapá, forest SW Macapá, Área de Proteção Ambiental da Fazendinha , ‘site 2’ (0.051°S, 51.123°W), 20 m a.s.l., 12.x.2016 (B.A. Huber, L.S. Carvalho) .

Other material examined. BRAZIL: 3♀, CHNUFPI (2540, 2547, 2552) ; 1♂ 2♀, UFMG (22612, 22620, 22623); and 2♀ 2 juvs, ZFMK (Br16-252), all in pure ethanol, same data as types .

Etymology. The species name is derived from the type locality; noun in apposition.

Diagnosis. Males are easily distinguished from all other known pholcids by highly distinctive macroseta on male palpal trochanter ( Figs 185–186 ), by shapes of male palpal segments ( Figs 185–186 ; femur small, patella globular, tibia large), by procursus reduced to tiny transparent projection ( Fig. 186 ); from most known pholcids also by barely modified male chelicerae ( Fig. 187 ; only pair of indistinct lateral humps proximally); females are distinguished by combination of small size, eight eyes, oval epigynum with anterior and posterior epigynal plates of approximately same size ( Fig. 182 ). Males and females are apparently unique among known Pholcidae by presence of only one trichobothrium on each palpal tibia ( Figs 186 , 196 ).

Description. Male (holotype). MEASUREMENTS. Total length 0.93, carapace width 0.40. Distance PME-PME 40 µm; diameter PME 35 µm; distance PME-ALE 10 µm; distance AME-AME 15 µm, diameter AME 20 µm. Leg 1: 2.16 (0.63 + 0.13 + 0.55 + 0.52 + 0.33), tibia 2: 0.47, tibia 3: 0.40, tibia 4: 0.57; tibia 1 L/d: 11.

COLOR (in ethanol). Prosoma and legs ochre-yellow, abdomen monochromous ochre-gray.

BODY. Habitus as in Figs 177–178, 180–181 . Ocular area barely elevated. Thoracic furrow absent (cf. female, Fig. 192 ). Clypeus unmodified. Sternum slightly wider than long (0.28/0.26), unmodified. ALS with one widened, one pointed and several (approx. five) long cylindrically shaped spigots ( Fig. 193 ). Gonopore without epiandrous spigots ( Fig. 195 ).

CHELICERAE. As in Fig. 187 , barely modified, with pair of indistinct lateral humps proximally.

PALPS. As in Figs 185–186 ; coxa without retrolateral apophysis, trochanter with highly distinctive macroseta, femur with retrolateral process proximally and short ventral process with two hairs; patella globular; tibia with only one trichobothrium (retrolateral trichobothrium absent; confirmed in other males); procursus tiny and weakly sclerotized, barely visible in dissecting microscope; bulb large and complex.

LEGS. Without spines and curved hairs, few vertical hairs; retrolateral trichobothrium of tibia 1 at 51%; tibia 1 without prolateral trichobothrium (present on other tibiae); tarsus 1 with 6 pseudosegments, fairly distinct.

Male (variation). Tibia 1 in 15 males (incl. holotype): 0.55–0.69 (mean 0.59).

Female. In general similar to male ( Fig. 179 ). Tibia 1 in 22 females: 0.41–0.51 (mean 0.47). Palpal tibia with only one trichobothrium ( Fig. 196 ); palpal tarsal organ exposed ( Fig. 197 ). Epigynum very simple externally ( Fig. 182 ), anterior and posterior plates of approximately same size, central area whitish, internal sclerotized arc visible through cuticle. Internal genitalia very short relative to epigynal plate ( Figs 183–184 , 188 ), presence of pore plates not unambiguously confirmed (possibly in vertical position). ALS spigots as in male ( Fig. 194 ).

Distribution. Known from type locality only ( Fig. 345 ).

Natural history. This species was found in relatively dry leaf litter in a slightly elevated part of a daily flooded forest. When shaken on a white sheet of plastic, the spiders ran away very quickly.

Figures

FIGURE 345. Type localities of the type species of four monotypic genera newly described herein.

FIGURES 177–184. Arenita fazendinha sp. n. (ZFMK, Ar 20631). 177–179. Live males and female with egg sac. 180–181. Male, dorsal and lateral views. 182. Epigynum, ventral view. 183–184. Cleared female genitalia, ventral and dorsal views. Scale lines: 0.5 (180–181), 0.2 (182–184).

FIGURES 185–186. Arenita fazendinha sp. n. (ZFMK, Ar 20631). Left male palp, prolateral and retrolateral views. gb, genital bulb; pr, procursus; tr, trochanter. Scale line: 0.2.

FIGURES 187–188. Arenita fazendinha sp. n. (ZFMK, Ar 20631), male chelicerae, frontal view, and cleared female genitalia, dorsal view. Scale lines: 0.1.

FIGURES 189–197. Chibchea amapa sp. n. (189–190, ZFMK, Ar 20627), C. santosi sp. n. (191, ZFMK, Ar 20628), and Arenita fazendinha sp. n. (192–197, ZFMK, Ar 20631). 189. Female palpal tibia; note presence of two trichobothria. 190. Epigynum, ventral view. 191. Female ALS. 192. Female prosoma. 193–194. Male and female ALS. 195. Male gonopore. 193. Female palpal tibia; note presence of only one trichobothrium. 197. Female palpal tarsal organ. Scale lines: 2 µm (193-194, 197), 10 µm (189, 191, 195–196), 100 µm (190, 192).