Psilochorus bromelicolus Huber, 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 : 64-67

Psilochorus bromelicolus Huber sp. n.

Figs 240–251

Psilochorus Br 11-40: Eberle et al. 2018 (molecular data); Huber et al. 2018: fig. 3.

Type material. BRAZIL: ♂ holotype , 1♀ paratype, MNRJ (14324–25), and 3♂ 7♀ paratypes, ZFMK (Ar 20647), Bahia, Camacan, Reserva Particular do Patrimônio Nacional Serra Bonita (15°23.3’–23.4’S, 39°33.7’–34.0’W), ~ 750–850 m a.s.l., 2–3.x.2011 (B.A. Huber, A. Pérez González, M. Alves Dias) .

Other material examined. BRAZIL: 1♂ 6♀ 2 juvs in pure ethanol, ZFMK (Br11-162a), same data as holotype .

Etymology. The species name is an adjective and refers to the microhabitat in which this species was found (see below).

Diagnosis. Males are easily distinguished from all other known pholcids by armature of male chelicerae ( Figs 249–250 ): proximal frontal processes with dense brushes of hairs with short but strong side branches; also by shape of procursus ( Figs 246, 248 ): very simple, distally weakly sclerotized and curved towards prolateral. The ZFMK has a very similar undescribed species with much smaller but otherwise identical pedipalps (femur length 0.26– 0.28 versus 0.40), shorter cheliceral apophyses, and longer and thinner legs (tibia 1 L/d 85 versus 55). Females of P. itaguyrussu and P. ybytyriguara are unknown; females of undescribed species in ZFMK differ by shape of epigynum (compare Figs 243–245 with 252–263).

Description. Male (holotype). MEASUREMENTS. Total length 3.5, carapace width 0.95. Distance PME-PME 50 µm; diameter PME 110 µm; distance PME-ALE 70 µm; distance AME-AME 10 µm, diameter AME 15 µm. Leg 1: 18.0 (4.2 + 0.3 + 4.4 + 7.7 + 1.4), tibia 2: 2.8, tibia 3: 2.1, tibia 4: 2.7; tibia 1 L/d: 55.

COLOR (in ethanol). Carapace pale ochre with brown median band including ocular area and brown lateral bands; clypeus brown; sternum light brown with some light spots; legs light brown with darker rings on femora (subdistal) and tibiae (proximal and subdistal). Abdomen pale greenish, with bluish marks dorsally and laterally; ventrally with light brown plate in front of gonopore and dark median band behind gonopore.

BODY. Habitus as in Figs 241–242 . Ocular area slightly raised. Thoracic furrow shallow but distinct in anterior part. Clypeus unmodified. Sternum wider than long (0.60/0.46), unmodified. Gonopore in very posterior position (at ~70% of abdomen length).

CHELICERAE. As in Figs 249–250 , with distinctive pair of frontal apophyses curved downwards and set with dense brushes of hairs with short but strong side branches.

PALPS. As in Figs 246–248 ; coxa relatively large (i.e. palp small relative to body size), with rounded retrolateral apophysis, trochanter barely modified, femur with retrolateral-ventral process proximally and distinct ventral apophysis distally; tarsus with 3–4 macrosetae; procursus simple, distally weakly sclerotized, widened, and curved towards prolateral; bulb large, with whitish protrusion dorsally and flat distal bulbal apophysis.

LEGS. Without spines, few vertical hairs; with curved hairs on legs 2 only (tibiae and metatarsi); retrolateral trichobothrium of tibia 1 at 6%; prolateral trichobothrium present on all tibiae; tarsus 1 with ~20 pseudosegments, distally distinct.

Male (variation). Tibia 1 in 4 other males: 3.7, 3.8, 4.2, 4.3. Abdomen length unusually variable (shortest abdomen 67% of longest abdomen).

Female. In general similar to male ( Fig. 240 ) but without curved hairs on legs. Tibia 1 in 12 females: 2.8–3.3 (mean 3.1). Epigynum simple plate ( Fig. 243 ), anteriorly evenly curved, posteriorly slightly pointed, with dark posterior margins interrupted medially by small whitish area; pair of internal structures and median ‘receptacle’ visible through cuticle. Internal genitalia with distinct median ‘receptacle’ and pair of lateral sclerites; pore plates apparently fused medially.

Notes. This species shares two potential synapomorphies with P. itaguyrussu and P. ybytyriguara and with males and females of undescribed species: (1) genital bulb with whitish protrusion dorsally (also present in the distantly related genus Carapoia González-Sponga, 1998 ); (2) pore plates more or less clearly fused medially (unknown in P. itaguyrussu and P. ybytyriguara ; also present in some distantly related taxa, e.g., Litoporus lopez Huber, 2000 ).

Distribution. Known from type locality only ( Fig. 348 ). Natural history. The spiders were collected on bromeliads approximately 1–2 m above the ground ( Fig. 340 ).

Their small webs were hidden deep among the leaf bases. Males and females were sometimes found close together

( Fig. 240 ). One egg-sac contained 13 eggs.

Figures

FIGURE 348. Known distribution of Psilochorus in the Atlantic Forest of Brazil. Red marks: undescribed species (L.S. Carvalho, B.A. Huber, unpubl. data). Five further South American nominal species are currently assigned to Psilochorus, but their identities and affinities are dubious (see text).

FIGURES 240–245. Psilochorus bromelicolus sp. n. (242–245: ZFMK, Ar 20647). 240–241. Live specimens; male (with short abdomen) and female with egg sac sharing web, and male (with long abdomen). 242. Male, dorsal view. 243. Epigynum, ventral view. 244–245. Cleared female genitalia, ventral and dorsal views. Scale lines: 1.0 (242), 0.2 (243–245).

FIGURES 246–248. Psilochorus bromelicolus sp. n. (ZFMK, Ar 20647). 246. Left procursus and genital bulb, dorsal view. 247–248. Left male palp, prolateral and retrolateral views. ba, bulbal apophysis; gb, genital bulb; pr, procursus. Scale lines: 0.3.

FIGURES 249–251. Psilochorus bromelicolus sp. n. (ZFMK, Ar 20647). 249–250. Male chelicerae, frontal and lateral views. 251. Cleared female genitalia, dorsal view. pp, pore plate. Scale lines: 0.2.

FIGURES 336–341. Selection of collecting sites and habitats. 336. Forest above Mokwam (West Papua), type locality of Arnapa arfak sp. n. and Aetana mokwam sp. n. 337. Tinoor Fall near Tomohon (North Sulawesi), type locality of Arnapa tinoor sp. n. 338. Entrance to Caverna Porco do Mato II (Rio Grande do Norte), type locality of Pinocchio barauna sp. n. 339. Desert between Sur and Kamil (Oman), type locality of Magana velox sp. n. 340. Bromeliad at Reserva Particular do Patrimônio Nacional Serra Bonita (Bahia), type locality of Psilochorus bromelicolus sp. n. (note pair of spiders among leaves). 341. Disturbed forest near Sofifi (Halmahera), type locality of Giloloa sofifi sp. n. and Panjange togutil sp. n.