Chibchea santosi Huber & Carvalho sp. n.

Figs 150–151, 157, 159, 162, 164, 167, 173–174, 191

Gen.n. Br16-178: Eberle et al. 2018 (molecular data); Huber et al. 2018: fig. 3.

Type material. BRAZIL: ♂ holotype, UFMG (22734); 3♀ paratypes, UFMG (22617, 22619, 22735); 4♀ paratypes, CHNUFPI (2538); and 3♂ 8♀ 1 juv. paratypes, ZFMK (Ar 20628), Acre, Cruzeiro do Sul, forest near Cruzeiro do Sul International Airport (7.596°S, 72.767°W), 200 m a.s.l., 30.x.2016 (B.A. Huber, L.S. Carvalho, E.O. Machado) .

Other material examined. BRAZIL: 1♀, UFMG (22613); and 1♀, ZFMK (Br 16-312), both in pure ethanol, same data as types . 6♀ 1 juv. in 80% EtOH, ZFMK (Ar 20629); and 1♂ 1♀, CHNUFPI (2500, 2523); 2♀, UFMG 921826, 22053); and 2♀ 1 juv., ZFMK (Br16-315) in pure ethanol, Amazonas, Guajará, forest at Fazenda Colorado, ‘site 1’ (7.525°S, 72.650°W), 225 m a.s.l., 31.x.2016 (B.A. Huber, L.S. Carvalho, E.O. Machado).

Etymology. The species is named for the Brazilian arachnologist Adalberto José dos Santos, coordinator of the Atlantic Forest Pholcidae project during which this species was collected.

Diagnosis. Distinguished from most similar known congeners ( C. hamadae, C. valle, C. amapa) by shapes of procursus and bulbal apophysis (Figs 159, 162; bulbal process with distinctive ventral sclerite proximally and large dorsal membranous process; procursus tip not bifid, narrower than in C. hamadae), by shape of process proximally on male palpal femur (Fig. 164), and by external and internal female genitalia (Figs 167, 173–174; epigynal plate semicircular, without posterior processes; narrow elongated pore plates converging anteriorly).

Description. Male (holotype). MEASUREMENTS. Total length 1.55, carapace width 0.70. Distance PME-PME 50 µm; diameter PME 80 µm; distance PME-ALE 40 µm; distance AME-AME 10 µm, diameter AME 20 µm. Leg 1: 10.3 (2.3 + 0.3 + 2.5 + 4.3 + 0.9), tibia 2: 1.7, tibia 3: 1.3, tibia 4: 1.7; tibia 1 L/d: 45.

COLOR (in ethanol). Carapace pale ochre-yellow with indistinct pattern of brown median mark including ocular area and brown lateral marginal bands; clypeus with pair of brown marks below eye triads; sternum brown; legs light brown, tips of tibiae whitish; abdomen pale greenish to blueish gray with blueish marks dorsally and laterally, ventrally with light brown mark in gonopore area and blueish band between gonopore and spinnerets.

BODY. Habitus as in close congeners (cf. Figs 148, 152). Ocular area slightly elevated. Thoracic furrow present. Clypeus unmodified. Sternum wider than long (0.50/0.34), unmodified.

CHELICERAE. Very similar to C. amapa (cf. Fig. 156), pair of processes on fangs mostly on posterior side (Fig. 157; barely visible in frontal view).

PALPS. Very similar to C. amapa (cf. Figs 154–155) but femur proximal process of different shape (Fig. 164); procursus with simple, narrow tip, not bifid (Fig. 159); bulbal process with distinctive ventral sclerite proximally, without serrated ventral sclerite distally (Fig. 162).

LEGS. Without spines and curved hairs, few vertical hairs; retrolateral trichobothrium of tibia 1 at 12%; tibia 1 without prolateral trichobothrium (present on other tibiae); tarsus 1 with ~20 indistinct pseudosegments.

Male (variation). Tibia 1 in 4 other males: 2.5, 2.5, 2.6, 2.7.

Female. In general similar to male but cheliceral fangs unmodified. Tibia 1 in 23 females: 1.8–2.3 (mean 2.1). Epigynum anterior plate large, semicircular (Fig. 173), internal V-shaped arc visible through cuticle; apparently without pockets; posterior plate short and simple, weakly sclerotized. Internal genitalia with pair of elongated pore plates converging anteriorly (Figs 167, 174). ALS with only two spigots each, one strongly widened, one pointed (Fig. 191).

Distribution. Known from two neighboring localities in the states of Acre and Amazonas, Brazil (Fig. 346).

Natural history. At the type locality, this species was found in a humid forest, in small holes in the ground under the leaf litter. It built tiny webs and ran away quickly when disturbed. At the forest at Fazenda Colorado, this was the only pholcid species found in a very dry patch of secondary forest close to a pasture; in a neighboring more natural and more humid patch of forest, eight species of Pholcidae were collected but not this species.