Chibchea santosi 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 : 45-49

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.

Figures

FIGURE 346. Known distribution of Chibchea in Brazil.

FIGURES 148–153. Chibchea spp., live specimens. 148–149. C. amapa sp. n., male and female with egg sac. 150–151. C. santosi sp. n., females with egg sacs. 152–153. C. hamadae sp. n., male and female with egg sac.

FIGURES 156–163. Chibchea spp., chelicerae frontal view and cheliceral fang, posterior view (156–157) (arrows point at processes on fangs), left procursi, retrolateral views (158–160), and left bulbal processes, prolateral views (161–163) (arrow points at distinctive proximal ventral sclerite). 156, 158, 161. C. amapa sp. n. (ZFMK, Ar 20626). 157, 159, 162. C. santosi sp. n. (ZFMK, Ar 20628). 160, 163. C. hamadae sp. n. (ZFMK, Ar 20630). Scale lines: 0.1 (procursi and bulbal processes at same scale each).

FIGURES 164–168. Chibchea spp., male left palpal femora, retrolateral views (164–165), and cleared female genitalia, dorsal views (166–168). 164, 167. C. santosi sp. n. (ZFMK, Ar 20628). 165, 168. C. hamadae sp. n. (ZFMK, Ar 20630). 166. C. amapa sp. n. (ZFMK, Ar 20626). pp, pore plates. Scale lines: 0.2 (femora and cleared epigyna at same scale each).

FIGURES 169–176. Chibchea spp., male in dorsal and lateral views, epigyna in ventral views, and cleared female genitalia in dorsal views. 169–172. C. amapa sp. n. (ZFMK, Ar 20626). 173–174. C. santosi sp. n. (ZFMK, Ar 20628). 175–176. C. hamadae sp. n. (ZFMK, Ar 20630). Scale lines: 0.3 (171–176), 1.0 (169–170).

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).

FIGURES 154–155. Chibchea amapa sp. n. (ZFMK, Ar 20626). Left male palp, prolateral and retrolateral views. Scale line: 0.3.