Mesabolivar jamari, Huber, 2018

Huber, Bernhard A., 2018, The South American spider genera Mesabolivar and Carapoia (Araneae, Pholcidae): new species and a framework for redrawing generic limits, Zootaxa 4395 (1), pp. 1-178 : 20-23

Mesabolivar jamari sp. n.

Figs 9–10 , 55–57 , 59–60, 63–65 , 72–74

Diagnosis. Males are easily distinguished from most known congeners by extremely long distal element of procursus ( Figs 56–57 ; similar only in M. tapajos ); from M. tapajos by other details of tarsus and procursus (smaller tarsal process, position of dorsal process on procursus; compare Figs 57 and 58 ), by armature of male chelicerae ( Figs 59–60 ; apophyses stronger), and by shape of epigynum ( Figs 63–64 ; larger median depression bordered posteriorly by pocket with distinctive hood; conical lateral processes shorter; epigynum very similar to M. exlineae , but see Note below).

Note. The epigynum illustrated in Huber (2000) for Mesabolivar exlineae (Mello-Leitão, 1947) is very similar to the one shown here for M. jamari (compare Fig. 63 with Huber 2000: fig. 768). Unfortunately, M. exlineae is burdened with several problems: (1) the geographic origin is dubious. Mello-Leitão (1947a) gives “Pebas (Perú)” [3.31°S, 71.86°W, 110 m a.s.l.], while the label in the supposed type vial (BMNH 1940.12.30.108) reads “Capachica” [15.64°S, 69.83°W, 3850 m a.s.l.]. Previously, I considered Capachica the type locality and Mello- Leitão’s published locality an error (Huber 2000); however, Capachica is a high altitude place with a relatively dry climate, while all putatively close relatives ( M. pseudoblechroscelis , M. huambisa , M. paraensis , M. maraba , M. acrensis ) come from low altitude and high-precipitation areas. (2) The female illustrated in Huber (2000) may not be the holotype. As noted earlier (Huber 2000), Mello-Leitão’s (1947a) illustration of the epigynum looks quite different, even though the text mentions “two horns”. In sum, the supposed type vial in BMNH may be mislabeled, and the true type of M. exlineae may be lost or misplaced and originate from Pebas indeed.

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

Type material. BRAZIL: Rondônia: ♂ holotype, 1♀ paratype, UFMG (21503–04), 4♂ 5♀ paratypes, ZFMK (Ar 18954), Floresta Nacional do Jamari, ‘sites 2 & 3’ (9.22°S, 62.93°W – 9.26°S, 62.92°W), 110 m a.s.l., 24.x.2016 (B.A. Huber, L.S. Carvalho).

Other material examined. BRAZIL: Rondônia: 1♀ in pure ethanol, ZFMK (Br 16-301), same data as types ; 1♀ (apparently teratological, see below; assigned tentatively), ZFMK (Ar 18955), same data as types . 1♀, ZFMK (Ar 18956), Floresta Nacional do Jamari, Gran Piedra (9.198°S, 63.082°W), 160 m a.s.l., 25.x.2016 (B.A. Huber, L.S. Carvalho).

Description. Male (holotype)

MEASUREMENTS. Total body length 2.7, carapace width 1.25. Distance PME-PME 110 µm, diameter PME 130 µm, distance PME-ALE 100 µm, distance AME-AME 30 µm, diameter AME 40 µm. Sternum width/length: 0.95/ 0.60. Leg 1: 39.5 (9.7 + 0.5 + 9.6 + 17.5 + 2.2), tibia 2: 6.4, tibia 3: 4.4, tibia 4: 6.8; tibia 1 L/d: 83. Femora 1–4 width (at half length): 0.17, 0.19, 0.20, 0.18.

COLOR (in ethanol). Carapace ochre-orange, with black median line and pair of whitish areas beside ocular area; ocular area and clypeus not darkened; sternum medially slightly darker (orange to light brown); legs ochre to light brown, with darker rings on femora (subdistally) and tibiae (proximally and subdistally), tips of femora and tibiae whitish; abdomen greenish-gray, with dark internal marks dorsally and laterally, no ventral marks.

BODY. Habitus as in Fig. 9 ; ocular area raised (higher than usual in the genus); carapace with distinct median furrow; clypeus slightly swollen and whitish, with sclerotized margin; sternum unmodified.

CHELICERAE. With pair of long cylindrical apophyses with strongly sclerotized hooked tips ( Figs 59–60 ).

PALPS. As in Figs 55–56 ; coxa with conical retrolateral apophysis; trochanter with finger-shaped retrolateral apophysis; femur very large, proximally with retrolateral apophysis and prolateral hump set with short hairs; tarsus with large rounded dorsal process, with one strong and two regular hairs bent towards dorsal; procursus with widened median section, dorsal process, and long distal process apparently provided with gland and duct ( Fig. 57 ); bulb with distally bifid process.

LEGS. Without spines and curved hairs, few vertical hairs; retrolateral trichobothrium on tibia 1 at 2.5%; prolateral trichobothrium present on tibia 1; tarsus 1 with ~30 pseudosegments, distally fairly distinct.

Male (variation). Tibia 1 in four other males: 9.5, 9.6, 9.8, 10.7. Two males asymmetric with respect to trichobothria on palpal tibiae: one male with both trichobothria very proximally on one side; other male without proximal trichobothrium on one side.

Female. In general similar to male ( Fig. 10 ) but carapace ochre-brown rather than orange, with large brown median mark. Tibia 1 in seven females: 5.5–6.0 (mean 5.8). Epigynum as in Figs 63–64 , 72–73 ; anterior plate with large median depression bordered posteriorly by large pocket; pair of conical lateral processes directed obliquely towards posterior; posterior plate large, simple. Internal genitalia as in Figs 65 , 74 , with roughly triangular poreplates and distinctive median structure (arrow in Fig. 65 ; curved median tube, possibly to accommodate long processes of procursi). One female from type locality with much lower epigynal processes, apparently teratological; tibia 1 in this female: 5.4.

Natural history. The spiders were found very close to the ground, in webs that were mostly hidden in the leaf litter, under logs, or in small cavities in the ground. A small part of the domed sheet was visible from outside, and the spiders were resting in the back.

Distribution. Known from type locality in Rondônia state ( Brazil) only ( Fig. 722 ).

Figures

FIGURES 1–12. Live specimens, Mesabolivar pseudoblechroscelis group. 1–2. M. acrensis sp. n., male and female from Rio Branco. 3–4. M. maraba sp. n., male and female from Marabá. 5–6. M. huambisa Huber, 2000, male from Tabatinga, female from Belém.7–8.M.amazonicus sp. n., male and female from Humaitá.9–10.M.jamari sp. n., male and female from Jamari. 11–12. M.tapajos sp. n., male and female from Tapajós.

FIGURES 55–58. Mesabolivar jamari sp. n. (55–57, ZFMK Ar 18954) and M. tapajos sp. n. (58, ZFMK Ar 18957). 55–56. Left male palp,prolateral and retrolateral views.57–58.Left procursi, retrolateralviews (arrowspoint at putativeglands).Scale lines:0.5 (55–56), 0.3 (57–58).

FIGURES 59–68. Mesabolivar jamari sp. n. (59–60, 63–65, ZFMK Ar 18954) and M. tapajos sp. n. (61–62, 66–68, ZFMK Ar 18957–58). 59–62. Male chelicerae, frontaland lateral views.63–68.Epigyna, ventral and lateral views, and cleared female genitalia, dorsal views (arrows point at median arc-shaped ducts). Scale lines:0.3.

FIGURES 69–77. Female epigyna in ventral and lateral views and cleared female genitalia, dorsal views, Mesabolivar pseudoblechroscelis group (part 2). 69–71. M. amazonicus sp. n. (ZFMK Ar 18952). 72–74. M. jamari sp. n. (ZFMK Ar 18954).75–77.M.tapajos sp. n. (ZFMK Ar 18958).

FIGURES 722–723. Known distribution of the Mesabolivar pseudoblechroscelis group. For the dubious type locality of M. exlineae, see under description of M.jamari. TL, type locality.