Mecolaesthus tuberculosus ( González-Sponga, 2003 )

Huber, Bernhard A. & Villarreal, Osvaldo, 2020, On Venezuelan pholcid spiders (Araneae, Pholcidae), European Journal of Taxonomy 718, pp. 1-317 : 108-113

Mecolaesthus tuberculosus ( González-Sponga, 2003)

Figs 344–345 , 365–366 , 369–372 , 379–381 , 1043

Maimire tuberculosa González-Sponga, 2009: 4 , figs 3a–j (♂ ♀).

Mecolaesthus tuberculosus – Huber et al. 2014a: 417.

Diagnosis

Distinguished from most congeners[except M.grandis ( González-Sponga,2009) and M.multidenticulatus ( González-Sponga, 2003) ] by armature of male chelicerae ( Figs 369–371 ; pair of large frontal processes curved downwards and set with 3–4 modified hairs each, and 1–2 small modified hairs more distally on weakly sclerotized area), by shape of main bulbal process (two large sclerites visible in prolateral view; cf. M. grandis and M. multidenticulatus , Figs 351 , 359 ), by transparent process on procursus distally bent toward retrolateral (cf. M. grandis and M. multidenticulatus , Figs 349 , 357 ), and by shape of epigynum ( Fig. 379 ; short but wide plate, pair of anterior internal sclerites extending towards lateral); from the very similar M. grandis and M. multidenticulatus by male cheliceral apophysis with conspicuous lateral process (arrow in Fig. 369 ) and bifid in lateral view ( Fig. 371 ), and by smaller distance between pair of rounded sclerites in female internal genitalia (arrows in Fig. 380 ); from M. grandis also by male cheliceral apophysis without conspicuous projection towards median ( Fig. 370 ).

Type material

VENEZUELA – Yaracuy • 4 ♂♂, 1 ♀, 3 juvs types (see Notes below), MIZA 105694 ( MAGS 111 ), Maimire (see Notes below), 15 Apr. 1981 (N. & T. Quiroz); examined .

New records

VENEZUELA – Yaracuy • 15 ♂♂, 7 ♀♀, ZFMK (Ar 21906–07), and 1 ♂, 4 ♀♀ in pure ethanol, ZFMK (Ven18-154), Yurubi National Park (10.4913° N, 68.6564° W), 140 m a.s.l., forest along stream, 16 Feb. 2020 (B.A. Huber, O. Villarreal M., Q. Arias C.) • 1 ♂, 1 ♀, ZFMK (Ar 21908), Guaquira , ‘site 1’ (10.2951° N, 68.6535° W), 120 m a.s.l., forest along stream, 16 Feb. 2020 (B.A. Huber, O. Villarreal M., Q. Arias C.) • 3 ♂♂, 3 ♀♀, ZFMK (Ar 21909), Guaquira , ‘site 2’ (10.2807° N, 68.6530° W), 150 m a.s.l., forest along stream, 17 Feb. 2020 (B.A. Huber, O. Villarreal M., Q. Arias C.) .

Assigned tentatively

VENEZUELA – Falcón • 1 ♂, 1 ♀, 1 juv., ZFMK (Ar 21910), and 1 juv. in pure ethanol, ZFMK (Ven18-148), forest near Santa Cruz de La Alegría (10.8795° N, 68.4949° W), 100 m a.s.l., 15 Feb. 2020 (B.A. Huber, O. Villarreal M., Q. Arias C.)

Notes

The type series includes 4 ♂♂, 1 ♀, 3 juvs rather than 2 ♂♂, 4 ♀♀, 1 juv. as in the original description. Since all specimens are joined in one vial (contrary to the original description), it is not clear which of the four males is the holotype. Thus, all specimens are simply treated as types. The four males appear identical, so there is currently no need to designate a lectotype.

We were not able to exactly identify the type locality.The longitude in the original publication (11.017° W) is obviously wrong, and the file card gives an altitude of 1200 m while the original description says 1100 m. The collecting site was probably approximately at 10.205° N, 69.016° W. In 2020, the site was not accessible due to security reasons. Our two new sites in Yaracuy are ~ 40 km ENE and ~ 50 km NE of the type locality, respectively.

Redescription

Male (ZFMK Ar 21906)

MEASUREMENTS. Total body length 3.4, carapace width 1.2. Distance PME–PME 90 µm; diameter PME 110 µm; distance PME–ALE 80 µm; diameter AME 30 µm; distance AME–AME 20 µm. Leg 1: 42.2 (9.9 +0.5 +10.1 +19.4 +2.3), tibia 2: 6.0, tibia 3: 4.5, tibia 4: 5.4; tibia 1–4 diameters: 100 µm, 120 µm, 130 µm, 125 µm; tibia 1 L/d: 101.

COLOR (in ethanol). Carapace ochre-yellow with wide median and lateral marginal dark bands not connected posteriorly, ocular area mostly not darkened, clypeus with wide dark brown mark; sternum pale ochre-yellow, labium brown; legs ochre to light brown, with indistinct darker rings on femora subdistally and on tibiae proximally, femora and tibiae with light tips; abdomen pale greenish-gray, dorsally and laterally with dark bluish marks, ventrally with light brown mark in gonopore area, dark brown book lung covers, pair of lateral anterior brown plates opposing fourth coxae, and large bluish median marks in front and behind gonopore; with small light brown mark above pedicel opposing carapace inflation.

BODY. Habitus as in Fig. 344 . Ocular area distinctly raised. Carapace anteriorly with distinct thoracic groove, posteriorly slightly inflated. Clypeus unmodified. Sternum wider than long (0.86/0.60).Abdomen slightly elongated, pointed at spinnerets.

CHELICERAE. As in Figs 369–371 , with pair of large frontal apophyses, each with prominent lateral process; each apophysis with ~3 slightly hooked short hairs and 2–3 straight strong hairs in addition to

regular setae, with 1–2 additional short hairs on whitish area below each apophysis, and tiny weakly sclerotized ridge.

PALPS. Apparently indistinguishable from M. grandis and M. multidenticulatus (cf. Figs 346–353 , 356– 361 ). The simultaneous comparison of two specimens from each species suggested that the variation within localities is comparable to the variation among species.

LEGS. Without spines and curved hairs; few vertical hairs; retrolateral trichobothrium of tibia 1 at 2%; prolateral trichobothrium present on all leg tibiae; tarsus 1 with ~35 pseudosegments, mostly distinct.

Male (variation)

Tibia 1 in 15 males from Yaracuy: 8.3–10.2 (mean 9.4); book-lung covers in some males barely darkened; some males without or with indistinct pair of anterior ventral abdominal plates and without plate above pedicel; carapace in some males not or barely inflated. In the male from Santa Cruz de La Alegría the lateral process on the cheliceral apophysis is less distinct. Specimens from this locality are therefore assigned tentatively; tibia 1: 9.1.

Female

In general similar to male ( Fig. 345 ), but never with brown plates opposing fourth coxae, never with brown plate above pedicel, and carapace never inflated. Tibia 1 in eight females: 5.0–6.6 (mean 5.9). Epigynum and internal genitalia ( Figs 372 , 379–381 ) very similar to those of M. grandis and M. multidenticulatus but pair of internal rounded sclerites closer together (arrows in Fig. 380 ). Internal sclerites variably visible in uncleared specimens. The small differences between Figs 355 , 364 , and 372 may in part result from preparation artifacts.

Distribution

Known from three localities in the Venezuelan state Yaracuy, and from specimens assigned tentatively from Falcón (Fig. 1043).

Natural history

Both in Yurubi National Park and in Santa Cruz de La Alegría this species shared the microhabitat with Mesabolivar eberhardi Huber, 2000 , i.e., large spaces among rocks and trunks near the ground. The spiders hang in their relatively large webs that were not particularly hidden and vibrated strongly when disturbed.

Figures

Figs 338–345. Mecolaesthus Simon, 1893; live specimens. 338–340. M. grandis (González-Sponga, 2009); male and female with egg sac from La Guaira, El Limón (arrow: brown plate above pedicel opposing carapace inflation). 341–343. M. multidenticulatus (González-Sponga, 2003); male and female with egg sac from Falcón, Curimagua. 344–345. M. tuberculosus (González-Sponga, 2003); male and female with egg sac from Yaracuy, Yurubi National Park.

Figs 365–366. Mecolaesthus tuberculosus (González-Sponga, 2003); type from Yaracuy, Maimire (MIZA 105694; MAGS 111); left male pedipalp, prolateral and retrolateral views. Scale line: 0.3 mm.

Figs 367–372. Mecolaesthus Simon, 1893; male chelicerae, distal, frontal and lateral views; cleared female genitalia, dorsal view. 367. M. grandis (González-Sponga, 2009); from La Guaira, El Limón (type locality; ZFMK Ar 21899) (arrow: distinctive projection towards median). 368. M. multidenticulatus (González-Sponga, 2003); from Falcón, Curimagua (type locality; ZFMK Ar 21904). 369– 372. M. tuberculosus (González-Sponga, 2003); from Yaracuy, Yurubi National Park (ZFMK Ar 21906– 07) (arrow: distinctive lateral process). Scale lines: 0.3 mm (all chelicerae at same scale).

Figs 373–381. Mecolaesthus Simon, 1893; epigyna, ventral views and cleared female genitalia, ventral and dorsal views (arrows: internal rounded sclerites). 373–375. M. grandis (González-Sponga, 2009); from La Guaira, El Limón (type locality; ZFMK Ar 21900). 376–378. M. multidenticulatus (González- Sponga, 2003); from Falcón, Curimagua (type locality; ZFMK Ar 21905). 379–381. M. tuberculosus (González-Sponga, 2003); from Yaracuy, Yurubi National Park (ZFMK Ar 21907).

Figs 348–355. Mecolaesthus grandis (González-Sponga, 2009); from La Guaira, El Limón (type locality; ZFMK Ar 21899–21900). 348–350. Left palpal tarsus and procursus, prolateral, dorsal, and retrolateral views. 351–353. Left genital bulb, prolateral, dorsal, and retrolateral views. 354. Male chelicerae, frontal view. 355. Cleared female genitalia, dorsal view. Scale lines: 0.3 mm.

Figs 356–364. Mecolaesthus multidenticulatus (González-Sponga, 2003); from Falcón, Curimagua (type locality; ZFMK Ar 21904–05). 356–358. Left palpal tarsus and procursus, prolateral, dorsal, and retrolateral views. 359–361. Left genital bulb, prolateral, dorsal, and retrolateral views. 362–363. Male chelicerae, frontal and lateral views. 364. Cleared female genitalia, dorsal view. Scale lines: 0.3 mm.

Figs 346–347. Mecolaesthus grandis (González-Sponga, 2009); holotype from La Guaira, Hacienda El Limón (MIZA 105663; MAGS 1215); left male pedipalp, prolateral and retrolateral views. Scale line: 0.3 mm.