Mecolaesthus longissimus Simon, 1893

Huber, Bernhard A. & Villarreal, Osvaldo, 2020, On Venezuelan pholcid spiders (Araneae, Pholcidae), European Journal of Taxonomy 718, pp. 1-317 : 139-142

Mecolaesthus longissimus Simon, 1893

Figs 494–505 , 1021, 1045

Mecolaesthus longissimus Simon, 1893a: 320 .

Mecolaesthus longissimus – Simon 1893b: 479–482. — Caporiacco 1955: 299. — Huber 1997d: 588, figs 12a–e, 13a–d; 2000: 256, figs 79, 136, 180, 1014–1023; 2005a: 573–581, figs 1–8. — González- Sponga 2010: 18, pl. 4, figs 1–11.

Notes

In a first redescription of the species ( Huber 1997d), a lectotype was chosen from the type series (MNHN, E. Simon collection number 11024). In this vial, specimens from two localities (Colonia Tovar and Corosal) had been joined by E. Simon, without specifying the numbers of specimens from each locality. This vial contains 13 ♂♂, one of which deviates in its cheliceral armature (by the presence of an additional pair of apophyses, cf. Huber 1997d: fig. 12e; Huber 2000: fig. 1018; González-Sponga 2010: pl. 4, fig. 3). Extensive new material from near Colonia Tovar ( Huber 2005a and below) suggests that the majority of the males in the type vial (including the lectotype) are from Colonia Tovar and that the deviating male is from Corosal. The type locality can therefore be specified more precisely as Colonia Tovar.

Whether or not males with the additional pair of apophyses represent a distinct species remains an open question. The redescriptions in Huber (2000) and González-Sponga (2010) are based on such specimens. A comparison of the illustrations in Huber (2000: figs 1019–1023) with Figs 499–505 (made from topotypical specimens) suggests that additional morphological differences exist. No fresh material is available of the ‘deviating morph’, but we predict that a detailed morphological comparison combined with molecular data may eventually justify a formal split of this species.

The material published by González-Sponga (2010) is present in the MIZA collection but the respective collection cards are missing so it is not clear which vial represents which locality listed in González-

Sponga (2010). The following seven vials are thought to represent this material (specimen counts partly approximate): 9 ♂♂, MIZA 105702 (MAGS 244); 2 ♂♂, 4 ♀♀, MIZA 105740 (MAGS 964); 1 ♀, MIZA 105688 (MAGS 965); 1 ♂, 1 ♀, 1 juv., MIZA 105610 (MAGS 1023); 9 ♂♂, 3 ♀♀, 12 juvs, MIZA 105597 (MAGS 1039); 4 ♂♂, 4 ♀♀, MIZA 105631 (MAGS 1088); 4 ♂♂, 6 ♀♀, 5 juvs, MIZA 105635 (MAGS 1091). This material supposedly originates from the following localities:

La Guaira: Hacienda El Limón [10.475° N, 67.283° W]

Miranda: Hacienda Santa Rosa, 8 km N Guatire [approximately 10.53° N, 66.56° W]

Miranda: Hacienda Salmerón [approximately 10.483° N, 66.367° W]

Miranda: Guatopo National Park, Boca de Cura [10.20° N, 66.30° W]

Miranda: Guatopo National Park, Panaquire [10.216° N, 66.239° W]

Miranda: Guatopo National Park, Macanilla [locality not identified] We have not checked Caporiacco’s (1955) female specimen. However, a male from the same locality (Rancho Grande, Aragua) was studied in Huber (2000), so we consider Caporiacco’s record as possibly correct.

New records

VENEZUELA – Aragua • 9 ♂♂, 9 ♀♀, 1 juv., ZFMK (Ar 21939), and 2 ♂♂, 1 ♀ in pure ethanol, ZFMK (Ven20-162), Henri Pittier National Park , forest near La Cumbre (10.3575° N, 67.5771° W), 1450 m a.s.l., 20 Feb. 2020 (B.A. Huber, O. Villarreal M.). – La Guaira • 18 ♂♂, 13 ♀♀, 4 juvs, ZFMK (Ar 21940–41), and 4 ♂♂, 3 ♀♀, 2 juvs in pure ethanol, ZFMK (Ven18-161), between Colonia Tovar and El Junquito (10.4230° N, 67.2381° W), 1960 m a.s.l., 10 Nov. 2018 (B.A. Huber, O. Villarreal M.) • 3 ♂♂, 3 ♀♀, 4 juvs, MIZA 105691 ( MAGS 992 ), Arco de la Colonia Tovar [10.421° N, 67.242° W], 22 Nov. 1986 (A.R. Delgado, M.A. González S.) • 1 ♀, ZFMK (Ar 21942), El Limón , ‘site 1’ (10.4788° N, 67.3010° W), 600 m a.s.l., forest remnant along small stream, 21 Feb. 2020 (B.A. Huber, O. Villarreal M.). – Anzoátegui • 2 ♂♂, 1 juv., MIZA 105596 ( MAGS 1035 ), near Sabana de Uchire [approximately 10.02° N, 65.52° W], 2 Mar. 1987 (A.R. Delgado de G., M.A. González S., M. Ruedas). – Miranda • 1 ♀, MIZA 105811 ( MAGS 313 ), Turgua [10.370° N, 66.756° W], 25 Jul. 1981 (A.R. Delgado de G., J.A. González D., M.A. González S.) • 1 ♀, MIZA 105671 (separated from MAGS 1169), “ rio Aricagua, Dtto. Brión ” [approximately 10.621° N, 66.203° W], 10 m a.s.l., 27 Aug. 1989 (M.A. González S.) • 1 ♀, MIZA 105669 (separated from MAGS 1165), Los Amarillos, old road Caracas-Charallave [10.367° N, 66.945° W], Jul. 1989 (A.R. Delgado, M.A. González-S.) • 1 ♂, MIZA 105638 (separated from MAGS 1098), Boca de Cura [10.205° N, 66.291° W], 11 Oct. 1987 (A.R. Delgado, M.A. González S.) • 1 ♀, MIZA 105727 ( MAGS 1017 ), Salmerón [approximately 10.468° N, 66.376° W], 250 m a.s.l., 10 Jan. 1987 (A.R. Delgado, M.A. González S.) • 1 ♂, 1 ♀, MIZA, El Volcán, Topotepuy [10.417° N, 66.851° W, ~ 1450 m a.s.l.], 11–13 Nov. 2019 (O. Villarreal, J. Rodríguez) .

Description (amendments; see Huber 1997d, 2000, 2005a)

Eye measurements (male from Colonia Tovar): distance PME–PME 130 µm; diameter PME 120 µm; distance PME–ALE 80 µm; diameter AME 35 µm; distance AME–AME 20 µm. Tibia 1 measurements (specimens from Colonia Tovar in Huber 2005a and specimens listed below) in 56 males: 10.3–12.8 (mean 11.5); in 33 females: 6.6–8.5 (mean 7.5).

All males from Colonia Tovar with dark median band on carapace and dark ochre to black ocular area and clypeus, without lateral dark bands; legs in males without or with very indistinct dark rings, in females with dark rings on femora subdistally and on tibiae proximally and subdistally; abdomen without brown anterior plate(s), book-lung covers in males variable ( not darkened to brown), in females never brown. Coxa 4 unmodified. Prolateral trichobothrium present on all leg tibiae. Procursus ( Figs 500–502 ) with large dorsal process proximally, small retrolateral apophysis, and distinctive tip with dorsal and ventral sclerites connected by transparent membrane and prolateral process with tiny scales. Genital bulb ( Figs 503–505 ) with large distal process partly membranous/whitish, partly with distinctive sclerites.

Epigynum ( Fig. 497 ) consisting of small brown plate surrounded by whitish membranous cuticle, with distinctive pair of anterior internal structures visible in uncleared specimens; posterior plate slender transversal sclerite widening laterally. Internal genitalia complex and difficult to understand, with pair of semispherical pore plates, possible median duct and receptacle ( Figs 498–499 ).

Distribution

Common in – and apparently restricted to – the Coastal Ranges in Venezuela (Fig. 1045) .

Natural history

In Colonia Tovar, the spiders were found in a well-preserved forest above the town; between Colonia Tovar and El Junquito they were found in a forest remnant close to a small stream. At both localities, the distribution appeared to be very patchy. During our second visit to Colonia Tovar in 2018 we tried to revisit the spot from the 2002 trip but could not locate it and did not find a single specimen of M. longissimus (even though the forest looked exactly as in 2002). Between Colonia Tovar and El Junquito, the species was abundant in a small area at the stream but apparently absent from nearby parts of the forest. The spiders were collected from strongly domed webs with a diameter of ~ 20 cm, between about 20 cm to 150 cm above the ground. When disturbed the spiders vibrated vigorously in their webs but did not drop to the ground.

In Henri Pittier National Park the species was abundant, often in exposed webs up to 1.5 m above the ground. One large male was introduced to the web of another large male. Within a minute, the two males started to fight, first with their front legs only. Then each male made a few vigorous jerks with the abdomen, flexing it strongly and rapidly toward ventral, but without contacting the opponent. After this, one male left toward the periphery of the web and both males remained silent. This observation supports the idea than males of this species use their extremely elongated (and positively allometric) abdomens in male-male fights ( Huber 2005a).

Figures

Figs 494–499. Mecolaesthus longissimus Simon, 1893; from Aragua, Colonia Tovar-Junquito; live males (large and small specimens) and female with egg sac; epigynum, ventral view; cleared female genitalia, ventral and dorsal views (female genitalia: ZFMK Ar 21941).

Figs 500–505. Mecolaesthus longissimus Simon, 1893; from Aragua, Colonia Tovar (type locality; ZFMK Ar 21940). 500–502. Left palpal tarsus and procursus, prolateral, dorsal, and retrolateral views. 503–505. Left genital bulb, prolateral, dorsal, and retrolateral views. Scale lines: 0.2 mm.