Pholcus gomerae, WUNDERLICH, 1980

Dimitrov, Dimitar & Ribera, Carles, 2007, The genus Pholcus (Araneae, Pholcidae) in the Canary Islands, Zoological Journal of the Linnean Society 151 (1), pp. 59-114 : 67-70

PHOLCUS GOMERAE WUNDERLICH, 1980 ( FIGS 25–43 )

Pholcus gomerae Wunderlich, 1980: 223 , figs 14–22; Wunderlich, 1987: 80, figs 102–112.

Pholcus gomeroides Wunderlich, 1987: 81 , figs 113– 117. New synonymy.

Synonymy justification: Having examined type material of Pholcus gomerae ( SMF 29976), as well as various paratypes from both this species and P. gomeroides (see below), we could find no significant differences between them. Furthermore, numerous Pholcus specimens collected from La Gomera were examined with similar conclusions. The original description of P. gomeroides contained very few drawings, and in fact none of the female, a strange omission given that there were then females available. Detailed comparison of the female epigynum and vulva revealed them to be practically identical. The differences noted by Wunderlich (1987) should be regarded as intraspecific variations. Such differences in the apical apophyses of the procursus (‘lamella’ sensu

Wunderlich, 1987) and the positioning of the procursus’ dorsal spines are visible in the rest of the Pholcus species.

Material examined: Pholcus gomeroides : 1 m, holotype from La Gomera, Canary Islands, Spain ( SMF 35557) ; 2 mm, 2 mm subad., 1 f subad., paratypes from La Gomera ( SMF 35558) . Pholcus gomerae : 1 m, holotype from La Gomera ( SMF 29976) ; 2 ff, paratypes from La Gomera ( SMF 29977) ; 3 mm, 4 ff, 2 juv., from La Gomera, El Cedro , 27.ii.2002, Dimitrov & De Mas ( CCRUB 4544-171 , 4538-171 , 4537-171 , 4645-173 , 4617-173 , 4603-173 , 4602-173 ) ; 5 mm, 8 ff, from La Gomera, Epina , 28.ii.2002, Dimitrov & De Mas ( CCRUB 4539-171 - 4543-171 , 4600-173 , 4615-173 ) ; 1 m, La Gomera, Epina , 28.ii.2002, Dimitrov & De Mas ( ULL AÑ-2149 ) ; 2 mm, 1 juv., La Gomera , Chorros de Epina, 19.viii.2004, Dimitrov & Antón (4544- 171); 3 mm, 2 ff, La Gomera, Las Mimbreras, 17– 28.ii.2002, Dimitrov & De Mas ( CCRUB 4536-171 , 4604-173 ) ; 1f La Gomera, Las Mimbreras , 17– 28.ii.2002, Dimitrov & De Mas ( ULL 4646-173 ) ; 1 m, 1 f, La Gomera, Las Mimbreras , 20.viii.2004, Dimitrov & Antón ( CCRUB 4546-171 ) ; 3 mm, 1 f, 2 juv., La Gomera, near Las Mimbreras , 20.viii.2004, Dimitrov & Antón ( CCRUB 4547-171 , 4545-171 ) .

Diagnosis: P. gomerae is distinguished from its most similar congener, P. sveni , by the following characteristics: longer spines over the retrolateral side of the procursus ( Fig. 39 ); two apical outgrowths, nearly equal in length, on the apical apophysis of the procursus ( Fig. 37 ); and the less curved apophysis of the trochanter. Other distinctive characteristics of the male include the shape of the bulb’s appendix, the shape of the uncus ( Figs 26 , 41 ), and the apophyses of the chelicerae ( Figs 30 , 32, 33, 40 ). The diagnostic characteristics of the female include a less elevated triangular plate and the shape of the valval ridge, which in P. gomerae is less arched ( Fig. 28 ).

Description: Male: yellowish prosoma with brownish dorsal marking over thoracic area. Dorsal marking divided into two parts by the fovea, which is yellowish in colour like the rest of the prosoma. Both parts contain a yellowish spot more or less oval in shape. Borders of the dorsal marking irregular and not extending to the prosoma’s exterior margin. The eyes, on an ocular elevation, with the same colouring as the prosoma except for the interocular area, which has dark brown pigmentation. Frontal part of ocular elevation with a brownish marking. Distance between lateral triads three times the diameter of ALE. Diameter of AME half the diameter of ALE, while distance between them nearly equal to the ALE diameter. Dorsally, the ocular area with hairs considerably longer than those of the prosoma. Sternum yellowish with brownish margins. Chelicerae brownish-yellow, distal cheliceral apophyses ( Figs 40, 33 ) brownish with cylindrical shape and three small distal outgrowths (modified hairs). At the base of distal cheliceral apophyses ( Figs 30 , 32 ) is placed a group of thick modified hairs – bristles. Upper margin of proximolateral apophyses (proximal teeth) higher than the lower margin of frontal prominences. Proximal prominences with large base, nearly onethird the width of the chelicerae. Chelicerae as in Figures 30 , 32, 33 . Palp as in Figs 25, 26, 29 , with yellowish pigmentation; trochanter with long retrolateral apophysis; procursus heavily sclerotized with dark brown colouring. Procursus as in Figures 38, 42, 43 . Apical apophysis of the procursus carries two nearly equal outgrowths at the tip, the ventral with a shorter conical spine at its base ( Fig. 37 ). Procursus with well-developed terminal apophysis lacking conical elevation and with a small apical depression ( Fig. 43 ). Long legs with yellowish colouring, darker than prosoma. Opisthosoma cylindrical with yellowish pigmentation. Dorsally, four brownish spots in the shape of an inverted V are visible. Size and intensity of spot pigmentation decreases towards the distal part of the opisthosoma. Spinnerets feature darker markings on their basal areas. Spinnerets as in Figures 35, 36 . Ventrally, the genital area with darker pigmentation. Gonopore as in Figure 34 .

Female: prosoma as in male except for the less elevated ocular area and the shorter distance between AME and ALE, which is half the ALE diameter. Chelicerae lack apophyses. Opisthosoma cylindrical with slightly lighter pigmentation than in the male. Elevated epigynum with a brownish band over a strongly sclerotized triangular plate. Epigynum as in Figures 27, 31 ; vulva as in Figure 28 .

Measurements: Male: Prosoma 2.4 wide, 2.7 long; opisthosoma 2.1 wide, 4.9 long. Total body length 7.6. Leg I, femur 15.6, patella 0.9, tibia 15.1, metatarsus 25.4, tarsus 2.8, total 59.8. Palp, femur 0.9, patella 0.3, tibia 1.3, procursus 1.2. Female: Prosoma 2.3 wide, 2.0 long; opisthosoma 3.2 wide, 5.4 long. Total body length 7.4. Leg I, femur 13.6, patella 0.9, tibia 14.6, metatarsus 23.5, tarsus 1.9, total 54.5.

Distribution: This species is endemic to La Gomera Island. Its distribution is restricted to the higher zones of the island ( Fig. 276 ).

Natural history: P. gomerae is very common, with quite numerous populations throughout the laurisilva forests of La Gomera. It builds its webs in small excavations near mountain roads or cavities on the hillsides. The drainage pipes of the road network proved to be one of the best places to collect this species. Several specimens were found in cavities between the roots of large trees. In some of the populations the individuals were very clustered, leaving just a couple of centimetres between each other, and it was practically impossible to distinguish individual webs.

Comments: The morphology of the male palp, particularly the shape of the procursus and the uncus, suggests that this species is very closely related to P. sveni . These two species differ not only in their morphology but also in their preferred habitats. In contrast to P. gomerae , P. sveni is found outside the forest, specifically in ravines in the southern part of the island.

Figures

Figure 276. Known distribution of Pholcus species endemic to the Canary archipelago.

Figures 25–31. Pholcus gomerae: 25, male palp, prolateral; 26, male palp, retrolateral; 27, epigynum, lateral; 28, vulva, dorsal; 29, male palp, frontal; 30, male chelicerae, frontal; 31, epigynum, ventral. Scale bars 0.2 mm.

Figures 32–43. Pholcus gomerae: 32, male chelicerae, frontal; 33, male chelicerae, lateral; 34, male gonopore, ventral (Dimitrov & Ribera, 2005a); 35, anterior lateral spinnerets; 36, posterior median spinnerets; 37, apical apophysis of the procursus, ventral; 38, procursus, dorsal; 39, small teeth on the procursus, dorsal; 40, apex of the distal apophysis of male chelicerae; 41, projections of the male bulb, dorso-retrolateral; 42, procursus, retrolateral; 43, procursus, prolateral. Scale bars: 33, 38, 41–43, 200 µm; 34, 37, 39, 100 µm; 36, 40, 20 µm; 35, 50 µm; 32, 500 µm.