Pholcus sveni, WUNDERLICH, 1987

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 : 70-71

PHOLCUS SVENI WUNDERLICH, 1987 ( FIGS 44–61 )

Pholcus sveni Wunderlich, 1987: 80 , figs 93–101.

Material examined: 1 m, holotype, from La Gomera, Canary Islands, Spain ( SMF 35555) ; 1 m, 2 ff, 1 juv., La Gomera, Valle Gran Rey , 28.ii.2002, Dimitrov & De Mas ( CCRUB 4618-173 , 4548-171 , 4606-173 ) ; 1 f, La Gomera, Valle Gran Rey , 28.ii.2002, Dimitrov & De Mas ( ULL AÑ-2154 ) ; 1 f, La Gomera, Las Hayas , 28.ii.2002, Dimitrov & De Mas ( CCRUB 4616-173 ) ; 1 m, 1 f, 1 juv., La Gomera, Barranco de Agaga , 16.viii.2004, Dimitrov & Antón ( CCRUB 4549–171 ) .

Diagnosis: Very similar to P. gomerae and P. bimbache . Easily distinguished from P. bimbache by the shorter claw-shaped apophyses of the appendix and the shape of the uncus ( Figs 45 , 53 ). Procursus with shorter, dorso-retrolateral spines ( Figs 45 , 54 ). Apical apophysis of the procursus ( Fig. 57 ) with longer ventral outgrowth at the tip. The upper margin of the proximolateral apophyses of the chelicerae does not extend to the base of the proximal prominence ( Figs 49 , 51 ). The female valve has a more arched ridge than in P. gomerae , but less so than in P. bimbache . Pore plates are smaller than in P. bimbache ( Fig. 47 ).

Description: Male: prosoma oval with brownishyellow colouring. Dorsally, the dark markings typical of the Canarian Pholcus species are visible. Fovea well marked. Elevated ocular area with darker pigmentation and long dorsal hairs. Eyes surrounded by brownish colouring. Distance between AME equal to their diameter, while the distance between them and ALE slightly larger than the ALE diameter. AME diameter one-third the diameter of ALE. Sternum yellowish with darker central zone and brownish margins. Chelicerae brownish with darker distal cheliceral apophyses ( Figs 49 , 51, 52 ). Near the base of the distal cheliceral apophyses a group of modified hairs (bristles) is visible. Tip of distal apophyses carries three modified hairs ( Fig. 58 ). Upper margin of proximolateral apophyses does not extend to the base of frontal prominences. Palps as in Figures 44, 45, 48 . Procursus with robust terminal apophysis with two small, conical outgrowths ( Fig. 56 ). Procursus’ apical apophysis terminates with longer ventral, and shorter dorsal outgrowths ( Fig. 57 ). Opisthosoma cylindrical with yellowish pigmentation. Dorsally, six darker spots distributed in two longitudinal lines are visible. Ventrally, a darker transversal line is visible over the genital area. Gonopore as in Figure 59 . Spinnerets as in Figures 60, 61 .

Female: prosoma as in male but with less elevated ocular area. Eyes closer together, with the distance between AME and ALE smaller than the ALE diameter. Chelicerae without apophyses. Sternum as in the male but with lighter colouring. Opisthosoma as in the male. Ventrally, a darker arching line is visible over the triangular plate. Epigynum and vulva as in Figures 46, 47, 50 .

Measurements: Male: Prosoma 1.1 long, 1.3 wide; opisthosoma 2.9 long, 0.9 wide. Total body length 4.0. Leg I, femur 8.8, patella 0.5, tibia 8.8, metatarsus 14.7, tarsus 2.4, total 35.6. Palp: femur 0.7, patella 0.3, tibia 0.8, procursus 0.7. Female: Prosoma 1.5 long, 1.7 wide; opisthosoma 4.0 long, 1.5 wide. Total body length 5.5. Leg I, femur 9.0, patella 0.5, tibia 9.3, metatarsus 15.1, tarsus 1.9, total 35.8.

Distribution: This species is endemic to La Gomera where it is known to inhabit the Valle Gran Rey and Barranco de Argaga ( Fig. 276 ).

Natural history: P. sveni was collected in several localities at low altitude in the Gran Rey valley. Few specimens were found in the adjacent Barranco de Argaga close to sea-level. The surroundings of these valleys are very dry with steep slopes and xerophytic vegetation. However, their lower parts are much more humid. In Valle Gran Rey almost the entire area is covered with numerous agricultural plots and houses. In both localities P. sveni lives in lower areas under large stones, always close to small pools of water.

Comments: P. sveni is very similar to P. gomerae and P. bimbache both in the morphology of the procursus’ apical part and the bulb’s appendix. These similarities are also common to the Tenerife species. This again underlines the close relationships among the fauna of the archipelago’s occidental islands: Tenerife, La Gomera and El Hierro.

Figures

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

Figures 44–50. Pholcus sveni: 44, male palp, prolateral; 45, male palp, retrolateral; 46, epigynum, lateral; 47, vulva, dorsal; 48, male palp, frontal; 49, male chelicerae, frontal; 50, epigynum, ventral. Scale bars 0.2 mm.

Figures 51–61. Pholcus sveni: 51, male chelicerae, frontal; 52, male chelicerae, lateral; 53, projections of the bulb, prolateral; 54, procursus, retrolateral; 55, apex of the procursus, ventral; 56, procursus, prolateral; 57, apical apophysis of the procursus, ventral; 58, distal apophysis of male chelicerae, retrolateral; 59, male gonopore, ventral; 60, posterior median spinnerets; 61, anterior lateral spinnerets. Scale bars: 51–54, 56, 200 µm; 55, 57 and 59, 100 µm; 58, 20 µm; 60, 61, 10 µm.