Three new species of pholcus (araneae, pholcidae) from the Canary Islands with notes on the genus Pholcus in the Archipelago.
Keywords: Araneae, Pholcidae, Pholcus new species, taxonomy, Canary Islands
The Canary Islands are situated about 100 km off the northwestern coast of Africa. This volcanic archipelago was formed during various volcanic episodes and is nowadays composed of seven main islands and several islets. All of them are situated almost on a straight line with an east-west orientation, with the age of the islands decreasing towards the east. The estimated ages of the islands are: Fuerteventura 20-22 My, Lanzarote 15-19 My, Gran Canaria 14-16 My, Tenerife 11.6-14 My, La Gomera 10-12 My, La Palma 1.6-2 My and El Hierro 0.8-1 My (Anguita & Hernan 1975; Ancochea et al. 1990; Coello et al. 1992).
The older islands, Fuerteventura and Lanzarote, are lower in elevation due to the effects of erosion. As a result of their low height they receive less moisture from the northeast trade winds than the other, higher islands. This, and the proximity of the Sahara Desert, renders them the driest islands in the archipelago, with most of their habitats being dry lowlands. The remainder of the Canary Islands have higher mountains, reaching an elevation of 3717 m (Teide, Tenerife). This high elevation combined with the trade winds (humid from the northeast and dry from the northwest), causes a thermic inversion that forms a cloud belt between 600 and 1000 m. These clouds are almost permanent on the northern slopes, favoring the growth of a characteristic subtropical forest named laurel forest.
Differences in humidity and elevation between and within islands are the main reasons for the development of a large variety of habitats. The so-called hypogean environment also contributes to changes in the diversity of habitats. In the case of the Canaries it is formed by lava tubes and the MSS (mesocavernous shallow stratum) (Oromf et al. 1986; Medina 1991). This high diversity of ecological niches and the initial emptiness of habitats provide the best conditions for species radiations.
The spider genus Pholcus Walckenaer 1805 is a good example of this process. The 114 species that it comprises are distributed almost all around the world. However, it is interesting to note that there are no indigenous Pholcus species in Central and South America and only a few are known from North America.
Before the present study, eighteen species of Pholcus had been reported from the Canary Islands. This represents more than 15% of the total number of species of this genus. If we add to them the five species from Madeira (another Macaronesian island), this ratio reaches more than 19%. At the same time, the area of these islands represents an extremely small part of the total area of the generic distribution, providing clear evidence of a species radiation on the Canary Islands.
Apart from the cosmopolitan P. phalangioides (Fuesslin 1775), the remaining species of Pholcus recorded from the Canary Islands are endemic to this archipelago. Two of them have been collected from more than one island: P. ornatus Boesenberg 1895 has the broadest distribution, occurring on all the islands except Lanzarote and Fuerteventura; and P. fuerteventurensis Wunderlich 1991 is found on Fuerteventura and Gran Canaria. Pholcus knoeseli Wunderlich 1991, P. malpaisensis Wunderlich 1991, P. mascaensis Wunderlich 1987, P. baldiosensis Wunderlich 1991, P. roquensis Wunderlich 1991, P. intricatus Dimitrov & Ribera 2003 and P. tenerifensis Wunderlich 1987 are endemic to the island of Tenerife. Pholcus multidentatus Wunderlich 1987, P. calcar Wunderlich 1987, P. corcho Wunderlich 1987, P. edentatus Campos & Wunderlich 1995 and P. helenae Wunderlich 1987 are known only from the island of Gran Canaria, while P. gomerae Wunderlich 1980, P. gomeroides Wunderlich 1987 and P. sveni Wunderlich 1987 are endemic to La Gomera.
In the present work, three new endemic species of Pholcus are described. Pholcus bimbache is the first endemic Phoclus species from El Hierro; P. anachoreta is endemic to the Montana Clara islet and P. corniger is the second and most troglomorphic species of this genus known from this archipelago. With these three new species the number of Canarian endemic species of Pholcus reaches twenty, eighteen of which are mono-insular endemics, indicating that the genus has a higher diversity in the Canary Islands than previously suspected.
Pholcus corniger is the most troglomorphic species of Pholcus known from the Canaries. While in P. baldiosensis, the other troglomorphic species, the reduction of the eyes is incomplete, in P. corniger they are totally absent. This species, unfortunately, may be extinct due to the destruction of its habitat in Cueva de San Miguel, where residual waters are thrown out of houses nearby. This seems to be still a common practice in the Canaries, affecting numerous volcanic tubes and small caves. Estimating how many species suffer from this particular activity and how many are brought to extinction will be a difficult task. Taking into account the high vulnerability of both cave faunas and island ecosystems, Canarian authorities and the Spanish government should implement more active and efficient measures to eliminate these type of activities.
Specimens were examined under a Wild Heerbrugg (12-100X) stereomicroscope. The female vulva was removed and treated with 50% solution of lactic acid in order to render the remaining soft tissues transparent. After observation and drawing the vulva were washed in distilled water and stored in 70% ethyl alcohol. All measurements are in millimeters. The total body length is the sum of the prosoma and the opisthosoma omitting the pedicel. The specimens are deposited in the Departament de Biologia Animal, Universitat de Barcelona (CCRUB). The numbers of the collection are given in brackets.
Family Pholcidae C.L. Koch 1851 Genus Pholcus Walckenaer 1805 Pholcus bimbache new species Figs. 1-9
Material examined.--Holotype male, Cueva del Juaclo de las Moleras, Frontera, El Hierro, Canary Islands, 27[degrees]43'N, 18[degrees]08'W, 7 November 1991, C. Ribera (CCRUB 3523-140). Paratypes: Canary Islands: 1 female, same locality and date as holotype, C. Ribera (CCRUB 3524-140) (drawings and description of the female are based on this specimen); 1 male, 2 females and 8 juveniles (CCRUB 3522, 3525 to 3527-140) same locality and date as holotype; 1 male and 1 juvenile, same locality, 4 February 2000, N. Mercader & E. Munoz (CCRUB 4505-170).
Etymology.--The species is named after the original inhabitants of El Hierro island, the so-called "Bimbaches".
Diagnosis.--Pholcus bimbache can be distinguished from similar Canarian species (P. sveni and P. gomerae) by the less pronounced callosity of the procursus, the narrower base of the uncus (Fig. 5), the longer claw-shaped apophysis of the appendix and the long, almost straight trochanteral apophysis (Fig. 6) of the male palp (Figs. 1-3); also, by the shape of the apophyses of the male chelicerae (Fig. 4). The diagnostic characters of the female are the shape of the epigynum and the large oval pore plates of the vulva (Figs. 7-9).
[FIGURES 1-9 OMITTED]
Description. Male (holotype): Prosoma yellowish with well marked cephalothoracic junction and fovea. Ocular area elevated. Thorax with brown marking, wider than long, which starts at the fovea and extends to the posterior margin of the prosoma. It has three lighter zones dividing it into four darker radial lobes. Sternum brown-yellowish with borders slightly darker brown. Distance between AME equal to their diameter. Distance AME-ALE slightly more than two times the diameter of AME; AME-PME three times the diameter of AME. Anterior eye line frontal view slightly recurved. Posterior eye line dorsal view recurved. Clypeus high with yellowish color. Chelicerae (Fig. 4) yellow-brownish; cheliceral apophyses brownish with cylindrical shape finishing with small darker outgrowths; upper margin of the proximolateral apophyses does not reach the lower margin of the frontal prominence. A few dark bristles are placed near the base of the cheliceral apophyses. Palps (Figs. 1-3) with yellow-brownish color, trochanter with long retrolateral apophysis (Fig. 6), femur large with ventral bulge, procursus with dark process of the apical apophysis. Opisthosoma elongated, almost cylindrical, whitish with small darker transversal zone in the genital area.
Female (paratype): All characters as in male except: less elevated ocular area, distance between AME slightly less than their diameter, distance AME-ALE slightly less than two times the diameter of the AME, AME-PME two and half times the diameter of the AME. Chelicerae without apophyses. Genital zone without pigmentation except the sclerotized zone of the epigynum. By transparence some parts of the vulva can be observed. Epigynum and vulva as in (Figs. 7-9).
Measurements.--Male (holotype): Prosoma 1.2 (1.2) wide, 1.3 (1.3) long; opisthosoma 1.1 (1.5) wide and 2.5 (3.0) long. Total body length 3.8 (4.3). Legs: I, femur 8.7(9.2), patella 0.5(0.5), tibia 8.1(9.5), metatarsus 13.2(14.3), tarsus 2.0(2.2), total 32.5(37.5); II 6.5(7.0), 0.5(0.5), 6.0(6.5), 9.0(8.5), 1.3(1.5), 23.3(24.0); III 5.0(5.0), 0.5(0.5), 4.0(4.2), 6.2(7.0), 1.0(1.0), 16.7(17.7); IV 6.3(7.0), 0.5(0.5), 5.8(6.2), 8.0(9.0), 1.2(1.1) 21.8(23.9). In brackets male paratype no. 3522-140. Palp: femur 0.60, patella 0.18, tibia 0.50, tarsus 0.20, total 1.48. Procursus 0.8.
Female: Prosoma 1.3 wide, 1.2 long; opisthosoma 1.5 wide, 3.5 long; total body length 4.7. Legs: I, femur 9.0, patella 0.7, tibia 8.2, metatarus 14.0, tarsus 1.2, total 33.1; II 6.5, 0.7, 8.6, 9.2, 1.2, 23.6; III 5.0, 0.7, 4.5, 6.5, 1.0, 17.7; IV 7.0, 0.7, 5.0, 9.0, 1.2, 22.9. Palp femur 0.40, patella 0.14, tibia 0.19, tarsus 0.3, total 1.03.
Distribution.--This species is endemic to El Hierro, and is only known from the type locality.
Remarks.--Pholcus bimbache appears to be related to members of the so-called Tenerifensis group (Wunderlich 1987, 1991; Dimitrov & Ribera 2003) composed of ten species (seven in Tenerife and three in Gomera). Here we should note that the term "Tenerifensis group" is used as merely descriptive and does not imply any phylogenetic relationship. All these species are characterized by the claw-shaped apophysis of the appendix, and by the shape of both the uncus and the lamella of the procursus. Pholcus sveni Wunderlich 1987 is the most similar species. Pholcus bimbache can be distinguished from it by the longer and more curved claw-shaped apophysis, the shape of the procursus and the morphology of both the epigynum and the vulva. The presence of this species on El Hierro Island emphasizes the close faunistic relationships between Tenerife, La Gomera and El Hierro.
Pholcus anachoreta new species Figs. 10-18
Material examined.--Holotype male, Montana Clara islet, Canary Islands, 29[degrees]18'N, 13[degrees]31'W, 24 April 1994, C. Ribera (CCRUB 2459-99). Paratypes: Canary Islands: 1 male, 1 female, same locality, 23-27 November 2002, A.J. Perez (CCRUB 4502, 4503-170); 1 juvenile, from the same locality, 27 January 2002, P. Oromi (CCRUB 4504-170).
Etymology.--The name comes from the Greek word "anachoretes" meaning person who lives in a lonely place dedicated to contemplation. This word was adopted in the Latin as anachoreta-ae keeping the male gender. Named after the remoteness and isolation of the type locality.
Diagnosis.--Pholcus anachoreta is easily distinguished from canarian congeners by the serrated keel of the uncus (Fig. 15), the morphology of the apex of the procursus (number and shape of the apophyses and lamellas) and the cheliceral apophyses (Fig. 13). The female can be distinguished from the most similar canarian species (P. fuerteventurensis and P. edentatus) by the lower sclerotized plate of the epigynum (Figs. 16, 17) and the more arced ridges of the valve (Fig. 18).
Description.--Male (holotype): Prosoma whitish without a clearly marked fovea and practically indistinguishable cephalothoracic junction. The prosoma does not carry hairs except for its borders and the intraocular area. Ocular area elevated. Sternum with a whitish coloring. Clypeus high and whitish. Chelicerae (Fig. 13) whitish; cheliceral apophyses darker with conical shape and group of 2-3 thick bristles placed near the base. The proximolateral apophyses (proximal teeth) and the frontal prominence show the same coloring as the rest of the chelicerae. The upper margin of the proximolateral apophyses is higher than the lower margin of the frontal prominence. Distance between AME less than their diameter. The rest of the eyes situated in two elevated triads. AME around 50% of the size of the other eyes. Anterior eye line frontal view slightly recurved. Posterior eye line dorsal view recurved. Palps as in Figs. 10-12. Trochanter (Fig. 14) with long curved retrolateral apophysis, femur with ventral bulge, procursus very complex with many apical lamellae and with three distal dorsal spines. Uncus (Fig. 15) very characteristic with serrated keel. Opisthosoma elongated and cylindrical with whitish color, dorsally darker. A longitudinal zone with darker pigmentation starting from the genital area and followed by two tear-shaped spots is observed ventrally.
[FIGURES 10-18 OMITTED]
Female (paratype): Prosoma: all characters as in male except for the cheliceral apophyses, which are absent. Sizes and distribution of the eyes as in the male but the elevation of the ocular area is less conspicuous. Opisthosoma cylindrical with yellowish coloring. The genital zone is darker, with brownish pigmentation. Dorsally with two parallel lines of dark spots. The whole opisthosoma is covered with short and regularly distributed hairs. Epigynum and vulva as in Figs. 16-18.
Measurements.--Male (type): Prosoma 1.2 wide, 1.0 long; opisthosoma 1.0 wide, 3.1 long; total body length 4.1. Legs: I, femur 9.5, patella 0.4, tibia 12.0, metatarsus 16.0, tarsus 2.0, total 39.9; II 6.2, 0.4, 6.0, 10.0, 1.0, 23.6; III 5.0, 0.4, 4.2, 7.0, 1.0, 17.6; IV 7.0, 0.4, 6.0, 6.5, 0.8, 20.7. Palp femur 0.8, patella 0.2, tibia 0.7, tarsus 0.3, total 2.0. Procursus 0.75
Female: Prosoma 1.9 wide, 1.5 long; opisthosoma 1.8 wide, 4.0 long; total body length 5.5. Legs: I, femur 8.3, patella 0.5, tibia 8.0, metatarsus 12.9, tarsus 1.9, total 31.6; II 6.4, 0.5, 5.6, 9.6, 1.5, 23.6; III 4.9, 0.5, 4.9, 7.3, 0.9, 18.5; IV 6.8, 0.5, 5.6, 8.8, 1.7, 23.4. Palp femur 0.34, patella 0.10, tibia 0.24, tarsus 0.24, total 0.92.
Distribution.--This species appears to be endemic to Montana Clara and is known only from type locality, although it might occur in the neighboring islets of Graciosa and Alegranza and in Lanzarote island considering their geographical vicinity.
Remarks.--The structure of the procursus of this species is similar to that of P. edentatus Campos & Wunderlich 1995 and P. fuerteventurensis Wunderlich 1992. Similar fingerlike lamellae in the procursus allow the three species to be distinguished from the rest of the Canarian Pholcus. Despite of this remarkable similarity the procursus and the uncus are very different and therefore very useful for specific identification.
Pholcus corniger new species Figs. 19-32
Material examined.--Holotype male, Cueva de San Miguel, San Miguel de Abona, Tenerife, Canary Islands, 28[degrees]06'N, 16[degrees]36'W, 1 January 1991, P. Oromi (CCRUB 4500-170). Paratype: Canary Islands: 1 female from the same locality, 1 January 1991, P. Oromi (CCRUB 4501-170).
Etymology.--The specific name refers to the shape of the elevated ocular area reminding horns. The word "corniger" in Latin means "with horns".
Diagnosis.--Pholcus corniger can be easily distinguished from the rest of canarian Pholcus species by the simplified structure of the procursus with single membranous lamella on its apex, the presence of six teeth and the absence of basal bristles on the cheliceral apophyses (Fig. 26). The female is differentiated by the elevated conically shaped epigynum (Figs. 27-29). This species can be easily distinguished by the total reduction of the eyes (both in male and female) and the shape of the elevated ocular area that reminds horns (Figs. 19-22).
Description.--Male (holotype): Prosoma with an ochre-yellow coloring and well-marked fovea and cephalic furrow. Eye area elevated with characteristic shape and brown coloring (Figs. 19-20), with group of hairs between the ocular elevations. Clypeus high, yellowish with brownish spot in the center and almost transparent at the edges. Sternum yellowish. Chelicerae yellow-brownish, with brown apophyses carrying six dark brown teeth without bristles at the base (Fig. 26). Frontal prominence small. The upper margin of the proximolateral apophyses roughly reaching the lower margin of the frontal prominence. Eyes completely missing. Palps as in Figs. 23-25. Uncus as in Fig. 31. Trochanter (Fig. 32) with retrolateral apophysis, femur with ventral bulge. The procursus is very characteristic, conspicuously different from those of the remaining species of Canarian Pholcus. While in all the other species the apical part of the procursus is very complex and carries one or various apophyses and lamellar processes, in P corniger it is much simpler and ends with a single membranous lamella. This lamella extends along all the apex of the procursus. Opisthosoma cylindrical with pale yellowish color.
Female (paratype): Like the male, although the elevations of the ocular area are much smaller and colored like the rest of the prosoma (Figs. 21, 22). Prosoma lighter. Clypeus almost transparent. The genital area is not pigmented except for the sclerotized parts of the epigynum. Epigynum and vulva as in Figs. 27-30. As in the male, eyes are absent.
Measurements.--Male (holotype): Prosoma 1.1 wide and 1.0 long; opisthosoma 1.0 wide and 2.5 long. Total body length 3.5. Legs: I, femur 7.0, patella 0.3, tibia 7.0, metatarsus 11.5, tarsus 1.3, total 27.1; II 5.5, 0.3, 5.2, 8.0, 1.2, 20.2; III 4.0, 0.3, 3.9, 5.3, 1.0, 14.5; IV 6.5, 0.3, 5.0, 7.0, 1.0, 19.8. Palp femur 0.50, patella 0.10, tibia 0.50, tarsus 0.28, total 1.38. Procursus 0.4
[FIGURES 19-26 OMITTED]
[FIGURES 27-32 OMITTED]
Female: Prosoma 1.1 wide, 1.0 long; opisthosoma 1.1 wide, 2,2 long; total body length 3.2. Legs: I, femur 7.0, patella 0.3, tibia 6.5, metatarsus 11.0, tarsus 1.8, total 26.6; II 6.2, 0.3, 5.0, 7.2, 1.1, 19.8; III 4.0, 0.3, 3.8, 5.0, 0.8, 13.9; IV 6.0, 0.3, 5.0, 7.0, 1.0, 19.3. Palp femur 0.24, patella 0.07, tibia 0.19, tarsus 0.30, total 0.80.
Distribution.--Endemic to the island of Tenerife, only known from the type locality.
Remarks.--Determining the closest relatives is difficult for this species. Taking into account the shape of the uncus, this species can be associated to the Tenerifensis group (see above). On the other hand, though, the epigynum of the female is very different from those of the Tenerifensis group, and it looks more similar to that of P. baldiosensis Wunderlich 1992 (the other troglomorphic species). Unfortunately, we cannot determine whether the male of P. baldiosensis is in fact similar to the Tenerifensis group since it still remains unknown.
Taking in account the characteristic features of the epigynum and the procursus, which are remarkably different from those of the other Canarian Pholcus species, P. corniger could possibly be a member of a different group, or it could form a subgroup (with P. baldiosensis) of the Tenerifensis group. In order to yield an answer to this question, a detailed phylogenetic study must be performed.
We would like to thank to Dr. Pedro Oromi and the other members of the Department of Biology at the Universidad de La Laguna for their inestimable help and collaboration. We thank also to Salvador Carranza for critically reading manuscript. This research was supported by BOS2002-00629 project from the Ministerio de Ciencia y Tecnologia of the Spanish Government.
Manuscript received 17 February 2004, revised 10 September 2004.
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Dimitar Dimitrov (1) and Carles Ribera: Departament de Biologia Animal, Universitat de Barcelona, Av. Diagonal, 645, Barcelona-08028, Spain. E-mail: email@example.com
(1) Current address: George Washington University, Department of Biological Sciences, 2023 G. Street, NW, Washington, DC, 20052. E-mail: dimitardC& gww.edu
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|Author:||Dimitrov, Dimitar; Ribera, Carles|
|Publication:||The Journal of Arachnology|
|Date:||Jan 1, 2006|
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