Dysdera arnedoi Hernández-Corral 2017, new species
Creators: name: Hernández-Corral, Jesús
Publisher: name: Zenodo
Year: 2017
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Arachnida
Araneae
Dysderidae
Dysdera
Dysdera arnedoi

description: Dysdera arnedoi Lissner new species
Figs 1, 8–14, 30 –32
Type material. Holotype ♀ from Spain, Majorca, Pollença, Cova Morella, cave (39°50'39.7''N 2°59'2.5''E), 505 m, 23.IV.2014, J. Lissner leg.; deposited at NHMD.
Diagnosis. The vulva seems closest to those of its Majorcan congener Dysdera balearica Thorell, 1873 from which it differs by having 6 spines on Fe IV compared to 2–4 in D. balearica and by having the cheliceral teeth equidistant while the distal tooth in D. balearica is well separated from the two basal ones. The new species also differs by possessing troglobiomorphic features, such as appendage elongation, slight depigmentation and eye reduction, absent in D. balearica. The vulva of D. arnedoi n. sp. resembles those of D. apenninica Alicata, 1964, D. apenninica aprutiana Alicata, 1964 and D. lagrecai Alicata, 1964, but none of these species share the troglobiomorphic features found in D. arnedoi n. sp. Comparisons to other congeners of this large genus are made in the comments section.
Etymology. The species is dedicated to Miquel Arnedo in recognition of his important studies on woodlouse spiders, in particular those on species from the Canary Islands.
Description. Female. Measurements: Female (n=1): Total length 11.3; prosoma 4.1 long, 3.0 wide. Opisthosoma 7.3 long.
Colour: Cephalothorax orange red in live specimen fading to pale yellow in alcohol preserved specimen, head region slightly darker than thoracic region (fig. 1). Cephalothorax covered with fairly long dark hairs. Chelicerae slightly darker than head. Legs orange with leg I and II darker than III and IV. Abdomen pale covered with uniformly distributed short hairs.
Eyes (fig. 8): Sub-equal, rather small for the size of the spider; AM diameter 0.16; PL 0.17; PM 0.14; AM near anterior rim of frontal border and separated from each other by a little more than a diameter of an eye; PM nearly touching and separated from PL by less than half a diameter of PM; width of eye group equals 0.61.
Chelicerae: With three equidistant teeth (fig. 9).
Legs: This is a long-legged species (figs. 1, 11). Leg lengths are presented in Table 2.
Leg spination: Legs I–II spineless. All patellae and tarsi spineless. Fe III spineless, Fe IV with 6 dorsal spines distributed as in fig. 10. Five of these spines are in a row while the sixth is slightly displaced prolaterally. Spination of Ti III, IV and Mt III, IV is listed in table 3. Tarsal claws large, each with 12 well-developed pectinate teeth (fig. 12, 2 small teeth hidden by claw).
Vulva (figs 13–14, 30–32). Spermathecae oval, dorsal arch of anterior diverticulum in dorsal view with an anterior structure; bursal valve and transversal bar only seen in image of freshly removed vulva (fig. 30), during digestion in KOH they became detached from the anterior diverticulum. The lateral arms of the dorsal arch of anterior diverticulum do not reach the transversal bar.
The male is unknown.
Comments. The only troglobiomorphic Dysdera species known from Majorca so far. The species exhibits pronounced leg elongation, slight depigmentation and reduced width of eye group and eye size compared to epigean species. The new species was compared to the descriptions and illustrations of the 142 species presently known to occur in Europe (Nentwig et al., 2016; Le Peru 2011). The combination of characters possessed by D. arnedoi n. sp., in particular troglobiomorphism, leg spination, prosoma scabrousness, cheliceral dentation, shape of female genitalia and habitat occupied prevents targeting close relatives except for D. balearica, as mentioned in the diagnosis section. In the process of confirming a new species was at hand the specimen was compared to descriptions of other cave dwelling members of the genus (Dysdera bicornis Fage, 1931, D. espanoli Ribera & Ferrández, 1986, D. pavani Caporiacco, 1941, D. valentina Ribera, 2004, D. vivesi Ribera & Ferrández, 1986) and species with the most similar vulva (D. nubila Simon, 1882, D. osellai Alicata, 1973, D. subnubila Simon, 1907). Some of the distinctive characters separating these species from D. arnedoi n. sp. are presented below (Table 1). Dysdera apenninica Alicata, 1964 and the subspecies D. apenninica aprutiana Alicata, 1964 (both endemic to central Italy) and D. lagrecai Alicata, 1964 (endemic to Sicily) may have similar vulvae according to outline illustrations in Alicata (1964). Both species are epigean and confined to high ground (above 1.300 m), therefore they are not considered conspecific with D. arnedoi n. sp.
Adaptation to a cave life often leads to elongation of appendages (Kuntner et al., 1999). The Mt I/ prosoma length ratio is proposed here as a way to quantify the degree of troglobiomorphism in Dysdera, the higher the ratio the higher the degree of troglobiomorphism. Dysdera has radiated into many species in the Canary Islands to both epigean and hypogean environments. Using data available in Arnedo & Ribera (1999) Mt I/ prosoma length ratio of females average 0.59 (range 0.42–0.76) in epigean species (D. guayota Arnedo & Ribera, 1999, D. macra Simon, 1883, D. breviseta Wunderlich, 1992, D. minutissima Wunderlich, 1992, D. crocata, D. cribellata Simon, 1883, D. montanetensis Wunderlich, 1992) and 0.76 (range 0.51–1.21) in hypogean, more or less eyeless species (D. chioensis Wunderlich, 1991, D. esquiveli Ribera & Blasco, 1986, D. hernandezi Arnedo & Ribera, 1999, D. ambulotenta Ribera, Ferrández & Blasco, 1985, D. labradaensis Wunderlich, 1992, D. unguimmanis Ferrández & Blasco, 1985). The Mt I/ prosoma length ratio of the female D. arnedoi n. sp. is 0.83, thus grouping well within the hypogean species. The ratio is only surpassed by D. labradaensis Wunderlich, 1992 (0.87) and D. unguimmanis Ribera, Ferrández & Blasco, 1985 (1.21), the latter an extreme troglobiomorphic Dysdera (Arnedo & Ribera, 1999).
Distribution. A Majorcan endemic known from the Cova Morella cave near Pollença. The species possibly also occurs in the Coves de Campanet caves situated 5.6 km to the south of Cova Morella, because the DNA barcode sequence of an immature specimen from the latter cave is very similar to the one obtained from the new species (Miquel Arnedo, pers. comm.).
description: Published as part of Hernández-Corral, Jesús, 2017, The spider family Dysderidae in the Balearic Islands, pp. 375-391 in Zootaxa 4329 (4) on pages 376-380, DOI: 10.11646/zootaxa.4329.4.4, http://zenodo.org/record/1003034