Agroeca dentigera Kulczynski, 1913

Felton, C. J. & Merrett, P., 2004, Agroeca dentigera Kulczynski, 1913, a liocranid spider new to Britain (Araneae, Liocranidae), Bulletin of the British Arachnological Society 13 (1), pp. 90-92 : 91-92

Agroeca dentigera Kulczynski, 1913 ( Figs. 1-4 )

Agroeca dentigera Kulczynski, 1913: 26 , pl. 1, fig. 10 (descr. ♀).

Agroeca dentigera: Braun, 1967: 179 , figs. 1-2 (♀); Wunderlich, 1975: 44, figs. 6-10 (♀, descr. ♂); Jocque, 1977: 80, figs. 1-4 (♀ ♂); Grimm, 1986: 28, figs. 28-29 (♀♂); Heimer & Nentwig, 1991: 388, fig. 1013 (♀); Roberts, 1998: 147, figs. (♀ ♂).

Material examined: GREAT BRITAIN: Ceredigion, Ynyslas Dunes (part of Dyfi National Nature Reserve ), grid ref. SN 607936 , pitfall trap on flat fixed dune, 1♀, 1 October 1989, leg. A. Fowles, coll. S. Dobson ; same locality, SN 606934, sloping, south-facing fixed dune, 4♀ 1♂, 10 October 2002, leg. and coll. C. Felton, det. P. Merrett, deposited in Liverpool Museum (National Museums Liverpool) .

Female/male: Total length 5.45-5.90/4.5. Carapace length 2.45-2.75/2.3. Abdomen length 3.0-3.45/2.4. Coloration similar to A. brunnea (Blackwall) , but pattern and ground colour somewhat lighter. Carapace with thin dark borderline. Abdomen with central dorsal stripe not well defined; with irregular pattern of dark bars and blotches. Legs sometimes with very faint annulations on tibiae. Eyes: AME slightly smaller than ALE, but equal in size to PME. AME slightly closer together than to ALE, posteriors almost equidistant, but position variable. Anterior eye row approximately straight, posterior row procurved. Legs: All femora usually with 3 dorsal spines, femur I with 1 prolateral spine, femur III usually with 2 prolateral and 1 retrolateral spine. All tibiae usually with 2 pairs of ventral spines and all metatarsi with 3 pairs of ventral spines, but some variation (tibiae III and IV sometimes with 3 pairs). Male palp ( Figs. 1-2 ): Tibial apophysis broad and truncated. Bulbus with large, proximally curved, tegular apophysis, and embolic division with smaller, thin, distally curved process, which appears very fine in ventral view but thicker and curved dorsally in lateral view. Epigyne ( Figs. 3-4 ): Fairly close to that of A. lusatica , but central atrium broader anteriorly and rather heart-shaped. With pair of dark, eyelid-like sockets, or ‘‘retinacula’’, either side of midline.

Diagnosis: The male is easily distinguished by the shape of the tibial apophysis of the palp in lateral view; it is closest to that of A. proxima but clearly distinct, and the palpal bulb is very different. The bulb is closest to that of A. brunnea , but the thin, distally curved process on the embolic division is distinctive. The epigyne is closest to that of A. lusatica , but the central atrium is broader and more heart-shaped in A. dentigera , and the prominent eye-lid like sockets either side of the midline are distinctive. The general form of the epigyne is also like that of A. brunnea , but in A. brunnea the posterior ‘‘cleft’’ in the epigyne is much longer, and the anterior broad atrium is much shorter.

Distribution and habitat

Agroeca dentigera was originally described by Kulczynski (1913) from a single female from the region of Valuyki (Belgorod region) in southern Russia. A second female was described by Braun (1967) from Sphagnum near Bremen in north-west Germany, collected on 12 October 1962. Oltean (1973) found a third female in a reedbed in the Danube delta in Romania. The male was described for the first time by Wunderlich (1975), who reported on a collection of 48 males and 10 females obtained by pitfall trapping in the region of Berlin, on a Carex moor partially invaded by Alnus , and in association with Typha and Phragmites . Jocque (1977) described 4 males and 3 females which were taken in pitfall traps in Kalmthout, Belgium, among Calluna and Molinia . Other more recent records have come from The Netherlands, Sweden, Finland, Lithuania, Poland, Ukraine, and the southern Urals.

The species therefore appears to be widespread in central and eastern Europe, but is rare with very few records. It has been collected mainly in the autumn and winter months, from October onwards, like most other Agroeca species. The available information on habitats is rather limited, but some degree of dampness is a common feature of most of the records.

At Ynyslas Dunes, A. dentigera was collected only on fixed dune habitat, in a south-facing hollow on an east-west oriented dune. Ammophila arenaria is dominant at the site, with other grasses, mostly Festuca sp., which is abundant in a rank sward together with moss and little bare ground. In addition to evening primrose, Oenothera biennis L., and other herbs there is some encroachment by burnet rose, Rosa pimpinelli ­ folia L., which forms dense patches nearby. The spiders were found on sloping ground, running on litter under the vegetation. Agroeca dentigera would appear to be very restricted and uncommon at Ynyslas Dunes. Considerable effort was devoted to searching for it over two years at 20 different places on the site, yet it was found at only one location. Interestingly, this was less than 200 m from where the original specimen was found in 1989. The occurrence of the species on the west coast of Wales and nowhere else in Britain is remarkable. From its continental distribution, it might be expected to occur in south-east England, if anywhere in Britain.

Ynyslas Dunes support an important assemblage of 121 spider species (Judd et al, 2003) and, in addition to A. dentigera , which presumably will receive RDB status, six nationally scarce species have been recorded: Philo ­ dromus fallax Sundevall ( Philodromidae ), Marpissa Agroeca dentigera new to Britain nivoyi (Lucas) ( Salticidae ), Dipoena inornata (O. P.- Cambridge) ( Theridiidae ), Maso gallicus Simon , Mecopisthes peusi Wunderlich and Ceratinopsis romana (O. P.-Cambridge) ( Linyphiidae ). Agroeca proxima is widely distributed across the dune system, and the related and nationally scarce Agraecina striata (Kulczynski) has been recorded from adjacent habitat at Cors Fochno and upper saltmarsh of the Dyfi estuary (M. Bailey, pers. comm.).

Figures

Figs. 1 - 4: Agroeca dentigera Kulczynski. 1 Right male palp, retrolateral view; 2 Ditto, hairs omitted, ventral view; 3 Epigyne, ventral view, 2002 specimen; 4 Epigyne, ventral view, hairs omitted, 1989 specimen. Scale lines = 0.2 mm.