Diplocephalus guidoi, Frick, Holger & Isaia, Marco, 2012

Frick, Holger & Isaia, Marco, 2012, Comparative description of the Mediterranean erigonine spider Diplocephalus guidoi n. sp. (Araneae, Linyphiidae), Zootaxa 3475 (1), pp. 65-68 : 65-68

Diplocephalus guidoi new species

( Figs 1–10 )

Type material. HOLOTYPE male (and allotype female): Italy: Piedmont: Cuneo : Aisone , Valle Stura , Vallone della Valletta , loc. Pinet , Parco Naturale Alpi Marittime , 1540 m, in a small stream at the border of a mountain path with mosses and other aquatic vegetation [7.225 E, 44.286 N], 11.IX.2011, leg. M. Isaia and R. Galindo ( MCSNB).

PARATYPES from same sample as holotype, 33 8Ƥ (2Ƥ at MI; 23, 2Ƥ at NMBE, Ar7251 ; 13, 4Ƥ at MCSNB) .

Examined material. Italy: Piedmont: Same locality, same habitat as holotype, 1560 m [7.225 E, 44.285 E], 13 2Ƥ, 11.IX.2011, leg. M. Isaia and R. Galindo (at HF). Italy: Piedmont: A few hundred meters south from holotype locality, 1530 m, in a small spring among mosses and wet stones [7.225 E, 44.281 N], 33, 17.VIII.2010, leg. M. Isaia, R. Galindo, A. and G. Vigna (23 at MI; 13 at HF) .

Etymology. The species is dedicated to Guido Badino, Professor of Ecology at the University of Turin and member of the Science Academy of Turin, for his personal and noble commitment to his work and for mentoring and supporting Marco Isaia's academic career. It also refers to Guido Frick, whose love to nature inspired his grand son Holger Frick to become a biologist. The species epithet is a name in apposition.

Diagnosis. Males can be distinguished from species with similar palpal conformations by the presence of a small post PME-lobe instead of a PME-lobe ( Fig. 1 ) and the retrolateral facing prolateral tibial apophysis being covered behind the tibia in dorsal view ( Figs 6, 7 ). The form of the distal suprategular apophysis with its sclerotized main branch and the membranous inner section is species specific ( Figs 3, 4 ). Females can be separated from similar species (see remarks) by the protrusions on the two lobes formed by the ventral plate ( Figs 8, 9 ). Similar structures are also found in other species but then situated below the ventral plate rather than on top of it ( Fig. 11 ).

Description. Male: (NMBE Ar7251, paratype): colours slightly variable. Total length: 2.04. Cephalothorax: smooth, yellowish brown (464U); 1.01 long, 0.82 wide, with cephalic post-PME lobe ( Fig. 1 ), clypeus smooth. Eyes: AME smallest, ALE largest, PME and PLE of equal size, separated by less than their diameter. Chelicerae: stridulatory striae imbricated, proximally compressed; six (five big, one small) promarginal teeth, four retromarginal denticles. Sternum: smooth, brown (465U); 0.59 long, 0.62 wide. Legs: orange-brown (153U); tibial spine formula 2211; TmI: 0.54; leg formula 4-1-2-3. Pedipalp: pale brown (467U), patella ratio length/width = 2.1 ( Fig. 7 ); tibia with one retrolateral and one prolateral trichobothrium ( Fig. 7 ); prolateral tibial apophysis small, hidden behind the tibia with marginal teeth at its tip ( Figs 6, 7 ); cymbium with glabrous retrolateral lobe, lacking a striated protrusion at its dorsal side ( Fig. 3 ); paracymbium with two basal hairs ( Fig. 3 ); tegulum with small protegulum ( Fig. 4 ); suprategular apophysis with marginal apophysis, sclerotized distal apophysis and inner apophysis with folded basal section and membranous pointy tip ( Figs 3, 4 ); embolic division complex; embolus lamellar with curved tip, continuous with the anterior radical process ( Fig. 3 ); anterior radical process distinct, directed distally, longitudinally folded without retrolateral striations, tip curved ventrally ( Figs 3, 4 ); radical tailpiece with broad tip and inner margin ( Fig. 4 ).

Females: (NMBE Ar7251, paratype): Colours slightly variable. Total length: 2.63. Cephalothorax: smooth, dark brown (1545U); 1.08 long, 0.85 wide; general appearance as male, but without cephalic lobe, clypeus squamate. Eyes: posterior row procurved, anterior row straight, AME smallest, ALE, PLE and PME of equal size, separated by less than their diameter. Chelicera: six (five big, one small) promarginal teeth, four retromarginal denticles. Sternum: smooth, brown (1535U); 0.65 long, 0.63 wide. Legs: brown (1535U); tibial spine formula 2200; TmI: 0.51; leg formula 4-1-2-3. Epigynum: pale with sclerotized sections; ventral plate bisected, bearing a round appendix on each of its two lobes; anterior side of ventral plate with orthogonal margin, posterior edges squared ( Fig. 8 ). Vulva: spermathecae globular, visible in ventral view, fertilisation ducts directed mesally ( Fig. 10 ).

Distribution. Findings of D. guidoi n. sp. are so far restricted to the only locality of Pinet, in the small valley of Vallone della Valletta in the North-western corner of Parco Naturale Alpi Marittime, Valle Stura, Province of Cuneo, SW Italian Alps. However, it is likely that the species is more widespread in the district of Alpi Marittime (also on the French side), an area that is well known for its remarkable biodiversity and its high rate of endemism ( Minelli et al., 2006).

Habitat. Findings of D. guidoi n. sp. are restricted to the type locality. Specimens were found in hygropetric habitat, among mosses and small stones, in a wet area, close to a mountain spring.

Phenology. Altogether three specimen of D. guidoi n. sp. were found on 17 August 2010 and another 16 at the 11 September 2011. Collection failed on a survey performed on 28.X.2010. However, since the new species has only been sampled at two occasions, it is difficult to draw any phenological conclusions.

Remarks. The genus Diplocephalus includes 52 species with very diverse palpal morphology and is thus difficult to define. However, based on palpal morphology it is possible to form phenetic groups of species sharing particular characters. Diplocephalus guidoi n. sp. can be assigned to a group of species including the Mediterranean species D. arnoi Isaia, 2005 , D. longicarpus (Simon, 1884) , D. pavesii Pesarini, 1996 and D. procer (Simon, 1884) plus the Caucasian D. caucasicus Tanasevitch, 1987 and D. transcaucasicus Tanasevitch, 1990 . They all share the highly enlarged and ventrally pointing anterior radical process (ARP, Figs 3, 4, 12 ) and the paired inner longitudinal narrow lobes of the epigyne ( Figs 8, 11 ). The Mediterranean species also have a massively broadened radical tailpiece tip with an inner thickening ( Fig. 4 ). With the exception of Diplocephalus guidoi n. sp. the Mediterranean species have a double folded prolateral tibial apophysis, a retrobasal striated glabrous bump emerging from the cymbium ( Fig. 12 ) and the retrolateral side of the anterior radical process bears striations ( Fig. 12 ). The males of all these species have a distinct PME-lobe while Diplocephalus guidoi n. sp. has a small post PME-lobe ( Fig. 1 ). Post PME-lobes are among the rarest types of cephalic lobes in erigonines. The new species is the only Diplocephalus known to have a post PME-lobe.

Figures

FIGURES 1 – 13. Diplocephalus guidoi n. sp. (NMBE Ar 7251, paratypes) (1 – 10) and D. arnoi (11 – 13). Prosoma lateral male (1), female (2). Male palp retrolateral (3, 12), prolateral (4); embolic division distal (5); male tibia retrolateral (6), dorsal (7, 13). Epigynum ventral (8, 11), aboral (9), dorsal (10). Scale bars: figs 1 – 2: 1.0 mm; figs 3 – 13: 0.02 mm. See previous page for abbreviations.