Diplocephalus komposchi, Milasowszky, Norbert, Bauder, Julia & Hepner, Martin, 2017

Milasowszky, Norbert, Bauder, Julia & Hepner, Martin, 2017, Diplocephalus komposchi n. sp., a new species of erigonine spider (Araneae, Linyphiidae) from Austria, Zootaxa 4268 (2), pp. 296-300 : 297-299

Diplocephalus komposchi new species ( Figs. 1–12 )

Material examined. Holotype. AUSTRIA: Carinthia: Bezirk Völkermarkt: Feistritz ob Bleiburg : Petzen : summit between “ Knieps ” and “ Feistritzer-Spitz ”, 30 m below the summit on the north-side , 2.095 m above sea level [E 14 ° 45’22”, N 46 ° 30’21”], fine rock debris, soil with humus layer, cushion plants, at foot of the rock cliff, 1 male, 28.VII–8.IX.2009, pitfall trap BFPE 19C, leg. Ch. & B. Komposch [at NHMW 27.619 ]. Paratypes . AUSTRIA: One female (allotype), same locality data and date as holotype [at NHMW 27.620 ] ; Carinthia: Bezirk Völkermarkt: Feistritz ob Bleiburg: Petzen: same locality as holotype, fine rocky debris, soil with humus layer, cushion plants, at foot of the cliff wall, 1 male, 28.VII–8.IX.2009, pitfall trap BFPE 19 E, leg . Ch. & B. Komposch [at NHMW 27.621 ] ; Petzen: same locality as holotype, in a steep rock cliff, 1 male, 28.VII–8.IX.2009, pitfall trap BFPE 19 I, leg . Ch. & B. Komposch [at NHMW 27.622 ] ; Petzen: same locality as holotype, in a steep rock cliff, 1 male, 28.VII–8.IX.2009, pitfall trap BFPE 19 K, leg . Ch. & B. Komposch [at NHMW 27.623 ] .

Additional material examined. AUSTRIA: Carinthia: Bezirk Völkermarkt: Feistritz ob Bleiburg : Petzen : same locality as holotype, fine rock debris, soil with humus layer, in a crevice of a vertical cliff below an overhanging rock, 1 male, 28.VII–8.IX.2009, pitfall trap BFPE 19 B, leg. Ch. & B. Komposch [at ChK].

Etymology. The species name is a noun in apposition honoring the Austrian arachnologist Christian Komposch, who is the collector of all material.

Diagnosis. Diplocephalus komposchi n. sp. can be distinguished from other species in the genus by (i) the condition of the bisected ventral epigynal plate ( Figs. 2, 3 ), in which a triangular area of the dorsal plate is visible at three quarters length of the ventral plate ( Fig. 2 ); (ii) the particular arrangement of the vulva features, i.e. spermathecae, copulatory and fertilization ducts ( Fig. 3 ); and (iii) the presence and shape of two peculiar projections on the male prosoma ( Figs. 4, 5 ). Unfortunately, all palps of the new species were found in expanded condition, which makes it impossible to provide a clear identification based on palpal features alone. The position and form of the spermathecae resemble that of Diplocephalus pseudocrassilobus Gnelitza 2005 . The shape of the male tibial apophysis resembles that of Diplocephalus crassilobus . However, D. komposchi n. sp. lacks the lateral teeth, which originates from the ARP in D. crassilobus . Although the tibial apophysis is also similar to that of D. helleri and D. protuberans , we doubt that there is a close relationship to either of these species due to differences in the shape of the embolus.

Description. Holotype male ( Figs. 4–8 , NHMW 27.619). Additional MCT images were taken from male paratype from site 19E ( Figs. 9–12 , NHMW 27.621). Total body length 2.14. Cephalothorax/Prosoma smooth; brown with some darker markings; 0.96 long, 0.74 wide; with two large lobe-like projections ( Figs. 4, 5 ) which are divided by a transverse groove, the anterior lobe is biconcave, the posterior lobe is finger-shaped ( Figs. 4, 5 ); small grooves slightly above PLE; clypeus smooth. AME the smallest, located on tip of anterior lobe, ALE, PME and PLE oval of nearly equal sizes, PME on posterior lobe, about its diameter from tip, ALE and PLE very close to each other. Chelicerae with stridulatory organ; five promarginal teeth, three retromarginal denticles. Sternum smooth, brown; 0.54 long, 0.54 wide. Legs yellow-brown; coxae apically dark. Tibial spine formula 2:2:1:1; TmI 0.54 (left), 0.48 (right). Pedipalp yellow-brown, tibia and cymbium brown, patella length/width ratio = 4. Tibia with one retrolateral and one prolateral trichobothrium, prolateral tibial apophysis prominent. Protegulum present; suprategular apophysis deriving from the suprategulum with marginal apophysis, distal apophysis and inner apophysis; the inner suprategular apophysis is bifurcate, consisting of a large and a small branch. Embolic division complex, embolus short, with pointed tip, mostly covered by an embolic membrane; anterior radical process distinct, clearly curved; radical tailpiece with broad tip.

Female allotype ( Figs. 1–3 ): Total length 1.96. Cephalothorax/Prosoma smooth, dark brown; 0.86 long, 0.64 wide; clypeus smooth. Posterior eye row straight, anterior row slightly procurved, AME the smallest, separated by their diameter, PLE and PME of equal size, PME separated by nearly half their diameter, ALE larger, oval. Chelicerae with stridulatory organ, five promarginal teeth, four retromarginal denticles. Sternum smooth, dark brown; 0.48 long, 0.48 wide. Legs yellow-brown; coxae apically dark. Tibial spine formula 2:2:1:1; TmI 0.52 (left), 0.50 (right). Ventral epigynal plate longitudinally bisected. Anteriorly, ventral epigynal plates directly adjoining each other, leaving only a small fissure at ¼ of its length. Posteriorly, ventral epigynal plates diverging, showing a triangular part of dorsal plate with nearly straight lateral margins. The height of this isosceles triangle is almost twice the length of its base. Anteriorly, a distinct rim is visible. Horizontal middle part of anterior rim almost the same length as triangle base. Vulva with one pair of oblong spermathecae, copulatory ducts and fertilization ducts arise independently, fertilization duct mesally oriented.

Taxonomic remarks. We were unable to match the newly discovered species with other Diplocephalus species on the basis of illustrations in the literature. In males, the shape of the two lobes on the prosoma are distinct features; however, there is slight variation in the length of these head projections, as well as in the angle between them and in their angle relative to the prosoma. Referring to the findings of Frick et al. (2010), Diplocephalus komposchi n. sp. is clearly a true member of the Savignia -group, since it possesses a bisected epigynum.

Distribution, habitat and phenology. Diplocephalus komposchi n. sp. is known only from the “Petzen” area in Carinthia ( Austria) ( Figs. 13A , B). The habitat of this new species is characterized by fine to coarse rock debris, rock crevices and cliffs, soil with small humus layer, and sparse vegetation with cushion plants ( Fig. 13 B). Males were found between 28.VII–8.IX.2009. The single female specimen was also found in the same sampling period. Most probably reproduction occurs during the ice and snow free period between July and November. Considering the occurrence of D. komposchi n. sp. in close vicinity to the Slovenian border we anticipate future records from Slovenia, as well.

Figures

FIGURE 13. A, Geographic position of the type locality (black dot) of Diplocephalus komposchi n. sp. in Austria (AT) at the border to Slovenia (SI). B, Locality of Diplocephalus komposchi n. sp. in the “ Petzen ” area; view from the “ Kniepssattel ” towards WNW showing the peaks “ Knieps ” and “ Feistritzer Spitz ” [Photo: Christian Komposch, 8 September 2009].

FIGURES 1 – 8. Diplocephalus komposchi n. sp. 1 – 3, Female allotype; 4 – 8, male holotype. 1, Female prosoma lateral. 2, Epigynum, ventral. 3, Epigynum, dorsal. 4, Male prosoma, lateral. 5, Ditto, dorsal. 6, Male tibia, dorsal. 7, Expanded male palp. 8, Embolic division, distal. Scale bars, 1, 4, 0.5 mm; 2 – 3, 0.2 mm; 5, 0.5 mm; 6 – 7, 0.25 mm; 8, 0.1 mm.

FIGURES 9 – 12. Micro-computed tomographic (MCT) images of the dissected palp of Diplocephalus komposchi n. sp. 9, Male paratype. 10, Tegulum and subtegular division and embolic division combined. 11, Embolic division. 12, Tegulum and subtegular division. Scale bars, 9, 0.1 mm; 10 – 12, 0.1 mm.