Australoechemus vickyae, Sherwood & Marusik & Sharp & Ashmole, 2023

Sherwood, Danniella, Marusik, Yuri M., Sharp, Adam & Ashmole, Philip, 2023, A survey of Gnaphosidae (Arachnida, Araneae) from Ascension Island with description of a new species of Australoechemus Schmidt & Piepho, 1994, African Invertebrates 64 (3), pp. 291-302 : 291

Australoechemus vickyae sp. nov.

Figs 1 , 2 , 3 , 4

Material examined.

Holotype: Ascension Island • 1♂; Boatswain Bird Island ; -7.936, -14.307; 12-31.IX.1957; E. Duffey leg.; No. 91; NHMUK.

Paratypes: Ascension Island • 1♀; Boatswain Bird Island ; -7.936, -14.307; 12-31.IX.1957; E. Duffey leg.; [no number]; NHMUK • 1♀; Boatswain Bird Island ; -7.936, -14.307; 12-31.IX.1957; E. Duffey leg.; No. 35; NHMUK • 1♀; Boatswain Bird Island ; -7.936, -14.307; 12-31.IX.1957; E. Duffey leg.; No. 51; NHMUK • 1♂, 1 immature ♂; Boatswain Bird Island ; -7.936, -14.307; 12-31.IX.1957; E. Duffey leg.; No. 65; NHMUK • 1♀; Boatswain Bird Island; -7.936, -14.307; 26-27.V.1995; P. Ashmole and M. Ashmole leg.;? Nodocion sp. det. J. A. Murphy; Murphy collection No. 23865; MMUE G7572.13477 • 1♀; South Gannet Hill , Ascension Island; -7.983, -14.399; 15.V.2013; pitfall trap; L. F. White leg.; ASC01604 • 1♀; near English Bay Road , Ascension Island; -7.913981, -14.378077; 85 m. a.s.l; pitfall trap; 13/01/2022; A. Sharp leg.; ASC F13 2 PFJ .

Diagnosis.

Australoechemus vickyae sp. nov. somewhat resembles A. celer , but males can be distinguished by having the retrolateral tibial apophysis almost as long as tibia, tapering at the tip and non-bifurcated (vs. shorter than tibia, broad at tip and bifurcated). Females of A. vickyae sp. nov. differ from those of A. celer by having the epigynal fovea widest in anterior part (vs. wider in midpart) and having receptacles smaller than the bursa copulatrix (vs. receptacles larger than bursa copulatrix).

Etymology.

The specific epithet is a matronym in honour of British conservationist and entomologist Vicky Wilkins (Species Recovery Trust, Salisbury, UK, and co-chair of the IUCN SSC Mid-Atlantic Islands Invertebrate Specialist Group) for her enduring and significant contributions to the conservation of invertebrates in the United Kingdom Overseas Territories.

Description.

Male (holotype). Total length: 6.17. Carapace: 2.67 long, 2.12 wide. Abdomen: 2.89 long, 1.75 wide. Leg measurements: I 8.12 (2.28, 1.05, 2.02, 1.63, 1.14), II 8.00 (2.28, 1.03, 1.44, 1.93, 1.32), III 7.49 (2.21, 0.87, 1.24, 1.85, 1.32), IV 11.02 (2.36, 1.56, 2.39, 3.28, 1.43). Setation: for legs see Table 1 . Colour (in alcohol): overall light brown, abdomen slightly darker than carapace, chelicerae and legs (Fig. 1A, B ). Chelicera with three promarginal teeth and one retromarginal tooth (Fig. 2A ). Eyes: AME largest, PME not reduced in size (Fig. 2B ).

Palp (Figs 3A , 4A-D ).

Patella longer than tibia, about 2 × longer than wide; tibia about 2 × longer than wide with non-bifurcated retrolateral apophysis gradually tapering toward tip, tip slightly bent prolaterally; cymbium elongate, gradually tapering, 2.2 × longer than wide; bulb oval, 1.8 × longer than wide, with very long subtegulum (St); sperm duct (Sd) U-shaped, retrolaterally as wide as tibial apophysis, gradually tapering prolaterally; anteroprolateral part of tegulum with elongate tegular anteroprolateral membranous lamellar extension (Al); conductor (Co) small, membranous, located near tip of embolus; embolus (Em) originates at about 9 o’clock position, straight, tip slightly bent. Palpal setation: femur d 0-1-4 r0-1-0 p0-1-0; patella d0-0-1; tibia d1-1-0.

Female (paratype). Total length: 8.27. Carapace: 3.53 long, 2.62 wide. Abdomen: 3.67 long, 2.63 wide. Leg measurements: I 8.96 (2.02, 1.63, 1.87, 1.98, 1.46), II 8.79 (2.01, 1.65, 1.72, 1.96, 1.45), III 8.29 (1.17, 1.38, 2.19, 2.00, 1.55), IV 11.42 (3.03, 1.82, 2.66, 2.57, 1.34). Setation: for legs see Table 2 , palp: femur d0-1-2 r0-1-0 p0-1-0; patella p0-1-0 r0-1-0; tibia d1-1-1 p0-2-1; tarsus d2-0-0 p2-1-0. Colour (in alcohol): carapace and legs light brown, abdomen beige, chelicerae reddish-brown (Figs 1C, D , 2C ). Chelicera with three promarginal teeth and one retromarginal tooth (Fig. 2C ). Eyes: AME largest, PME not reduced in size (Fig. 2D ).

Epigyne.

Epigynal plate almost as long as wide, with large fovea and distinct anterior hood (Ah); fovea widest anteriorly, posterior part 2 × thinner than anterior; bursa copulatrix (Bc) oval, longer than wide, spaced by about ½ of length; receptacles (Re) oval, transversal, locate at posterior margin of endogyne, spaced by about one width (Fig. 3B, C ).

Total length variation.

6.17-7.37 (adult males, n=2); 8.25-9.24 (adult females; n=6).

Distribution.

Known only from Ascension Island, South Atlantic Ocean.

Remarks.

The holotype and most of the paratypes were collected from Boatswain Bird Island, an islet which hosts several unique endemic arachnids ( Ashmole and Ashmole 2000). The paratype used for description is the unnumbered female in the Duffey collection, and it has also been clearly marked as the female used in the description on a newly added type label by DS. Two paratype females were collected recently on the mainland, indicating this species occurs more widely on Ascension. Eric Duffey was a prolific collector who collected all over the main island and Boatswain Bird Island ( Stonehouse 1960; PA pers. obs.). Fortunately, the type specimens of A. vickyae sp. nov. collected by Duffey were explicitly collected by him only from Boatswain Bird Island (as " Drassodes spp." in Duffey 1964) enabling us to be sure of their collecting locality. This species represents an interesting new record of a genus only thought to occur in the Cape Verde Islands previously ( WSC 2023). Molecular work in the future could further elucidate the higher-level relationships of this genus to other gnaphosids. Nonetheless, the morphology of the new species clearly favours placement in Australoechemus under its current definitions for the following reasons: (1) the similar shape of the tegular anteroprolateral membranous lamellar extension, the shape of the cymbium, the U-shaped sperm duct, and the absence of a scutum in the male, (2) the epigyne with a large fovea and distinct anterior hood in the female and (3) the presence of a trochanteral notch in both sexes.

Figures

Figure 1. Habitus of Australoechemus vickyae sp. nov. A holotype male, dorsal B ibid, ventral C paratype female, dorsal D ibid, ventral. Scale bars: 1 mm.

Figure 2. Ventral face of chelicera and eye pattern of Australoechemus vickyae sp. nov. A holotype male, chelicera B holotype male, eye pattern C paratype female, chelicera D paratype female, eye pattern. Scale bars: 1 mm.

Figure 3. Copulatory organs of Australoechemus vickyae sp. nov. A holotype male palp, ventral, structures traced B paratype female epigyne (cleared), ventral C ibid, endogyne (cleared), dorsal. Abbreviations: Ah = anterior hood, Al = tegular anteroprolateral membranous lamellar extension, Bu = bursa copulatrix, Co = conductor, Em = embolus, Re = receptacle, Sd = sperm duct, St = subtegulum. Scale bars: 0.5 mm (B, C).

Figure 4. General views of palp of holotype of Australoechemus vickyae sp. nov. A ventral B retrolateral C prolateral D dorsal. Scale bars: 1 mm.