Chikunia nigra, (O. PICKARD-CAMBRIDGE, 1880)

Smith, Cassandra, Cotter, Addie, Grinsted, Lena, Bowolaksono, Anom, Watiniasih, Ni Luh & Agnarsson, Ingi, 2019, In a relationship: sister species in mixed colonies, with a description of new Chikunia species (Theridiidae), Zoological Journal of the Linnean Society 186, pp. 337-352 : 341-345

CHIKUNIA NIGRA (O. PICKARD-CAMBRIDGE, 1880)

Originally, Argyrodes nigra O. Pickard-Cambridge, 1880 . Later placed in Theridion by Simon (1905), Theridula by Saito (1935) and Chrysso by Levi (1962). Transferred here by Grinsted et al. (2012).

Material examined

Types from Sri Lanka (Thwaites’s Ceylon collection), not examined. Multiple male and female specimens from northern central Bali, near lake Buyan ,

0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0

a p p r o x i m a t e l y 8.2 4 3 6 9 3° S, 1 1 5. 1 0 4 0 7 0 °E t o 8.282064°S, 115.164817°E ( Fig. 3), collected in July 2017. Five specimens from Sri Lanka and India (see Grinsted et al., 2012) were also re-examined .

Diagnosis

Chikunia nigra differs from other Chikunia species in the long, tapering male abdomen, conformation of male palp ( Figs 6J, 7J, 8) with very long embolus and large conductor, and in the epigynum with oval spermathecae and simple non-spiralling copulatory ducts. Furthermore, C. nigra females are distinct by having both pedipalps and tarsus of leg I black or very dark brown in colour ( Fig. 6A, C), in contrast to the remaining leg segments, which are pale white or yellow in colour.

Redescription

Female (from Bali, Indonesia): Legs I–IV. Total length 3.54 mm. Cephalothorax 1.11 mm long, 0.91 mm wide, 0.71 mm high, medium to dark brown with tan markings laterally. Chelicerae are dark brown in colour. Sternum 0.69 mm long, 0.56 mm wide, extending halfway through coxae IV, medium brown. Abdomen 2.43 mm long, 2.55 mm wide, 1.77 mm, subtriangular in shape and tapering towards posterior ( Fig. 6A–C). Wide dark brown patch and scattered spots occur dorsally along abdomen ( Fig. 6A–C). Eyes approximately equal in size anterior lateral eyes ( ALE) 0.06 mm, anterior median eyes ( AME) 0.08 mm in diameter. All eyes within one eye diameter apart from each other excluding the anterior median, which are 0.12 mm apart. Leg I femur 1.70 mm, patella 0.40 mm, tibia 1.0 mm, metatarsus 1.10 mm and tarsus 0.61 mm. All legs tan in colour; tarsus of leg I dark brown ( Fig. 6A, C). Leg formula 1423. Epigynum simple, translucent cuticle, with tiny copulatory openings, leading to oval spermathecae ( Fig. 6D–F).

Male (from Bali, Indonesia): Total length 2.32 mm. Cephalothorax 0.83 mm long, 0.71 mm wide, 0.53 mm high, dark brown to black in colour with faint medium brown broad patches dorsally, relatively slender and tapering towards end ( Fig. 6G–I). Sternum 0.60 mm long, 0.47 mm wide, dark brown. Abdomen 1.49 mm long, 0.81 mm wide, 0.72 mm high, black in colour. Eyes approximately equal in size, ALE 0.07 mm, AME 0.08 mm in diameter. All eyes within one eye diameter apart from each other excluding the anterior median, which are 0.12 mm apart. Leg I femur 1.60 mm, patella 0.31 mm, tibia 0.95 mm, metatarsus 0.74 mm and tarsus 0.46 mm. All legs dark brown with white coxae and white coloration where trochanter and femur meet. Leg formula 1423. Male palps with prominent and long embolus, spiral covering outer edge of tegulum, distally supported by a large conductor.

Variation: Female total length 2.01–3.54 mm, femur I 1.11–1.70 mm; male total length 2.32–3.20 mm, femur I 1.37–1.98 mm. Female abdomen shape and coloration vary greatly ( Fig. 9A–I). Colours range from pale orange to reddish orange, amber, various shades of brown, greenish grey and black. Some abdomens are uniformly coloured, whereas others have a nondistinct, mottled black pattern of varying size in the centre of the abdomen. Abdomen shape varies from having rather large abdominal humps and a short, pointy rear end (abdomen wider than long, similar to C. bilde ) to a more slender look with smaller abdominal humps and a longer, tapering rear end (abdomen longer than wide).

CHIKUNIA BILDE SMITH, AGNARSSON & GRINSTED