Theridion himalayana Priyadarshini & Tripathy sp. nov.

Type material.

Holotype ♀ (ZSI /EBRC/Ar-18540), from India: Uttarakhand, (30.473531°N, 79.1696°E), 2207.15 m above sea level, 06. 8. 2024, Coll. A. Tripathy.

Paratypes: 2 ♀ (ZSI /EBRC/Ar-18541) data same as holotype, 15. 8. 2024.

Etymology.

The specific epithet ‘ himalayana’ is assigned to species owing to the locality from which it was first found as an ode to the mighty Himalayan Mountain range that holds a wealth of biodiversity.

Suggested common name.

Himalayan Happy-Face Spider.

Diagnosis.

Theridion himalayana sp. nov. can be readily distinguished from other Indian congeners by the unique configuration of the copulatory ducts (CD) and fertilisation ducts (FD). In T. himalayana sp. nov., the CD is elongate, strongly curved, and prominently protruding forward, with both ducts running almost parallel before terminating downward. The CD which is longer than the spermathecae exhibits a distinctive sew-hook – like appearance, which is not observed in any other examined species. The fertilisation ducts are short, narrow, and directed upwards, diverging away from each other to form a V-shaped orientation. The FD arises below the spermatheca, with each duct directed opposite to the CD. This configuration clearly separates T. himalayana sp. nov. from T. odisha, which has a S-shaped, coiled CD that terminates in oval loops and FD inclined towards each other; T. bengalensis, where CD is short, slender, and directed away from each other, while FD appears tapering distally and directed away from spermatheca; T. melanostictum, characterized by extremely long, highly coiled CD and downward-directed, sickle-shaped FD; T. zonulatum, which possesses short, uncoiled CD and looped FD directed upwards.

Theridion himalayana sp. nov., which resembles Theridion grallator the most with respect to general morphology and colour pattern, can be easily distinguished apart by the structure of genitalia of both male and female individuals. T. grallator has short, curved CD which converges only at the opening and a FD that runs parallel to the spermathecae whereas the combination of hook-shaped, downward-terminating copulatory ducts and short, upward-directed fertilisation ducts is diagnostic for Theridion himalayana sp. nov. Although genitalia were found not to be similar, morphology of the spider along with abdominal patterns came closest to T grallator as none of the other congeners exhibited polymorphism. A detailed comparison of genitalia and related characters has been presented in the table below (Table 3).

Description.

Female (holotype).

Measurements. Total length – 2.94 mm, Carapace length – 1.17 mm, width – 0.94 mm. Abdomen length – 1.77 mm, width – 1.00 mm, Leg I – 3.47 / 0.44 / 2.84 / 4.24 / 0.89, Leg II – 2.32 / 0.31 / 1.54 / 2.15 / 0.70, Leg III – 1.42 / 0.30 / 0.82 / 1.19 / 0.49, Leg IV – 2.92 / 0.38 / 2.05 / 2.77 / 0.70.

Small-sized, greenish-yellow spider (Fig. 3 B).

Cephalothorax: Carapace translucent yellow with radiating green hues from the centre with a minor fovea (Fig. 4). Clypeus and chelicerae are clear without any markings. AME, PME, ALE and PLE are all the same size and diameter (Fig. 4 A). Fangs brown and smooth (Fig. 4 B) In lateral view, the cephalothorax is flat, eye region raised as depicted in Fig. 4 C. Dorsally, the eye region is surrounded by 9 setae i. e., 2 between PME and AME, 1 on each side between the PLE and PME, 2 posterior to PLE on each side and 1 present distally between the PME. This combined forms an elliptic ring like arrangement (Fig. 5 B). Also, a 5 setae arrangement distally to the elliptical arrangement in the centre of the cephalothorax and anterior to the fovea is present.

Abdomen: In lateral view, flat from the dorsum and rounded with a red blob in the anterior dorsum surround by a white ring. Distally five black spots surrounded by white spots in a ‘ V’ shape are present (Fig. 5 A). Laterally covered with more pronounced white hairs than the ventral and dorsal region (Fig. 5 B).

Epigynum: Loop like rounded in structure, small, like ‘ Sew Hook’ shape (Fig. 5 C, E). Copulatory duct longer than spermatheca length. External genitalia protruding flap like overhanging on a minor depression in the epigynal region (Fig. 5 D). Spermatheca oval and slightly tapering posteriorly at the junction of CD (Fig. 5 F, G).

Legs: Legs slender, translucent, light yellowish, straw coloured with black to brown, discrete rings on femora, tibia distally brown, metatarsus apically darker (Fig. 6 A). The first and fourth pair of legs have black spots at the tarsal – tibial and femur-tibia joints, where the one between tibia and metatarsus id are most prominent while the rest are faintly visible. The other two legs also have similar black marks but are sometimes absent or very faint.

Leg Formula: I> IV> II> III

Spinnerets: Spinnerets same as body colour, light yellowish white protruding outwards from abdomen. Not very distinct in colour but raised from the surface of the abdomen; Arrangements of spigots on ALS, PMS, PLS like that of other Theridiinae (Fig. 7 A – F). About 35–40 piriform spigots (PI) on ALS (Fig. 7 D). One cylindrical spigot on PMS (Fig. 7 C) each with short base. Flagelliform spigot on PLS longer than its cylindrical spigot length. Two acini-form spigots on PMS. Shaft of minor ampullate spigot longer than cylindrical spigot on PMS.

Sensilla: Six sensillar structures were present on all the legs namely trichobothria, mechano-sensory setae, lyriform organ, slit organ and trichoidea sensilla (Fig. 8 A – E). The tarsal organ was only found on the pedipalp of the male. Tarsal comb with elevated base, straight serrations, distinctly notched (Fig. 6 C, D) typical to that of Theridiinae (Agnarsson 2004) was reported.

Male (Paratype).

Measurements. Total length — 2.23 mm, Carapace length – 0.99 mm, width – 0.88 mm. Abdomen length – 1.24 mm, width – 0.52 mm, Leg I – 4.01 / 0.42 / 3.27 / 4.84 / 0.92, Leg II — 2.87 / 0.39 / 2.14 / 3.01 / 0.77, Leg III – 1.67 / 0.27 / 1.1 / 1.48 / 0.51, Leg IV — 3.23 / 0.36 / 2.45 / 3.48 / 0.74, Palp – 0.64 / 0.16 / 0.16 / - / 0.49; Total Palp length – 1.45 mm.

The description of the cephalothorax and legs of the male is similar as that of the female. The males have a smaller body but relatively longer legs and narrower abdomen (Figs 3 A, 9 A). The setae and eye arrangements are depicted in Fig. 10 A, B.

Abdomen: In lateral view, flat from the dorsum and rounded. One red blob is segregated in the middle towards the anterior side of the abdomen, supported by a black patch at the base. In dorsal view, four large spots, two on each side and two small at the distal end of the abdomen, are present. In some morphs only five spots are visible instead of six.

Palp: Conductor mostly membranous, folded along length, broader and chitinous apically (Fig. 9 A – C). Embolus not exceeding conductor length (Fig. 9 B – E), broader at base, narrow apically (Fig. 9). Tegulum and Sub Tegulum separated by thin margin (Fig. 9 C).

Sensilla: The whole body, the first pair of legs, and the pedipalp of a male (T. himalayana sp. nov.) were used to detect the External Sense Organs (ESOs) using SEM. Six types of sensilla structures were found (Fig. 8).

Distribution.

Known only from the type locality (Uttarakhand, India) (Fig. 2).