Theridion zonulatum Thorell, 1890

Sankaran, Pradeep M., Malamel, Jobi J., Joseph, Mathew M. & Sebastian, Pothalil A., 2015, Theridion echinatum Gao & Li, 2014, a junior synonym of Theridion zonulatum Thorell, 1890 (Araneae, Theridiidae) with comments on its web architecture, Zootaxa 4007 (1), pp. 138-142 : 138-141

Theridion zonulatum Thorell, 1890

( Figs. 1 B–C, 2A–F, 3A–E)

Theridion zonulatum Thorell, 1890: 273 (Description of ♀)

Theridion zebrinusum Zhu, 1998: 165 , figs. 103 A–C (Description and illustration of ♀). Lapsus calami . Theridion zebrinusum Song, Zhu & Chen, 1999: 148, figs. 83 A–B (Illustration of ♀).

Theridion zonulatum Ehrler et al., 2014: 80 , figs. 1–6 (Re-examined the holotype; established a synonymy with T. zebrinusum ) Theridion echinatum Gao & Li, 2014: 100 , figs. 84A–B, 86A–D (Description and illustration of ♂),

[Holotype ♂, paratype ♂, both from China: Yunnan Prov.: Xishuangbanna, both without voucher numbers, deposited in the Institute of Zoology, Chinese Academy of Sciences in Beijing (IZCAS), types not examined]. New Synonymy.

Material examined: India, Kerala, Thrissur, Charpa (10o18'16.39''N, 76o34'47.27''E) in Vazhachal, 216 m. alt., Pradeep M. S. leg. 0 7 January 2014, by hand, 1 ♂, 3 ♀ ( ADSH 103110584A). India, Kerala, Ernakulam, Illithodu (10o11'55.94''N, 76o33'00.57''E) in Malayatoor, 24 m. alt., Pradeep M. S. leg. 0 9 December 2014, by hand, 2 ♂, 9 ♀ (6♀ with egg sacs), 3 juveniles ( ADSH 103110584B). India, Kerala, Trivandrum, Kallar in Ponmudi (8o45'35.79''N, 77o07'00.75''E, 920 m. alt.), Pradeep M. S. leg. 14 December 2014, by hand, 4 ♀, 2 juveniles ( ADSH 103110584C). India, Kerala, Kollam, Kulathupuzha Forest Reserve (8o54'06.37''N, 77o03'51.70''E), 134 m. alt., Pradeep M. S. leg. 11 January 2015, by hand, 1 ♂, 2♀, 2 juveniles ( ADSH 103110584D).

Diagnosis: T. zonulatum is most similar to T. cazieri Levi, 1959 , but can be separated from the latter by the following combination of characters: cymbium with a disto-dorsal macroseta (cymbium of T. cazieri lacks macroseta), median apophysis with beak-like tip and is lying almost parallel to theridiid tegular apophysis (in T.

cazieri , median apophysis with blunt tip and is lying not parallel to theridiid tegular apophysis), contiguous copulatory ducts (copulatory ducts in T. cazieri are widely separated), fertilization ducts lie close to copulatory ducts (in T. cazieri , fertilization ducts lie away from the copulatory ducts) (compare Figs 3 A–C, 3E with Levi, 1959b: figs 216, 218).

Male: ( Figs. 2 A, 2C–D,3A–C) For description of male, see Gao & Li (2014).

Female: ( Fig. 2 B) Body length 3. 33. Abdomen dorsally and laterally black with transverse white bands due to which the female is banded like a zebra. Legs with dark annulations. Cephalothorax length 1.02, width (at the middle) 1.04. Abdomen length 2.31, width (at the middle) 1.57. Eye interdistance: AME–AME 0.07. AME–PME 0.08. AME–ALE 0.03. PME–PME 0.12. PME–PLE 0.07. Clypeus height at AMEs 0.17, at ALEs 0.18. Measurements of palp and legs: Palp 1.24 [0.39, 0.20, 0.23, 0.42], I 7.56 [2.27, 0.61, 1.81, 1.92, 0.95], II 5.2 [1.66, 0.54, 1.06, 1.27, 0.67], III 3.86 [1.27, 0.39, 0.70, 0.93, 0.57], IV 6.34 [2.14, 0.60, 1.39, 1.51, 0.70]. Leg formula: 1423. Epigynum as in Figs. 2 E–F and 3D–E.

Justification of synonymy. The original description of T. echinatum is based on two adult male specimens collected from the Yunnan Province in China ( Gao & Li 2014). Although we did not examine the type of T. echinatum , good illustrations and images of this species are available ( Gao & Li 2014, figs. 84A–B, 85A–B, 86A– D). Comparison of male palp of T. zonulatum ( Figs. 2 C–D, 3A–C) with the original drawings and images of T. echinatum suggested that T. echinatum has all the diagnostic features of T. zonulatum including the general shape of the bulb, cymbium with a disto-dorsal macroseta (strong spine as in Gao & Li, 2014) and shape and orientation of conductor, embolus, median apophysis, and theridiid tegular apophysis. These observations confirmed that the two specimens belong to the same species. Though palpal sclerites such as median apophysis, theridiid tegular apophysis and embolic base of T. echinatum show slight variations in shape and size from that of our specimens, these differences, which we consider as intraspecific variation, are little and do not provide evidence for a separate species. The species T. echinatum should thus be regarded as a junior synonym of T. zonulatum .

Variation. Male body length (n = 4) 2.17–2.28. Female body length (n = 18) 3.30–4.01

Distribution in India. Kerala: Ernakulam (Malayatoor), Kollam (Kulathupuzha), Thrissur (Vazhachal), Trivandrum (Ponmudi). This is the first report of the species from India.

Web ( Figs. 1 A–D, 4A–B). T. zonulatum builds a complex ‘gumfoot-sheet web’ across the surface of green leaves ( Figs. 1 A–D). It can be a combination of Type 3 and Type 4 theridioid webs both are devoid of gumfoots. Type 3 or the Theridion - type web consists of supporting structure and viscid silk lines without gumfoots, while Type 4 or the Coleosoma - type web has a non-viscid sheet and a non-viscid knock-down trap without gumfoots ( Benjamin & Zschokke 2003). Structurally, the web of T. zonulatum consists of an upper layer of unequally spaced, parallel frame-lines forming the supporting structure, a middle expanded, bowl-shaped sheet with knockdown trap and a lower layer of irregularly scattered gum-foots ( Figs. 4 A–B). The number of supporting structures produced depends on the size of the leaf lamina selected for constructing the webs and the size of the sheet with knock-down trap formed depends upon the number of supporting structures produced (Sankaran, pers. observation). The supporting structures are being attached firmly to both the margins of the leaf lamina and are interconnected by viscid lines, which are arranged in a zig-zag fashion ( Fig. 4 A). Both the supporting structures and the viscid lines together form a flat ‘roof’ for the web. The non-viscid sheet, which is formed of closely woven silk threads, is hanging down from the ‘roof’ by means of the non-viscid knock-down trap. The lines forming the knock-down trap are attached to the sheet in such a way that the sheet appears to form an inverted, W-shaped bowl ( Figs. 1 D, 4B). The outer surface of the sheet is provided with numerous scattered gum-foots, which are attached to the leaf lamina and a median, longitudinal gum-foot free area for facilitating the free movement of the spider ( Fig. 4 B).

Figures

FIGURE 1. Theridion zonulatum Thorell, 1890 from Illithodu, Ernakulam. A, Male and female spiders (rectangles) on the same plant. B, Female with egg sac (arrow) in web. C, Male in web. D, View of the web. A – D Photos by Jimmy Paul.

FIGURE 2. Theridion zonulatum Thorell, 1890. A, Male habitus, dorsal view. B, Female habitus, dorsal view. C, Left male palp, ventral view. D, Same, retrolateral view. E, Epigynum, ventral view. F, Same, dorsal view. Scale bars: A, 0.5 mm; B, 1 mm; C – F, 0.2 mm.

FIGURE 3. Theridion zonulatum Thorell, 1890. A, Left male palp, prolateral view. B, Same, ventral view. C, Same, retrolateral view. D, Epigynum, ventral view. E, Same, dorsal view. Abbreviations: C, conductor; CD, copulatory duct; E, embolus; EB, embolic base; FD, fertilization duct; MA, median apophysis; ST, subtegulum; S, spermatheca; T, tegulum; TTA, theridiid tegular apophysis. Scale bars: A – C, 0.14 mm; D – E, 0.05 mm.

FIGURE 4. Web of Theridion zonulatum Thorell, 1890. A, ‘ Roof’ of the web formed of supporting structures and viscid lines. B, Sheet with knock-down trap and gumfoots. Abbreviations: GF, gumfoot; KN, knock-down trap; SH, sheet; SSt, supporting structure; Vsi, viscid line (Figures not to scale).