Acusilas coccineus Simon 1895
Creators: name: Sankaran, Pradeep M.
name: Sebastian, Pothalil A.
Publisher: name: Zenodo
Year: 2018
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Arachnida
Araneae
Araneidae
Acusilas
Acusilas coccineus

description: Acusilas coccineus Simon, 1895 (Figs 1–3)
Acusilas coccineus Simon, 1895: 785 (Description of female); Uyemura, 1939: 142, figs a–f (Illustration of female); Yaginuma, 1960: 59, fig. 58 (Illustration of female); Namkung, 1964: 37, fig. 23 (Illustration of female) [See World Spider Catalog for complete list].
Phonognatha vicitra Sherriffs, 1928: 183, figs 1–2 (Misidentification; description & illustration of female). Phonognatha vicitra
Sherriffs, 1928: INDIA: Karnataka: Kodagu/ Coorg: Siddapura/ Sidapur: Charlotte estate/division, W. R. Sherriffs leg.,
December, repository unknown, possibly BMNH, 7 females; not examined. Topotype specimens were examined. New
synonymy.
Additional specimens examined. INDIA, Kerala: Kollam: Kulathupuzha Forest Reserve, 8o54'6.37''N, 77o3'51.70''E, 134 m alt., 31 July 2013, M. S. Pradeep leg., from rolled dried leaf retreat in web, by hand: 1 female (ADSH 090903 A); Ernakulam, Kurisumudi in Malayatoor, 10o12'33.36''N, 76o30'08.85''E, 94 m. alt., 4 December 2013, M. S. Pradeep leg., from rolled dried leaf retreat in web, by hand: 1 female (ADSH 090903 B); Kottayam, Kanakappalam in Erumely, 9o27'16.08''N, 76o50'43.54''E, 101 m. alt., 23 August 2014, M. S. Pradeep leg., from rolled dried leaf retreat in web, by hand: 1 female (ADSH 090903 C); Trivandrum, Patani in Ponmudi, 8o45'35.79''N, 77o7'00.75''E, 920 m. alt., 0 4 October 2014, M. S. Pradeep leg., from rolled dried leaf retreat in web (males from the retreat of one of the females), by hand: 2 males, 3 females (ADSH 090903 D); Idukki, Kattappana, 9o45'24.61''N, 77o07'00.71''E; 900 m. alt., 2 April 2015, M. J. Mathew leg., from rolled dried leaf retreat in web, by hand: 10 females (ADSH 090903 E). Karnataka: Kodagu / Coorg, Siddapura/ Sidapur, Charlotte estate/division, 12o17'5''N, 75o50'50''E, 922 m. alt., 13 November 2017, M. S. Pradeep & Jimmy Paul leg., from rolled dried leaf retreat in web, by hand: 9 females (ADSH 090903 F).
Diagnosis. Males of A. coccineus can be distinguished from other congeners by the black and slender embolus with a truncated tip (E; Fig. 2A). Females can be separated from other members of the genus by an anteriorly wide epigynal septum (Se; Fig. 2D, F) (see Schmidt & Scharff (2008) for a proper differential diagnosis).
Redescription. Male (ADSH 090903 D; Figs 1C, 2C) in alcohol. Carapace, clypeus, chelicerae, sternum, labium, maxillae, legs olive-brown. Ocular area slightly black. Cheliceral promargin with four teeth, retromargin toothless; chelicerae basally provided with pro and retrolateral condyles (Fig. 2C). Opisthosoma nearly oval, creamy-white, hirsute; dorsum mottled with black patches and grayish spots; laterals and venter with black striations. Legs with black annulations. Body length 3.21. Carapace length 1.55, width 1.11. Opisthosoma length 1.66, width 1.32. Eyes diameter: ALE 0.07. AME 0.12. PLE 0.09. PME 0.10. Eye interdistances: ALE–PLE 0.02. AME–ALE 0.04. AME–AME 0.12. AME–PME 0.12. PME–PLE 0.13. PME–PME 0.10. Clypeus height at AME 0.04, at ALE 0.13. Length of chelicerae 0.66. Measurements of pedipalp and legs: Pedipalp 1.14 [0.34, 0.14, 0.14, 0.52], I 3.14 [1.01, 0.48, 0.73, 0.53, 0.39], II 3.07 [0.94, 0.45, 0.64, 0.60, 0.44], III 2.01 [0.65, 0.32, 0.37, 0.35, 0.32], IV 2.79 [0.88, 0.45, 0.60, 0.48, 0.38]. Leg formula: 1243. Pedipalp as in Fig. 2A–B.
Female (ADSH 090903 D; Fig. 1A–B) in alcohol. Like male, except the following. Carapace, clypeus, chelicerae, labium, maxillae, sternum, palpal segments, legs, spinnerets tan coloured. Cephalic groove prominent (Fig. 1B). Cheliceral promargin with four teeth, retromargin with three, 2nd promarginal tooth largest; chelicerae lack condyles. Opisthosoma oblong; dorsum with prominent dark patches on white folium. Body length 10.24. Carapace length 4.09, width 3.27. Opisthosoma length 6.15, width 4.46. Eyes diameter: ALE 0.14. AME 0.26. PLE 0.19. PME 0.22. Eye interdistances: ALE–PLE 0.03. AME–ALE 0.09. AME–AME 0.18. AME–PME 0.18. PME–PLE 0.28. PME–PME 0.17. Clypeus height at AME 0.10, at ALE 0.25. Length of chelicerae 1.54. Measurements of palp and legs: Palp 3.82 [1.24, 0.52, 0.78, 1.28], I 10.79 [3.28, 1.57, 2.44, 2.28, 1.22], II 10.04 [3.16, 1.51, 2.22, 2.04, 1.11], III 6.60 [2.08, 1.14, 1.34, 1.15, 0.89], IV 10.46 [3.24, 1.63, 2.29, 2.25, 1.05]. Leg formula: 1423.Genitalia as in Fig. 2D–E.
Variation. Female: Body length 7.52–13.31 (n = 25). The female genitalia show slight variations particularly in the shape of the median septum and the shape and orientation of the copulatory ducts (e. g. see Fig. 2D–G).
Justification of the synonymy. Sherriffs (1928) cited that P. vicitra had a narrow cephalon, which was separated from the thoracic part by a shallow groove. Females with narrow cephalon, which is clearly demarcated from the thoracic region by a prominent groove is one of the characteristic features of the genus Acusilas (Schmidt & Scharff 2008: fig. 6A; herein Fig. 1B, D). Specimens collected from the Charlotte estate/division show all the diagnostic features of the genus Acusilas: narrow cephalon clearly demarcated by a prominent cephalic groove (Fig. 1D), AME closer to ALE than to each other, strongly recurved PER and epigynum with a transverse rim (AR; Fig. 2F) (Schmidt & Scharff 2008). All these clearly indicate that P. vicitra is a misplaced species in Phonognatha and is indeed a member of Acusilas. According to Sherriffs (1928), the opisthosomal pattern of P. vicitra consists of laterally placed dark patches on a white folium, which is the opisthosomal pattern of A. coccineus (Schmidt & Scharff 2008; compare Fig. 1B, D with Sherriffs 1928: fig. 1). Further, detailed examination of the genitalia of P. vicitra (Fig. 2F–G) collected from the Charlotte estate/ division has all the diagnostic features of A. coccineus including anteriorly wide epigynal septum and copulatory ducts visible without clearing the epigynum. Based on these observations we regard P. vicitra as a junior synonym of A. coccineus.
Note. Schmidt & Scharff (2008: figs 8A, 9B–C, 17A) observed the occurrence of broken-off emboli (that function as mating plug) in the copulatory ducts of both Acusilas africanus Simon, 1895 and Acusilas malaccensis Murphy & Murphy, 1983 and suggested that such mating plug might be found in other Acusilas species also. In agreement with their opinion, an embolic mating plug was observed in the copulatory ducts of one of our female specimens (Fig. 1E, arrows) collected from the Charlotte estate/division. This is the first record of a mating plug in A. coccineus.
Distribution in India. Karnataka (Sherriffs 1928, present data), Kerala (present data), West Bengal (Roy et al. 2017) (Fig. 3). Roy et al. (2010) recorded Acusilas from the tea ecosystem of Assam. However they failed to identify their species and suggested that it might be A. coccineus. Due to uncertainty of species identification, their record is omitted here.
description: Published as part of Sankaran, Pradeep M. & Sebastian, Pothalil A., 2018, Phonognatha vicitra Sherriffs, 1928 - a taxonomic misidentification of the orb-weaving spider Acusilas coccineus Simon, 1895 (Araneae, Araneidae), pp. 391-395 in Zootaxa 4434 (2) on pages 391-393, DOI: 10.11646/zootaxa.4434.2.12, http://zenodo.org/record/1290532