Gasteracantha Sundevall, 1833

Tan, Ji, Chan, Zi Yang, Ong, Ching Ang & Yong, Hoi Sen, 2019, Phylogenetic relationships of Actinacantha Simon, Gasteracantha Sundevall, Macracantha Hasselt and Thelacantha Simon spiny orbweavers (Araneae: Araneidae) in Peninsular Malaysia, Raffles Bulletin of Zoology 67, pp. 32-55 : 43

Genus Gasteracantha Sundevall, 1833

According to Dahl (1914) and Pickard-Cambridge (1879), members of the genus Gasteracantha are characterised by a cephalothorax that is no longer than broad and strongly arched in the front but flattened in the posterior half and covered by the anterior part of the abdomen. The abdomen is composed of a chitin skin armed with 2–6 spines arising from different points of the abdominal margin. The abdomen is marked with sigilla (previously called sigil or ocelli) on the upperside (and occasionally underside) which are likely points of attachment of muscular fibers ( Pickard-Cambridge, 1879). Four of the sigilla form a trapezoid pattern at the middle of the abdomen while the others are around the edge. There are generally two transverse rows of sigilla at the rear edge of the abdomen although the most posterior row often occurs within the posterior abdominal fold in some species and is thus invisible. Dahl (1914) reported that the epigynum was hardly usable as a morphological character as (i) it often displays fewer tangible features; and (ii) it is variable depending on duration since the ultimate molt. However, Chrysanthus (1959, 1971) advocated the examination of the epigynal structures in species identification and have illustrated numerous reproductive structures of Gasteracantha spp. from New Guinea. In this study, the epigynal structure was shown to be valuable information in species identification, especially between closely related species.