Aetius O. Pickard-Cambridge, 1896

Dankittipakul, Pakawin & Singtripop, Tippawan, 2013, First description of the male of the little-known ant mimicking spider genus Aetius O. Pickard-Cambridge (Araneae: Corinnidae), Revue suisse de Zoologie 120 (4), pp. 575-583 : 576-577

Aetius O. Pickard-Cambridge, 1896

TYPE SPECIES: A. decollatus O. Pickard-Cambridge, 1896 , by monotypy.

DIAGNOSIS: Aetius can be easily differentiated from other castianeirine genera by a combination of characters: Posterior portion of prosoma protruding, forming a blunt projection hanging over pedicel (Figs 1-2, 8) (other castianeirines and trachelines have a tubular projection connected to the pedicel); prosoma relatively flat in females, in male convex, with a broad central plateau which abruptly slopes towards the margin (Figs 1-5, 8); similar to Serendib and Sphecotypus in having a strongly recurved PER (Fig. 8), distinguished from Serendib by the broad carapace widest at two thirds of its length and by the absence of paired anterior dorsal spines on the opisthosoma (Figs 2-5, 8) (carapace elongate-oval, 1-2 pairs of conspicuous spines present on the opisthosoma in Serendib ); distinguished from Sphecotypus by lacking a deep excavation behind the cephalic region.

The shape of the tegulum in Aetius conforms well to the typical palpal morphology of Castianeirinae males and it is characterized as follows: 1) The pyriform tegulum is distinctly narrowed distally (Figs 12-17). 2) The embolus is situated apically (Deeleman-Reinhold, 2001). 3) The subtegulum is generally located retrolaterally (Figs 12, 16) ( Haddad, 2004; Reiskind, 1969). However, Bosselaers & Jocqué (2002) described the subtegulum of Castianeirinae as prolaterally and retrolaterally protruding (character 142: 2, found in Copa spp. ). This is also the case in Aetius where a poorly defined prolateral part (Fig. 13) and a small retrolateral protrusion of the subtegulum can be seen (Fig. 12; see also Bosselaers & Jocqué, 2002: 250, fig. 3E). 4) A small retrolateral tibial apophysis is present. Although the absence of the tibial apophysis is considered a synapomorphic character shared among males of the Castianeirinae (Deeleman-Reinhold, 2001; Haddad, 2004; Reiskind, 1969), some species of Asian genera, including Aetius (Fig. 15), Medmassa , Serendib , Sphecotypus , do retain a retrolateral tibial apophysis. 5) A deep and wide depression is situated on the ventral surface of the palpal tibia (Figs 13, 16-17). 6) The sperm duct is strongly convoluted (Figs 12, 16). The latter two characters can also be found in males of Serendib . 7) A deep basal notch is found in the retrolateral margin of the cymbium (Fig. 15), a character so far only known in Aetius .

In all females of Aetius the heavily sclerotised epigyne (Figs 9-10) has a pair of rounded copulatory orifices located medially or posteriorly, the insemination ducts are short, and the large, oval spermathecae are simple, without bursae (Figs 11, 18). In most castianeirines the bursae are indistinct and fused with the spermathecae (Deeleman-Reinhold, 2001). These two structures are represented by a convoluted, thick-walled tube with an anterior enlargement in Pranburia , Castoponera , Corinnomma , and Apochinomma , whereas in Aetius and Serendib the posterior portion of this structure is a simple, straight tube.