Eutittha Thorell, 1878

Esyunin, Sergei L. & Zamani, Alireza, 2020, ‘ Conundrum of esoterica’: on the long-forgotten genus Eutittha Thorell, 1878, with new taxonomic considerations in Cheiracanthium C. L. Koch, 1839 (Araneae: Cheiracanthiidae), Journal of Natural History (J. Nat. Hist.) 54 (19 - 20), pp. 1293-1323 : 1296-1299

Genus Eutittha Thorell, 1878 , stat. resurr.

Eutittha Thorell, 1878, p. 178 (originally monotypic, with type species Eutittha insulana

Thorell, 1878). Simon 1897, p. 87 (synonymy with Cheiracanthium ; here rejected).

Diagnosis and relationships

In addition to Eutittha , there are two more genera of Cheiracanthiidae that have the following combination of characters: (1) narrow cymbial fold stretches along the retrolateral margin and does not break the symmetry of the cymbium, (2) embolic base in apical-prolateral or apical position; (3) TA absent; (4) CD twisted around or in front of the spermathecae. These are the East Asian Calamopus Deeleman-Reinhold, 2001 and Summacanthium Deeleman-Reinhold, 2001 . Members of Calamopus ‘are adapted to living on the undersurface of green leaves in shady evergreen forest. They are elongate and greenish with flattened carapace and very long legs’ ( Deeleman-Reinhold 2001, p. 244). Eutittha well differs from Calamopus by short, not flexed cymbial spur and not reduced RTA of male palp, vs. ‘the palpal spur is flexed near the base and directed alongside the dorsal cymbium, pointing in anterior direction, whereas the tibial apophysis is reduced’ in Calamopus ( Deeleman-Reinhold 2001, p. 248) , and by copulatory ducts (CD) twisted around the spermathecae, vs. ‘upgoing and downgoing sections’ of CD are intertwined in Calamopus ( Deeleman-Reinhold 2001, p. 248) .

Species of Summacanthium are small (~ 3 mm), vs. medium-sized Eutittha (5–11 mm). Summacanthium ‘males with a scape-like protrusion on the venter, provided with lateral chitinized pits’ ( Deeleman-Reinhold 2001, p. 240), vs. Eutittha males without such protrusion. In addition, Summacanthium was collected in the canopy of the forests (Deeleman- Reinhold 2001), while Eutittha was found in open habitats ‘and do not occur in forest’ ( Dondale 1966).

Eutittha is also close to members of the crucigerum species group of Cheiracanthium (that includes at least two species: C. crucigerum Rainbow, 1920 from Norfolk Islands, Australia and C. wiehlei ; Chrysanthus, 1967 from Papua Province, Indonesia), which is diagnosed by a set of characters similar to those described above for Eutittha . Species of the crucigerum group differ from Eutittha by embolic base in retrolateral position ( Chrysanthus 1967: fig. 11), epigyne with round atrium and large spermathecae, which is twice as long as the atrium ( Rainbow 1920: fig. 74; Chrysanthus 1967: fig. 5).

Eutittha and the two similar genera and the two species of the crucigerum group of Cheiracanthium discussed above are all very different from the punctorium species group of Cheiracanthium , to which the following species can be attributed with confidence: C. punctorium ( Villers, 1789) , C. campestre Lohmander, 1944 , C. effossum Herman, 1879 , C. elegans Thorell, 1875 , C. erraticum ( Walckenaer, 1802) , C. floresense Wunderlich , in Borges and Wunderlich 2008, C. ienisteai Sterghiu, 1985 , C. jorgeense Wunderlich , in Borges and Wunderlich 2008, C. montanum L. Koch, 1877 , C. oncognathum Thorell, 1871 , C. pelasgicum (C. L. Koch 1837) , C. pennatum Simon, 1878 , C. pennyi O. Pickard-Cambridge, 1873 , and C. virescens ( Sundevall, 1833) . This group is quite homogeneous and is characterised by the following combination of characters of the male palp and female epigyne (the list and sequence of characteristics as above): (1) cymbial fold narrow, but slightly protruding on the edge of the cymbium; (2) embolic base in distoprolateral position near conductor; (3) unsclerotized, long, slender and hamiform TA; (4) CD twisted around the spermathecae. Other characteristics typical of punctorium species group are as follows: (5) cymbial spur long, strongly curved ventrally and distinctly thinning at distal section; (6) long embolus forming a complete circle; (7) tibia with PTA and RTA (DTA absent or inconspicuous); (8) epigyne with cavernous depression; (9) spermatheca in one homogenous part; (10) copulatory openings contiguous; (11) spermathecae kidney-, pear-, to elongated sac- or banana-shaped, laterad to the atrium.

Description

Medium-sized; total length 5.3–11.2 in males, 5.1–11.3 in females. Carapace in different shades of yellow or brown with darker pars cephalica; chelicerae the same colour as pars cephalica, brownish yellow, orange or brown; endites and labium yellow, yellowish orange or brown. Thoracic groove is absent. Eyes equal in diameter or anterior eyes larger than posterior ones. Lateral eyes touching or closely spaced. Anterior eyes row slightly recurved; posterior eyes row almost straight or semi procurved. Clypeus low, length about the AME diameter. Chelicerae with two or three pro- and retromarginal teeth. Typical leg formula I-II-IV-III (seldomly I–II, IV–III, I-IV-II–III). Legs yellowish with few spines. Scopula on tarsi and metatarsi. Abdomen oval; in different shades of white or yellow; some species have a middle band dorsally; Forster (1979, p. 92) noted for E. striatica , that ‘in life the abdomen usually has reddish tinge or it may appear yellow’. Anterior spinnerets conical, contiguous; posterior spinnerets longer than anterior ones with slender distal segment.

Palp ( Figure 2 (a–f)). Tibia short (0.5–0.7 times the length of cymbium), with relatively short slightly curved RTA (0.25–0.4 times shorter than tibia). Cymbium elongates oval ( Figure 2 (c)) or drop-shaped ( Figure 2 (a)); cymbial spur short (about 0.2 or 0.4 times the length of cymbium), slightly curved; narrow cymbial fold stretches along the retrolateral margin and it does not break the symmetry of the cymbium ( Figure 2 (c)). Tegulum as truncated circle ( Figure 2 (a)) or truncated oval ( Figure 2 (c)); embolic base in apicalprolateral position behind unsclerotized conductor ( Figure 2 (a,c)); embolus long and thin, encircling tegulum, ending at conductor apex; tegular apophysis absent.

Epigyne ( Figures 1 (b, c) and 2(a, b)). With transverse oval ( Figure 1 (b)) or oblong atrium ( Figure 2 (a)) that is bounded anteriorly by semilunar thin rim (AR; Figure 2 (a)); posterior margin absent. Copulatory openings widely separated from each other, at the bottom of the atrium in lateral position ( Figure 1 (b)). Endogyne with thin-curved copulatory ducts, which is twisted twice or thrice around the spermathecae ( Figures 1 (c) and 2(b)); spermathecae sac- or dumbbell-shaped.

Composition

Nine species: E. insulana Thorell, 1878 , E. brevicalcarata (L. Koch, 1873) , E. excavata ( Rainbow, 1920) , E. lanceolata ( Chrysanthus, 1967) , E. lompobattangi ( Merian, 1911) , E. marplesi ( Chrysanthus, 1967) , E. mordax (L. Koch, 1866) , E. stratiotica (L. Koch, 1873) and E. submordax ( Zhang, Zhu & Hu, 1993) .

Grouping of species in Eutittha is difficult because most of the species are poorly described and illustrated. Nevertheless, according to the scientific status quo meaning the literature available regarding structural features of the palp and epigyne, two species groups can be preliminarily distinguished, namely the insulana -group, comprising E. insulana , E. marplesi and E. lompobattangi , and the mordax -group, comprising E. mordax , E. brevicalcarata , E. stratiotica and E. submordax .

Species of insulana species group are characterised by the following combination of characters of the male palp and female epigyne: (a) cymbium more or less drop-shaped (length/width ratio of cymbium = 1.8–1.9) and tegulum as an apically truncated circle and (b) cymbial spur relatively long (spur length is about 0.4 times the length of cymbium; Figure 2 (a)); (c) PTA clearly visible; (d) epigynal depression transverse ( Figure 1 (b)); (e) spermathecae elongated sac-shaped ( Figures 1 (c) and 2(b)). It seems very likely that E. lanceolata belongs to this group as well.

Species of the mordax species group are characterized by the following combination of characters of the male palp and female epigyne (the list and sequence of characteristics as above): (a) cymbium oval (elongated drop-shaped in other words; length/width ratio of cymbium = 2.1–2.4) and tegulum as an apically truncated oval ( Dondale 1966: fig. 6H) and (b) cymbial spur short (spur length is about 0.2 times the length of cymbium), more or less claw-shaped ( Dondale 1966: figs 6GH; Chen & Huang 2012: fig. 6B); (c) PTA hardly visible ( Dondale 1966: figs 6H); (d) epigynal depression more or less oblong ( Fig. 2a ); (e) spermathecae dumbbell-shaped. It seems very likely that E. excavata belongs to this group as well.

Distribution

South-eastern China, southern Japan, Taiwan, Indonesia, Australia, Polynesia and New Zealand.

Figures

Figure 1. Eutittha insulana Thorell,1878, lectotype female.(a) Dorsal habitus.(b) Epigyne,ventral view. (c) Endogyne, dorsal view. Scale bars: a – 1 mm, b, c – 0.1 mm.

Figure 2. Epigyne and endogyne of Eutittha mordax (L. Koch, 1866) and E. insulana Thorell, 1878. a. E. mordax epigyne, ventral view. b. E. insulana endogyne, dorsal view. Abbreviations: AR – anterior rim; CD – copulatory duct; S – spermathecae. Scale bar: g 0.1 mm.