Acantheis dimidiatus ( Thorell, 1890 )

Fomichev, Alexander A., Omelko, Mikhail M. & Marusik, Yuri M., 2023, A survey of the Sumatran Ctenidae (Araneae). 1. Two new Acantheis species, Zootaxa 5353 (2), pp. 117-130 : 128

Acantheis dimidiatus ( Thorell, 1890)

Figs 36–48

Acanthoctenus dimidiatus Thorell, 1890: 134 (♁).

Acantheis dimidiatus — Simon 1897: 117.

Material examined. 1♁ (holotype) ( MSNG), INDONESIA: Sumatra Island: Singalong, O. Beccari. Examined by photo .

Diagnosis. The species is similar to A. laetus from Kalimantan and to A. sergeimishenini sp. n. and A. andreimishenini sp. n. from Sumatra in having the slender embolus (Em), the medially located tegular apophysis (TA) and the elongated cymbial tip. The male of A. dimidiatus differs from that of A. laetus by by the strongly curved embolus (vs. smoothly rounded, cf. Fig 43 and Lehtinen 1967: fig. 410).The male of A. dimidiatus can be distinguished from that of A. sergeimishenini sp. n. by the non-bifurcated retrolateral tibial apophsis (RTA) (vs. bifurcated, cf. Figs 41 and 15 ), the triangular tegular apophysis (vs. comma-shaped, cf. Figs 43 and 23 ), and the ventral embolic branch twice thinner than dorsal one (vs. ventral embolic branch twice wider than dorsal one, cf. Figs 41 and 30 ). From the males of A. andreimishenini sp. n. those of A. dimidiatus differs by the dorsal surface of opisthosoma with a thin stripe reaching spinnerets (vs. wide cardiac mark reaching middle part of opisthosoma, cf. Figs 36 and 3 ), the median band on the carapace as wide as distance between PME (vs. as wide as the distance between PLE), the triangular tegular apophysis (TA) (vs. circular, cf. Figs 43 and 27 ), and the ventral embolic branch twice thinner than dorsal one (vs. dorsal and ventral embolic branches equal in size, cf. Figs 41 and 31 ). For a complete list of the differences between the males of A. dimidiatus , A. sergeimishenini sp. n. and A. andreimeshenini sp. n. see Table 7 .

Description. Male palp as shown in Figs 37–43 . Tibia ca. 4.6 longer than wide, 4 very long spines, longest ca. 0.7 of tibia length. Retrolateral tibial apophysis small, non-bifurcated. Cymbial tip about 0.42 of its length, slightly shorter than bulb. Sperm duct clearly visible only in retrolateral view. Tegular apophysis triangular. Embolus strongly curved. Ventral branch of embolus twice thinner than dorsal one.

Female. Unknown.

Distribution. Only known from the type locality ( Figs 46–48 ).

Figures

FIGURES 36–44. Habitus (36), whole palp (37–38), terminal part of the palp (39–42), bulb (43) and labels (44–45) of the holotype of Acantheis dimidiatus Thorell, 1890. 36, 42—dorsal; 37, 39—prolateral; 38, 41—retrolateral; 40, 43—ventral.

FIGURES 46–48. Collecting localities of A. sergeimishenini sp. n. (circle), A. andreimishenini sp. n. (square), and A. dimidiatus Thorell, 1890 (triangle). The frame on Fig. 48 refers to the content of Fig. 47 and the frame on Fig. 47 refers to the content of Fig. 46.

FIGURES 12–21. Male palp of Acantheis sergeimishenini sp. n. (12–16), and A. andreimishenini sp. n. (17–21). 12, 17—whole palp, retrolateral; 13, 18—terminal part of the palp, prolateral; 14, 19—ditto, ventral; 15, 20—ditto, retrolateral; 16, 21—ditto, dorsal. Scale: 12, 17=1 mm; 13–16, 18–21=0.5 mm. Abbreviations: RTA—retrolateral tibial apophysis.

FIGURES 22–29. Bulb of Acantheis sergeimishenini sp. n. (22–25), and A. andreimishenini sp. n. (26–29). 22, 26—prolateral; 23, 27—ventral; 24, 28—retrolateral; 25, 29—apical. Scale: 0.2 mm. Abbreviations: BP—basal process of embolus, Cn— conductor, DB—dorsal branch of embolus, EB—embolic base, Em—embolus, ES—embolic spike, ME—membranous extension of embolus, SD—sperm duct, SN—subtegular notch, St—subtegulum, TA—tegular apophysis, Te—tegulum, TP—tegular process, VB—ventral branch of embolus.

FIGURES 30–35. Terminal part of the embolus (30–31) and female genitalia (32–35) of Acantheis sergeimeshenini sp. n. (30), and A. andreimishenini sp. n. (31–35). 30, 31—retrolateral; 32—intact epigyne, ventral; 33—macerated epigyne, ventral; 34—endogyne, dorsal; 35—epigyne, posterior. Scale: 0.2 mm. Abbreviations: Cn—conductor, DB—dorsal branch of embolus, Em—embolus, ET—epigynal tooth, Fo—fovea, ME—membranous extension of embolus, RI—receptacle’s chamber I, RII—receptacle’s chamber II, Re—receptacle, SB—septal base, SH—septal hump, SS—septal stem, VB—ventral branch of embolus.

FIGURES 1–6. Habitus of Acantheis sergeimishenini sp. n. (1–2), and A. andreimishenini sp. n. (3–6). 1, 3—male, dorsal; 2, 4—male, ventral; 5—female, dorsal; 6—female, ventral. Scale: 2 mm.