Acantheis sergeimishenini, Fomichev & Omelko & Marusik, 2023

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 : 119-123

Acantheis sergeimishenini sp. n.

Figs 1–2 , 7–9 , 12–16 , 22–25 , 30 , 46–48

Type. INDONESIA: Sumatra Island: Aceh Prov.: holotype: ♁ ( ISEA, 001.9531), Ketambe Vil. [03°41′N, 97°39′E], 400–500 m, 1988 (precise date unknown), unknown collector .

Etymology. The species name is a patronym given in honor of the teacher and friend of Alexander A. Fomichev, Sergei I. Mishenin (Novosibirsk, Russia), on the occasion of his 60th anniversary. S.I. Mishenin is the first mentor of Alexander A. Fomichev, who inspired his interest in arachnology.

Diagnosis. This new species is similar to A. laetus from Kalimantan and to A. dimidiatus and A. andreimishenini sp. n. from Sumatra in having a slender embolus (Em), a medially located tegular apophysis (TA) and an elongated cymbial tip. The male can be easily distinguished from that of A. laetus by the strongly curved embolus (vs. smoothly rounded, cf. Fig. 23 and Lehtinen 1967: fig. 410). The male of A. sergeimishenini sp. n. differs from that of A. andreimishenini sp. n. in having a larger body size (carapace length 7.7 vs. 5.8), a longer bulb (1.32 mm vs. 1.03 mm), a bifurcated retrolateral tibial apophysis (RTA) (vs. non-bifurcated, cf. Figs 15 and 20 ), the comma-shaped tegular apophysis (in ventral view; vs. round, cf. Figs 23 and 27 ), and the ventral embolic branch (VB) twice as wide as the dorsal one (DB) (vs. the same width, cf. Figs 30 and 31 ). The male of A. sergeimishenini sp. n. differs from that of A. dimidiatus by the bifurcated retrolateral tibial apophysis (vs. non-bifurcated, cf. Figs 15 and 41 ), the comma-shaped tegular apophysis (vs. triangular, cf. Figs 23 and 43 ), and the ventral embolic branch twice as wide as the dorsal one (vs. ventral embolic branch twice as thin as the dorsal one, cf. Figs 30 and 41 ). For a list of the differences between the males of A. sergeimishenini sp. n., A. andreimishenini sp. n. and A. dimidiatus , see Table 7 .

Description. Male. Total length 15.1, carapace 7.7 long, 6.3 wide. Opisthosoma 7.0 long, 4.0 wide. Eye sizes and interdistances: AME 0.46, ALE 0.24, PME 0.5, PLE 0.49, AME–AME 0.2, AME–ALE 0.33, PME–PME 0.21, PME–PLE 0.31, AME–PME 0.21, ALE–PLE 0.2. Clypeus height at AME 0.7, at ALE 1.17. For palp and legs measurements see Table 1 . For palp and legs spination see Table 2. Coloration ( Figs 1–2 , 7–9 ), carapace brown, with a thin longitudinal light stripe. Clypeus, chelicerae, endites and labium dark brown. Sternum and coxae yellow. Palps yellow with brown-grey annulations. Legs yellow-brown, with very vague brown-grey annulations. Opisthosoma yellow-grey with thin longitudinal light stripe dorsally. Posterior part of opisthosoma with two pairs of clusters of stiff yellow setae (CS). Venter of opisthosoma dirty yellow. Spinnerets dark grey.

Male palp as shown in Figs 12–16 , 22–25 , 30 . Tibia ca. 4.5 longer than wide, with 4 very long spines, longest ca. 0.9 of tibia length. Retrolateral tibial apophysis (RTA) small, bifurcated. Ventral RTA branch longer than dorsal one. Cymbium length/width ratio ca. 2.7. Cymbial tip about 0.43 of its length, as long as bulb. Subtegulum (St) large, oval. Tegular length/width ratio ca. 1.5. Sperm duct (SD) clearly visible only in retrolateral view. Retrolateral margin of tegular process (TP) convex. Tegular apophysis (TA) comma-shaped. Conductor (Cn) five times longer than wide, not covering embolic tip. Embolic base with basal process (BP) located near subtegular notch (SN). Membranous extension of embolus (ME) wider than its adjoining part. Embolus (Em) strongly curved, with a small spike (ES) ventrally. Ventral branch of embolus (VB) twice as wide as dorsal one (DB).

Female. Unknown.

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

Figures

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.

FIGURES 7–11. General appearance (7–8), cephalic part (9) and prosoma with legs (10–11) of Acantheis sergeimishenini sp. n. (7–9), and A. andreimishenini sp. n. (10–11). 7—male, dorsal; 8—ditto, ventral; 9—ditto, anterior; 10—ditto, lateral; 11—female, lateral. Scale: 7, 8, 10, 11=1 mm. Abbreviation: CS—cluster of stiff setae.

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 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 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.