Dolichognatha sumatrana Fomichev et Omelko, 2025

Fomichev, A. A. & Omelko, M. M., 2025, A NEW SIX-EYED SPECIES OF DOLICHOGNATHA O. PICKARD-CAMBRIDGE, 1869 (ARANEAE: TETRAGNATHIDAE) FROM SOUTHEAST ASIA, Far Eastern Entomologist 517, pp. 1-8 : 3-8

Genus Dolichognatha O. Pickard-Cambridge, 1869

Dolichognatha sumatrana Fomichev et Omelko , sp. n. https://zoobank.org/NomenclaturalActs/ 017694FB-A5A6-4F58-86A3-5F712ADA29E6

Figs 1–19

MATERIAL. Holotype: ♂, Indonesia: Sumatra Island , Aceh Prov., Ketambe Vill., 03°41′N, 97°39′E, 400–500 m, 1988 (precise date unknown), collector unknown ( ISEA, 001.9163). Paratypes: together with the holotype, 1♀ ( ISEA, 001.9164), 1♀ ( ISEA, 001.9165) .

DIAGNOSIS. The new species differs from all congeners, except D. bannaensis Wang, Zhang et Peng, 2020 from China, D. chimminiensis Anju, Asha et Sudhikumar, 2024 from India, D. junlitjri ( Barrion-Dupo et Barrion, 2014) from Philippines and D. longiceps ( Thorell, 1895) from India, Burma and Thailand by total reduction of PME in both sexes. The male of D. sumatrana sp. n. differs from those of D. bannaensis , D. chimminiensis and D. longiceps by strongly elongated chelicerae: chelicera length/carapace height ratio = 3/1 (vs. 2/1–2.5/1). Additionally, the male of new species differs from those of D. bannaensis , D. chimminiensis and D. junlitjri by the presence of 2 promarginal cheliceral teeth (vs. 3) and by square ecto-basal cymbial process (CEBP) in dorsal view (vs. hook-shaped or triangular; cf. Wang et al., 2020: Fig. 13, fig 3H), Anju et al., 2024: fig. 1J and Barrion-Dupo & Barrion, 2014: fig. 1J). The male of D. sumatrana sp. n. can be distinguished from that of D. longiceps by short and straight conductor (C) (vs. long and curved) and by the presence of digitiform apophysis (DA) of CEBP in ventral view (vs. absence; cf. Dimitrov et al., 2010: fig. 11 and 4A). The female of new species differs from those of D. bannaensis and D. junlitjri by crescent-shaped atrium (At) (vs. oval or heartshaped; cf. Wang et al., 2020: Fig. 16 and Barrion-Dupo & Barrion, 2014: fig. 3I and fig. 1D). Additionally, the female of new species differs from the female of D. bannaensis by globular S (vs. arcuate; cf. Wang et al., 2020 L: fig. 18 and fig. 3J). The female of D. sumatrana sp. n. can be distinguished from that of D. longiceps by fertilization ducts (FD) located between the spermathecae (S) (vs. FD located on the sides of S; cf. Dimitrov et al., 2010: fig. 18 and fig. 4E). The female of D. sumatrana sp. n. can be distinguished from that of D. chimminiensis by S consisting of ca. 3 tightly fused chambers (vs. ca. 8 loose chambers; cf. Anju et al., 2024: fig. 18 and fig. 1Q).

DESCRIPTION. Male. Total length 5.65. Carapace: 3.0 long, 1.85 wide. Abdomen: 2.75 long, 1.85 wide. Coloration. Carapace light yellow with wide gray lateral bands. Cephalic part with gray edges. Chelicerae and labium yellow. Endites yellow brown. Sternum yellow with eight gray spots: three paired spots near edges, one spot medially and one more posteriorly. Coxae yellow with gray spots. Palps light yellow, cymbium brown. Legs yellow brown with vague dark annulations. Abdomen yellow gray dorsally and laterally. Venter of abdomen yellow. Dorsum of abdomen with pattern formed by silver dots. Spinnerets yellow gray. Eye sizes and interdistances: AME 0.17, ALE 0.16, PME lost, PLE 0.17, AME–AME 0.14, AME–ALE 0.14, PLE–PLE 0.67, ALE–PLE 0.31. Clypeus height at AME 0.09. Clypeus height at ALE 0.16. Leg measurements: I: 5.2, 1.25, 4.9, 5.0, 1.45 (17.8); II: 3.7, 1.1, 3.15, 3.4, 1.1 (12.45); III: 1.95, 0.65, 1.25, 1.55, 0.7 (6.1); IV: 3.0, 0.75, 2.15, 2.65, 0.9 (9.45). Leg spination: I: Fe d4 p4 r5 v8; Pa d1; Ti d2 p3 r3; Mt d1 p1 r1 v2. II: Fe d4 p4 r4 v5; Pa d1; Ti d2 p2 r2; Mt d1 p1 r1 v2. III: Fe d4 p3 r2 v1; Pa d1; Ti d1 p1 r1 v1; Mt d1 p2 r1 v2. IV: Fe d4 p2 r2; Pa d1; Ti d2 p1 r1 v1; Mt d1 p2 r1. Chelicerae with 2 promarginal teeth and 3 retromarginal teeth.

Male palp as shown in Figs 10–15. Femur 2 times longer than patella. Tibia 1.5 times longer than patella. Cymbium inverted teardrop-shaped, 2.3 times longer than wide. Ecto-basal cymbial process (CEBP) square in dorsal view. Digitiform apophysis (DA) of CEBP as long as paracymbium (P). P equal in size to DA, elongated, covered with long black setae. Tegulum (T) eight-shaped, 2 times wider than long. Subtegulum (St) oval, as wide as long. Anterior edge of T with deep notch (TN). Sperm duct (SD) transversal. Conductor (C) short, elliptical in prolateral view. Embolic apophysis (EA) poorly sclerotized, with blunt apex. Embolus (E) straight, 1.5 times longer that C.

Female. Total length 7.7. Carapace: 3.3 long, 2.1 wide. Abdomen: 5.15 long, 3.3 wide. Coloration. Pars cephalica brown with yellow median spot. Pars thoracica light yellow with wide gray lateral bands. Chelicerae yellow brown. Labium yellow gray. Endites dark brown posteriorly, yellow anteriorly. Sternum yellow with three pairs of dark gray spots near edges and median stripe. Coxae yellow. Palps and legs yellow brown with vague dark annulations. Abdomen (damaged) yellow gray with silver dots. Spinnerets yellow gray. Eye sized and interdistances: AME 0.2, ALE 0.17, PME lost, PLE 0.17, AME–AME 0.14, AME–ALE 0.14, PLE–PLE 0.79, ALE– PLE 0.31. Clypeus height at AME 0.16. Clypeus height at ALE 0.23. Leg measurements: I: 5.2, 1.3, 4.5, 4.25, 1.35 (16.6); II: 3.75, 1.2, 2.95, 3.05, 1.1 (12.05); III: 2.0, 0.75, 1.2, 1.5, 0.7 (6.15); IV: 3.45, 0.85, 2.25, 2.8, 0.9 (10.25). Leg spination: I: Fe d3 p4 r6 v9; Ti d2 p3 r3; Mt d1 p1 r1 v2. II: Fe d4 p4 r4 v5; Pa d1; Ti d1 p2 r2 v1; Mt d1 p1 r1 v2. III: Fe d3 p1 r1 v1; Pa d2; Ti d1 p1 v1; Mt d1 p2 r1 v2. IV: Fe d4 p2 r1; Pa d2; Ti d1 p1 r1 v2; Mt d1 p2 v1. Chelicerae with 2 promarginal teeth and 5 retromarginal teeth.

Epigyne as shown in Figs 16–18. Atrium (At) crescent-shaped, 4 times wider than long. Spermathecae (S) small and globular. Fertilization ducts (FD) parallel to each other, pointed anteriorly.

DISTRIBUTION. Only known from the type locality ( Fig. 19).

ETYMOLOGY. The specific name derived from Sumatra Island, adjective.

Besides Dolichognatha sumatrana sp. n., only four other six-eyed species of the genus are known: D. bannaensis , D. chimminiensis , D. junlitjri and D. longiceps . All these species have been described exclusively from Southeast Asia or India ( Fig. 19). Dolichognatha longiceps was originally described in a separate genus, Prolochus Thorell, 1895 , which was established, among other criteria, based on having only six eyes ( Thorell, 1895). The genus Prolochus was subsequently treated as a junior synonym of Dolichognatha by Levi (1981). Levi justified his decision by noting that in some Dolichognatha species, the posterior median eyes are reduced in size. Barrion-Dupo and Barrion opposed this decision, describing D. junlitjri from the Philippine Islands as part of Prolochus ( Barrion-Dupo & Barrion, 2014) . They emphasized that the total loss or reduced size of posterior median eyes are distinctive separable features useful for distinguishing taxa at the generic level. Kallal and Hormiga concluded this discussion by reaffirming the synonymy of Prolochus with Dolichognatha in their molecular phylogenetic analysis of metaine Tetragnathidae ( Kallal & Hormiga, 2018) .

The work of Mikhail M. Omelko was carried out within the state assignment of Ministry of Science and Higher Education of the Russian Federation (theme No. 124012400285-7). We are grateful to Yuri M. Marusik (Magadan, Russia) for reviewing the draft version of manuscript.