Tetragnatha elongata Walckenaer, 1841

Castanheira, Pedro de Souza, Baptista, Renner Luiz Cerqueira, Pizzetti, Daniela Dos Passos & Teixeira, Renato Augusto, 2019, Contributions to the taxonomy of the long-jawed orb-weaving spider genus Tetragnatha (Araneae, Tetragnathidae) in the Neotropical region, with comments on the morphology of the chelicerae, Zoosystematics and Evolution 95 (2), pp. 465-505 : 469-472

Tetragnatha elongata Walckenaer, 1841 Figs 5 , 6 , 7 , 20B , 22B

Tetragnatha elongata Walckenaer 1841: 211 (♂ ♀).

Tetragnatha tropica O. Pickard-Cambridge 1889: 11, pl. 2, fig. 3 (♀); F. O. Pickard-Cambridge 1903: 431, pl. 40, figs 10, 11 (♂ ♀) syn. nov.

Type material.

Tetragnatha elongata : GUADELOUPE: ♂ ♀ syntypes, lost; UNITED STATES OF AMERICA: ♂ neotype, Raleigh, North Carolina (Coll. C. S. Brimley, 21-31.viii.1944, MCZ 21192), not examined. Tetragnatha tropica : GUATEMALA: ♀ holotype, Menché, Godman and Salvin, not located.

Extended diagnosis.

Females of T. elongata can be distinguished from all other Neotropical species by their elongated body, abdomen anteriorly enlarged and much narrower posteriorly, large chelicerae with an outer cusp (OC), and a short genital fold ( Figs 6 A–G , 7B ). The unique internal genitalia has large spermathecae with two thick tubular lobes connected mid-way, forming a kidney-shaped structure, with the median lobe more than twice as long as its width and parallel to each other and to the longitudinal axis of the abdomen ( Fig. 6H ). The lateral lobe is smaller and thinner than the median lobe and may vary in position, with the fundus directed dorsally ( Fig. 6H ) or laterally ( Levi 1981: fig. 76). Central membranous sac (CS) is small and poorly sclerotized ( Fig. 6H ; Levi 1981: fig. 76).

Male chelicerae of T. elongata are similar to those of T. laboriosa Hentz, 1850, insofar as sharing elongated apophyses with excavated tips, elongated and robust ‘T’, and long Gl, the last as the longest teeth of both lower rows ( Figs 5 D–G ; Okuma 1992: fig. 11 A–C). Tetragnatha elongata differs from T. laboriosa by its longer and narrower chelicerae (4.4 × vs 3.5 × longer than wide), ‘sl’ shorter, ‘T’ with larger basis, more elongated and distalward projected, a higher number of ‘rsu’ teeth ( Figs 5D , 7A ; Okuma 1992: 231, fig. 11A), AXl stouter, slender and distalward projected and Gl pointed and much more elongated, both arising from a common base and displaced to a lower position than the remaining lower teeth ( Figs 5 D–F , 7A ; Okuma 1992: 231, fig. 11A, B). Males can also be distinguished from congeners by the palps with conductors having triple pleats, enclosing the long filiform emboli, which bear small bird-head tips that are projected in small tails ( Figs 5 H–J , 7 C–E , 20B ), and by short and thick paracymbia that are perpendicular to the palps axes and with undivided notches, narrow, thin translucent lobes, and thumb-like projecting knobs ( Figs 5K , 7C, F ). The epiandrous field has a large depressed lateral area at both sides of the spigots ( Fig. 7G ).

Synonymy and notes.

Tetragnatha tropica was described from a single female from Guatemala ( Menché, currently Atxchilan, near the Mexican border), not located in NHM or OUMNH collections. Thus, we rely on the original illustrations and subsequent descriptions of both sexes to diagnose this species (O. Pickard-Cambridge 1889: pl. 2, fig. 3; F. O. Pickard-Cambridge 1903: pl. 40, figs 10, 11; Chickering 1957c: figs 97-102). We compared these illustrations with our specimens and the drawings of both sexes and SEM images of the conductor tip of T. elongata by Levi (1981), who proposed a neotype for this species ( MCZ 21192) and identified many specimens from northern Mexico, and with Okuma (1992), who identified specimens from Mexico, Costa Rica, and Panama. Based on our investigations, T. tropica can be diagnosed as a junior synonym of T. elongata because the morphology of male palps and the chelicerae of both sexes perfectly match.

We also highlight that Mello-Leitão (1943, 1945, 1947, 1949) repeatedly recorded T. elongata from Brazil and Argentina, but all his specimens we analysed belong to other common species, especially T. bogotensis and T. nitens . However, after analyzing many other specimens, we were able to confidently record this species for these two countries.

Variation.

Males (n = 8): total length, 7.20-13.45; females (n = 15): total length, 8.88-13.90.

Distribution.

Tetragnatha elongata is a very common species in the Nearctic and Neotropical regions, recorded from Canada ( Dondale et al. 2003) to Misiones, northeastern Argentina ( Fig. 22B ).

Figures

Figure 5. Tetragnatha elongata Walckenaer, 1841, male (MCTP 28045). A. Dorsal habitus; B. Lateral habitus; C. Ventral habitus; D-G. Left chelicera: D. Upper view; E. Inner view; F. Lower view; G. Outer view; H-K. Left male palp: H. Mesal view with tibia; I. Mesal view detail; J. Dorsal view; K. Ventral view (paracymbium). Scale bars: 2 mm (A, B, C); 1 mm (D, E, F, G, H); 0.5 mm (I, J, K).

Figure 6. Tetragnatha elongata Walckenaer, 1841, female. A. Dorsal habitus (MCTP 28045); B. Lateral habitus (MCTP 28045); C-F. Left chelicera (MCTP 28045): C. Upper view; D. Inner view; E. Lower view; F. Outer view; G, H. Genital area: G. Genital fold, ventral view (MCTP 28045); H. Internal genitalia, cleared, ventral view (MCTP 28306). Scale bars: 5 mm (A, B); 1 mm (C, D, E, F); 0.5 mm (G); 0.2 mm (H).

Figure 7. Tetragnatha elongata Walckenaer, 1841, SEM photos. A. Left male chelicera, upper and lower views (MCTP 0229); B. Left female chelicera, upper view (MCTP 43306 ex 0370); C. Left male palp, mesal view (MCTP 0229); D. Left male palp conductor detail and pleats, mesal view (MCTP 0229); E. Tip of conductor detail, dorsal view (MCTP 43306 ex 0370); F. Left male palp paracymbium, ventral view (MCTP 0229); G. Epiandrous field, ventral view (MCTP 43306 ex 0370). Scale bars: 1 mm (A); 0.5 mm (B, C); 0.2 mm (D); 0.01 mm (E); 0.3 mm (F); 0.05 mm (G).

Figure 20. Embolous and conductor tip detail, dorsal view, SEM photos. A. T. bogotensis (MCTP 4299); B. T. elongata (MCTP 43306 ex 0370); C. T. keyserlingi (MCTP 43319 ex 6944); D. T. mandibulata (SMF 1356); E. T. nitens (MACN 2252); F. T. vermiformis (MCTP 43339 ex 1133). Scale bars: 0.05 mm (A, B, C, E, F); 0.02 mm (D).

Figure 22. Records of the material we analysed (circles), including the type localities of Neotropical junior synonyms cited in the text (stars and triangles). A. Tetragnatha bogotensis; B. Tetragnatha elongata; C. Tetragnatha keyserlingi (excluding Haiti); D. Tetragnatha mandibulata; E. Tetragnatha nitens; F. Tetragnatha vermiformis.