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

publication ID

http://dx.doi.org/10.3897/zse.95.36762

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lsid:zoobank.org:pub:61A44D72-5E9B-40C6-9440-27E395110DE8

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scientific name

Tetragnatha elongata Walckenaer, 1841
status

 

Tetragnatha elongata Walckenaer, 1841  Figs 5View Figure 5, 6View Figure 6, 7View Figure 7, 20BView Figure 20, 22BView Figure 22

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–GView Figure 6, 7BView Figure 7). 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. 6HView Figure 6). The lateral lobe is smaller and thinner than the median lobe and may vary in position, with the fundus directed dorsally ( Fig. 6HView Figure 6) or laterally ( Levi 1981: fig. 76). Central membranous sac (CS) is small and poorly sclerotized ( Fig. 6HView Figure 6; 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–GView Figure 5; 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 5DView Figure 5, 7AView Figure 7; 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–FView Figure 5, 7AView Figure 7; 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–JView Figure 5, 7 C–EView Figure 7, 20BView Figure 20), 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 5KView Figure 5, 7C, FView Figure 7). The epiandrous field has a large depressed lateral area at both sides of the spigots ( Fig. 7GView Figure 7).

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. 22BView Figure 22).