Tetragnathidae Menge, 1866

Castanheira, Pedro de Souza, Baptista, Renner Luiz Cerqueira & Oliveira, Francisca Samia Martins, 2022, Five new species of the long-jawed orb-weaving spider genus Tetragnatha (Araneae, Tetragnathidae) in South America, with a key to the species from Argentina and Brazil, Evolutionary Systematics 6 (2), pp. 175-210 : 175

publication ID	https://dx.doi.org/10.3897/evolsyst.6.91418
publication LSID	lsid:zoobank.org:pub:34F513BA-207A-4A4B-9521-20F9F3BE046C
persistent identifier	https://treatment.plazi.org/id/89CA0C96-BC63-5915-A4F8-6AEA5FC0E1B6
treatment provided by	Evolutionary Systematics by Pensoft
scientific name	Tetragnathidae Menge, 1866
status

Treatment

Family Tetragnathidae Menge, 1866 View in CoL

Tetragnatha Latreille, 1804, Tableau Méthodique des Insectes, in Nouveau Dictionnaire d’Histoire Naturelle, 24: 135.

Eugnatha Audouin in Savigny, 1825, Explications sommaires des Planches d’Arachnides de I’Egypte et de la Syrie, p. 119.

Eucta Simon, 1881, Arachnides de France, 5: 5 (Type species by monotypy E. gallica Simon, 1881).

Arundognatha Wiehle, 1963, Tetragnathidae in Tierwelt Deutschlands, 49: 47. (Type species T. striata L. Koch, 1862 designated by Wiehle 1939).

Type-species.

Tetragnatha extensa (Linnaeus, 1758)

Diagnosis.

Tetragnatha differs from Dolichognatha , Pachygnatha and Glenognatha by its elongate and tubular-shaped abdomen, normally covered by guanine crystals. It further differs from Dolichognatha in lacking an epigynum (having a genital fold instead) (Figs 1H View Figure 1 , 15H View Figure 15 ), by having trichobothria on their femora (Fig. 1A-C View Figure 1 , 2A-C View Figure 2 , 6A-C View Figure 6 ), a modified cymbium with its tip elongate and thin and a free paracymbium (e.g., Figs 2I, J View Figure 2 , 6I, J View Figure 6 , 7I, J View Figure 7 ). From Glenognatha and Pachygnatha , it may be identified by the absence of a tapetum on the lateral eyes (see Levi 1981) and by the more horizontal and forward projecting chelicerae (e.g., Figs 10A View Figure 10 , 18A, B View Figure 18 ). From Glenognatha , it differs by the normal position (not advanced) of the tracheal spiracle (Cabra-Garcia and Brescovit 2016). From Pachygnatha , it may be distinguished by the sternum not projecting between the coxae, the carapace not covered with short macrosetae immersed in pits and the absence of the sclerotized genital slit ( Dimitrov and Hormiga 2009; Alvarez-Padilla and Hormiga 2011). Adult Tetragnatha build orb-webs, while adult Pachygnatha do not spin webs. Additionally, Tetragnatha differs from Cyrtognatha by the more elongated abdomen, the absence of the straight line of long and robust macrosetae with enlarged bases on the spinnerets, male pedipalps with paracymbium as a separate sclerite connected to the cymbium by a membrane on its base, and females with enlarged spermathecae (reduced in Cyrtognatha ) (Figs 1B, I View Figure 1 , 2A, B, H, J View Figure 2 ; Dimitrov and Hormiga 2009).

Description.

Carapace longer than wide, normally with an elevated anterior part, without projections or bands (e.g., Figs 1A, B View Figure 1 , 2A, B View Figure 2 , 6A, B View Figure 6 ). Eyes normally large, ringed in black, with touching ALE and PLE in some species (e.g., Fig. 6A, B View Figure 6 ). Fovea normally small and visible (e.g., Figs 1A, B View Figure 1 , 2A, B View Figure 2 ). Sternum oval, longer than wide, sometimes with dusky edges, with or without a dark contour (e.g., Figs 1C View Figure 1 , 2C View Figure 2 , 6C View Figure 6 , 7C View Figure 7 ). Legs varying from pale yellow to light brown, legs I and II normally slightly darker than III and IV, all very long, leg formula I-II-IV-III or I-IV-II-III, leg I always much longer than all others, twice as long as leg III and sometimes having multiple spines on femur (e.g., Figs 1A, B View Figure 1 , 2A, B View Figure 2 , 6A, B View Figure 6 ). Chelicerae elongated, with paturon bearing bulges or crests in some species (Figs 6D, F View Figure 6 , 7D, F View Figure 7 , 14D, F View Figure 14 ) and abundant teeth on both sides, with males bearing a dorsal apophysis to lock female’s fangs and additional or modified teeth, such as ‘sl’, ‘t’ and ‘T’ (Figs 2D-G View Figure 2 , 6D-G View Figure 6 , 7D-G View Figure 7 , 10D-G View Figure 10 , 14D-G View Figure 14 ); fangs may have basal (BC), outer (OC), inner (IC) or median cusps (MC) (e.g., IC and MC in Fig. 1D-F View Figure 1 or BC in Castanheira et al. 2019, fig. 12D-F). Abdomen longer than carapace, normally covered by guanine crystals, without tubercules or spines, sometimes with a projection after the spinnerets varying from short (e.g., Fig. 10B, C View Figure 10 ) to extremely elongated ( Castanheira and Baptista 2021b, figs 1B, C, 2 B, C, 4A, B). Male pedipalps with elongated cymbium, as long (e.g., T. elongata ) or longer than the tibia (e.g., T. vermiformis ) ( Castanheira et al. 2019, figs 5H, 17H-J, 19C). Tibia very short (e.g., T. jaculator ) ( Castanheira and Baptista 2021a, figs 63-65, 78), short (e.g., T. cristata sp. nov., T. oncognatha sp. nov.) (Figs 7H-J View Figure 7 , 8C View Figure 8 , 14H-J View Figure 14 ), or elongated (e.g., T. elongata , T. nitens ) ( Castanheira et al. 2019, figs 5H, 14G-I, 16E). Tegulum oval, always wider than long, slightly (e.g., T. elongata , Castanheira et al. 2019, fig. 5H) or extremely slanted (e.g., T. jaculator , Castanheira and Baptista 2021a, figs 63-65, 78). Conductor always twisted, with pleats varying from three (e.g., T. elongata ) ( Castanheira et al. 2019, figs 5H, I, 7C, D) to zero (e.g., T. cristata sp. nov. (Figs 7H View Figure 7 , 8C View Figure 8 ), and tip of conductor and embolus with or without tail-like projections ( Castanheira et al. 2019, fig. 20A-F). Embolus tip may be completely covered by the pouch-like conductor (e.g., T. bogotensis ) ( Castanheira et al. 2019, figs 1I, J, 3A, E, 20A), partially exposed (e.g., T. argentinensis ; T. cristata sp. nov.) (Figs 7H, I View Figure 7 , 8C, D View Figure 8 ; Cargnelutti et al. 2022, figs 2H, I, 3E, F) or completely apart from the conductor (e.g., T. amazonica sp. nov.; T. tenuissima ) (Fig. 6H, I View Figure 6 ; Castanheira and Baptista 2020, figs 12G, H, 14E, F). Paracymbium may be very elongated (e.g., T. bogotensis ; T. nitens ) ( Castanheira et al. 2019, figs 1K, 3D, 14J, 16F) or reduced in size (e.g., T. amazonica sp. nov.; T. jaculator ) (Fig. 6J View Figure 6 ; Castanheira and Baptista 2021a, figs 65, 80). Paracymbium notch (N) can be carved in two parts (e.g., T. bogotensis , T. nitens ) ( Castanheira et al. 2019, figs 1K, 3D, 14I, J, 16F), slightly dented (e.g., T. cristata sp. nov., T. oncognatha sp. nov.) (Figs 7J View Figure 7 , 8E View Figure 8 , 14J View Figure 14 , 16G View Figure 16 ) or rounded and not divided (e.g., Tetragnatha elongata , T. keyserlingi ) ( Castanheira et al. 2019, figs 5K, 7F, 8J, 10E); Paracymbium translucent lobe (L) can be very broad (e.g., T. nitens , T. chauliodus , T. renatoi ) ( Castanheira et al. 2019, figs 14I, J, 16F; Castanheira and Baptista 2020, figs 4I, 6F, 9K), reduced (e.g., T. keyserlingi ) ( Castanheira et al. 2019, figs 8J, 10E) or not visible (e.g., T. elongata , T. vermiformis ) ( Castanheira et al. 2019, figs 5K, 7F, 17J, 19E). Female genital fold varies from short and wider than long, with straight or curved posterior rim (e.g., T. megalocera , T. renatoi , T. tenuissima ( Castanheira and Baptista 2020, figs 2H, 5H, 13G), to extremely elongated and longer than wide, with rounded posterior rim ( T. cladognatha , T. bogotensis , T. keyserlingi , T. mandibulata , T. nitens , T. pradoi sp. nov.) (Figs 1H View Figure 1 , 18G View Figure 18 ; Castanheira et al. 2019, figs 2G, 9H, 12H, 15J). Female internal genitalia usually with central membranous sac (CS), but it is sometimes absent (e.g., T. vermiformis , T. laboriosa ) ( Castanheira et al. 2019, fig. 18I; Castanheira and Baptista 2021a, fig. 47). CS may have its head varying from rounded or oval (e.g., T. oncognatha sp. nov., T. bogotensis , T. mandibulata , T. nitens ) (Fig. 12I View Figure 12 ; Castanheira et al. 2019, figs 2H, I, 12I, 15K, L) to cylindrical or thin and slender (e.g., T. pradoi sp. nov., T. tenuissima ) (Fig. 15H View Figure 15 ; Castanheira and Baptista 2020, fig. 13H), with variable stalk length, from short (e.g., T. oncognatha sp. nov., T. bogotensis ) (Fig. 15I View Figure 15 ; Castanheira et al. 2019, fig. 2H, I) to very elongated ( T. keyserlingi ) ( Castanheira et al. 2019, fig. 9I), or even having either long or short stalks depending on the specimen ( T. nitens ) ( Castanheira et al. 2019, fig. 15K, L). Spermathecae varies in number, either two (one on each side) (e.g., T. cladognatha , T. elongata , T. mandibulata ) (Figs 1I View Figure 1 , 3I View Figure 3 ; Castanheira et al. 2019, figs 6H, 12I), but sometimes four (e.g., T. megalocera , T. guatemalensis , T. laboriosa ) ( Castanheira and Baptista 2020, fig. 2I; Castanheira and Baptista 2021a, figs 20, 47), and in shape, from perfectly globular ( T. oncognatha sp. nov.) (Fig. 15I View Figure 15 ) to oval (e.g., T. bogotensis , T. mandibulata , T. nitens ) ( Castanheira et al. 2019, figs 2H, I, 12I, 15K, L) or even kidney-like ( T. elongata , T. vermiformis ) ( Castanheira et al. 2019, figs 6H, 18I). Colour of specimens is variable, encompassing reddish, yellowish, brown and orange hues depending on time spent in alcohol (e.g., Figs 1A, B View Figure 1 , 6A View Figure 6 , 11A View Figure 11 ). Old specimens, such as the female T. paraguayensis , usually lose completely their original colour, presenting a light-yellow bleached tone ( Castanheira and Baptista 2021b, fig. 4A).