Tetragnatha oncognatha, Castanheira & Baptista & Oliveira, 2022

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

Tetragnatha oncognatha sp. nov.

Figs 14 , 15 , 16 , 17

Type-material.

Holotype male, Rancho Queimado (27°40'22.0"S, 49°01'19.0"W, Santa Catarina, Brazil), 09-13.x.1995, AA Lise leg. (MCTP 7067). Paratypes: Brazil, Rio de Janeiro • 1 male, 1 juvenile, Itatiaia, Parque Nacional de Itatiaia, 22°29'29.0"S, 44°33'33.0"W, 20-22.xi.2008, DT Castro leg. (UFRJ 0423); Rio Grande do Sul • 1 male, Guaíba, Fazenda São Maximiliano, 30°06'50.0"S, 51°19'30.0"W, 14.vii.1995, AA Lise leg. (MCTP 6688); • 1 male, 1 female, São Francisco de Paula, 29°26'52.0"S, 50°35'02.0"W, 05-09.iii.1997, AA Lise leg. (MCTP 15965).

Additional material examined.

Brazil - Rio Grande do Sul • 1 female , Novos Cabrais , 29°44'06.0"S, 52°56'52.0"W, 27.i.2010, RG Buss leg. (MCTP 43654); • 1 male , São Francisco de Paula, Potreiro Velho , 29°24'47.9"S, 50°15'36.8"W, 12-14.xi.1998, AA Lise leg. (MCTP 12037); • 1 male , same locality, 04-06.i.1999, AA Lise leg. (MCTP 15792); • 2 males, 2 females , same locality, 14-17.xii.1996, AA Lise leg. (MCTP 43336); • 1 male , Santo Antonio da Patrulha , 29°49'04.0"S, 50°31'12.0"W, 27.viii.1994 (MCTP 4929); • 1 male , Viamão, 30°04'51.0"S, 51°01'22.0"W, 07.xi.1995, AA Lise et. al. leg. (MCTP 43337); • 1 male , Viamão, Itapuã,, 30°17'02.7"S, 51°01'23.3"W, 29.v.2004, BP Zambonato leg. (MCTP 33638) ; Santa Catarina • 1 male , Florianópolis: Morro das Aranhas, Costao do Santinho , 27°28'05.9"S, 48°22'49.8"W, 2007, F Albertoni leg. (IBSP 144176) ; São Paulo • 1 female , São Paulo, Parque Ilha dos Eucaliptos, Jardim Ângela, Reservatorio de Guarapiranga , 23°44'00.0"S, 46°44'01.5"W, 07-13.x.2003, I Cizauskas and CRM Garcia leg. (IBSP 61361) .

Diagnosis.

Males of T. oncognatha sp. nov. share with T. cristata sp. nov. and T. jaculator similar small-sized cylindrical bodies and small chelicerae, with ‘a’ small sized and ‘T’ long distalward projected (Figs 7A-E, G , 8A , 14A-E, G , 16A ; Castanheira and Baptista 2021a, figs 56, 57, 59, 60, 62, 74). However, T. oncognatha sp. nov. is easily identified by chelicerae with small AXu, much more conspicuous and rounded cheliceral bulge, and deep lower crest beginning before Gl and ending after L2, embolus opening inside ventral portion of conductor and paracymbium with narrower lobe and longer notch (Figs 14D-F, H-J , 16A, B, E-G ). Females are similar to T. guatemalensis in regard to chelicerae and genitalia, but T. oncognatha sp. nov. is distinguished by chelicerae with much smaller U2 and L2, much larger gaps between Gl and L2 and between L2 and L3, no outer cusp, more rounded genital fold and internal genitalia formed by much larger central sac and two much more rounded spermathecae (Figs 15D-I , 16C, D ).

Description.

Male (holotype, MCTP 7067): Carapace elongated and, tapering toward slightly elevated anterior part, with rounded borders and yellowish brown colour hue with thin dark line rebordering its edges (Fig. 14A, B ). Labium subquadrate and dark brown (Fig. 14C ). Sternum oval and light brown, with no marks or contour (Fig. 14C ). ALE and PLE touching each other (Fig. 14A ). Legs yellowish brown with four pairs of spines on femur (Fig. 14A-C ). Chelicerae paturon approximately 3.3 × longer than wide and 1.6 × shorter than carapace, moderately curved outwards, around 30° from body median line, moderately thick and with orange-brown colour hue, bearing a large and rounded conspicuous bulge (CB) between teeth rows (Figs 14A, D-G , 16A, B ). ‘a’ short, thick, out- and distalward projected, continuously bent from its basis, except in its last third, which bears a more abrupt curvature; with a carved tip, and located in middle portion of paturon (Figs 14D, E , 16A ). AXu very reduced, almost a nub, located on fang furrow (Figs 14D, E , 16A ). Upper row with six uneven teeth distalward projected (Figs 14D, E , 16A ): Gu small, thick, pointed, slanted and displaced from fang furrow and row itself, apart from ‘T’ by a large gap formed by CB; ‘sl’ absent; ‘T’ elongated, thick, and very pointed, with very large basis; ‘rsu’ with four almost straight pointed teeth decreasing in size. AXl absent (Figs 14E, F , 16B ). Lower row with seven teeth distalward projected (Figs 14E, F , 16B ): Gl elongated, thick, finger-like and located on edge of fang furrow, alongside L2 on soft lower crest (CRl); L2 and L3 pointed, L2 more sclerotized and apart from L3 by a conspicuous gap, partially covered by CRl and L3 apart from L4 by a gap of same size; L4-L7 very pointed, L4 with almost same size as L6, L5-L7 decreasing in size, with L7 very reduced. Cheliceral fang moderately thick, and closing between teeth rows (Figs 14D-F , 16A, B ). Abdomen medium-sized, around 1.9 × longer than carapace, cylindrical and beige, dorsally covered by guanine crystals, bearing a lateral dark line (Fig. 14A-C ). Epiandrous field oval and flat, with wide distal part, bearing six and eight spigots in two bands apart by a large midway division (Fig. 16H ). Pedipalps with elongated cymbium, around 2 × longer than short, distally bending laterad, with rounded tibia (Figs 14H, I , 16E ); tegulum around 1.3 × wider than long, spherical and inflated (Figs 14H, I , 16E ); conductor twisted, only medially thicker and sclerotized, with wide tip completely enfolding embolus as a wide and projected pouch, which projects beyond embolus tip as a cap (Figs 14H, I , 16E, F ); embolus short, thick and sinuous, originating at the middle portion of the bulb, near the cymbium (Figs 14H, I , 16E, F ); paracymbium around 3.4 × longer than wide, triangular, thick and moderately downward slanted at its tip, with a finger-like notch, translucent lobe occupying around 40% of the paracymbium length, neither reaching its basis, nor its apex, knob large and not projected (Figs 14J , 16G ).

Measurements. Total length 6.1. Carapace 2.0 long, 1.3 wide. Abdomen 4.2 long, 1.1 wide. Left chelicera 1.2 long, 0.4 wide. Leg formula I-II-IV-III. Leg I: femur 2.9, patella 0.8, tibia 4.9, metatarsus 4.1 and tarsus 0.7. Leg II: patella + tibia 3.8. Leg III: patella + tibia 1.6. Leg IV: patella + tibia 2.4.

Female (paratype MCTP 15965): Carapace colour, maxillae, fovea, eyes, labium, and legs similar to male, but sternum dusky, with light brown spots between coxae (Fig. 15A-C ). Chelicera paturon around 2.6 × longer than wide, 1.9 × shorter than carapace and bending around 25° from body median line, with similar colour hue as male (Figs 15A, D-G , 16C, D ). AXu absent (Figs 15D, E , 16C ). Upper row with seven teeth distalward projected (Figs 15D, E , 16C ): Gu large, thick, pointed, very sclerotized and triangular, located on fang groove and apart from U2 by medium-sized gap; U2 small, with size similar to U7, triangular and pointed, apart from U3 by medium-sized gap; U3-U7 decreasing in size and pointed. AXl absent (Figs 15E, F , 16D ). Lower row with six teeth distalward projected (Figs 15E, F , 16D ): Gl triangular, thick and very sclerotized, located on fang groove and apart from L2 by medium-sized gap; L2 small, triangular and pointed, apart from L3 by medium-sized gap; L3-L6 decreasing in size and pointed. Cheliceral fang thick, uniformly tapering, serrated and abruptly curving from midway to its tip (Figs 15D-F , 16C, D ). Abdomen slightly longer than that of male, around 2.6 × longer than carapace, and bearing wider lateral black line (Fig. 15A-C ). Genital fold short, around 4.7 × wider than long, with a straight posterior rim and with beige colour hue (Fig. 15H ). Internal genitalia with two massive globular spermathecae connected to a rounded uterus externus, and a large and oval central membranous sac, with very short stalk (Fig. 15I ).

Measurements. Total length 8.5. Carapace 2.5 long, 1.4 wide. Abdomen 6.0 long, 1.4 wide. Left chelicera 1.1 long, 0.5 wide. Leg formula I-II-IV-III. Leg I: femur 4.4, patella 0.8, tibia 5.1, metatarsus 5.4 and tarsus 1.3. Leg II: patella + tibia 3.5. Leg III: patella + tibia 1.6. Leg IV: patella + tibia 3.1.

Etymology.

The specific Greek epithet " Tetragnatha oncognatha " refers to the gibbous, inflated chelicerae of both sexes, and is composed of the latinized form of the Greek " onkos " meaning "tumour, swell", and " gnatha " meaning "mouthpart, chelicera".

Variation.

Males (n = 6): total length, 4.2 - 6.2. Male L3 may be absent, increasing the length of the gap (Fig. 14E, F vs. Fig. 16B ). No conspicuous colour variations between specimens was detected.

Distribution.

The distribution of this species ranges from Itatiaia in South-centre Rio de Janeiro state, through Rancho Queimado in Centre-east Santa Catarina state, to Guaíba in South-centre and Viamão in Northeast Rio Grande do Sul state, all in Brazil (Fig. 17 ).

Life history and habitat preferences.

Mature males and females of T. oncognatha sp. nov. were collected in January, March, May, July, August, and October to December, therefore the species does not seem to have a specific maturity period. No information on habitat preferences was provided on the original labels.

Figures

Figure 7. Tetragnatha cristata sp. nov. male holotype (MCTP 43332). 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-J. Left pedipalp; H. Mesal view; I. Dorsal view; J. Ventral view (paracymbium). Scale bars: 2 mm (A-C); 0.2 mm (D-J).

Figure 8. Tetragnatha cristata sp. nov. male SEM photos. A, B. Left chelicera (MCTP 21570); A. Upper view; B. Lower view; C-E. Left male pedipalp (MCTP 43334); C. Mesal view; D. Tip of conductor and embolus opening detail, dorsal view; E. Paracymbium detail, ventral view; G. Epiandrous field detail, ventral view (MCTP 43334). Scale bars: 0.2 mm (A, B); 0.1 mm (C.); 0.05 mm (D, E); 0.02 mm (F).

Figure 14. Tetragnatha oncognatha sp. nov. male holotype (MCTP 7067). 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-J. Left pedipalp; H. Mesal view; I. Dorsal view; J. Ventral view (paracymbium). Scale bars: 2 mm (A-C); 0.2 mm (D-J).

Figure 15. Tetragnatha oncognatha sp. nov. female paratype (MCTP 15965). 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-I. Female genitalia; H. Genital fold, ventral view; I. Internal genitalia, dorsal view. Scale bars: 2 mm (A-C); 0.2 mm (D-I).

Figure 16. Tetragnatha oncognatha sp. nov. SEM photos. A, B. Male left chelicera; A. Upper view (MCTP 15965); B. Lower view (MCTP 15792); C, D. Female left chelicera (MCTP 43654); C. Upper view; D. Lower view; E-G. Left male pedipalp; E. Mesal view (MCTP 4929); F. Tip of conductor and embolus opening detail, ventral view (MCTP 15792); G. Paracymbium detail, ventral view (MCTP 15792); H. Epiandrous field detail, ventral view (MCTP 15965). Scale bars: 0.2 mm (A-D); 0.1 mm (E); 0.05 mm (F, G); 0.02 mm (H).

Figure 17. Distribution of T. oncognatha sp. nov.