Tetragnatha chauliodus ( Thorell, 1890 )

Castanheira, Pedro De Souza & Baptista, Renner Luiz Cerqueira, 2020, Notes on slender species of the long-jawed spider genus Tetragnatha (Araneae Tetragnathidae) with description of three new species, Zootaxa 4768 (1), pp. 43-75 : 59-65

Tetragnatha chauliodus ( Thorell, 1890)

( Figs 9–11 ; Map 2)

Limoxera chauliodus Thorell, 1890: 292 (♂, ♀).

Tetragnatha chauliodus: Gravely, 1921: 425 .

T. chauliodus: Okuma, 1987: 62 , fig. 15A–E (♀)

T. chauliodus: Okuma, 1988b: 196 , fig. 11A–L (♂, ♀, misidentified, = T. chiyokoae new species)

T. chauliodus: Tanikawa, 1990: 9 , figs. 1–9 (♂, ♀, misidentified, = T. chiyokoae new species)

T. chauliodus: Okuma et al., 1993: 44 , fig. 40A–G (♂, ♀, misidentified, = T. chiyokoae new species)

T. chauliodus: Song et al., 1999: 221 , figs. 126A, G, W, X, 127A, B (♂, ♀, misidentified, = T. chiyokoae new species) T. chauliodus: Zhu et al., 2003: 128 , figs. 59A–G, 60A–G (♀, but ♂ misidentified, = T. chiyokoae new species)

Tetragnatha zhangfu Zhu et al., 2003: 197 , fig. 107A–H (♂) new synonymy

T. chauliodus: Tanikawa, 2007: 108 , figs. 401, 402, 865–867 (misidentified, = T. chiyokoae new species)

T. chauliodus: Tanikawa, 2009: 416 , figs. 107–109 (misidentified, = T. chiyokoae new species)

T. chauliodus: Basu & Raychaudhuri, 2016: 219 , fig. 6–10, 40–44 (♀, misidentified, = T. bogotensis Keyserling, 1865 )

Type material. Tetragnatha chauliodus : SINGAPORE: ♂ lectotype and ♀ paralectotype herein designated (Coll. Cel. Workman) ( NHRS: GULI000070711 ), examined (photos) ; MALAYSIA: ♀ paralectotype, Penang [Pinang] (Coll. Cel. Workman), not examined. Tetragnatha zhangfu : CHINA: ♂ holotype, 1♂ and 2 immatures paratypes, Menglun [or Menglong] county (21°054’N, 101°12’E), Yunnan Province (Coll. Zhang Chao, 24.VI.2001), examined (photos) .

Material examined. BRAZIL, Rio de Janeiro: Cachoeiras de Macacu: Reserva Ecológica de Guapiaçu, 08.VIII.2016, R. Baptista leg., 1 ♂, 1 ♀, 2 juveniles [ MNRJ 7518 (lost), UFRJ 1313, UFRJ 1566].

Diagnosis. Male chelicerae of T. chauliodus are similar to those of T. keyserlingi , as both species lack ‘sl’ and share the same position and similar shape of ‘t’, Gu and ‘rsu’ ( Fig. 9D, E ; Castanheira et al. 2019, figs 8D, E, 10A). However, T. chauliodus has smaller chelicerae, with more pronounced ‘t’, more elongated and basalward projected Gu, longer and straighter ‘T’, much longer ‘Gl’ and only five additional teeth in ventral row ( Fig. 9 D–F). Palps of T. chauliodus are similar to T. chiyokoae new species, sharing thin transparent conductor covering the very sclerotized embolus as a thin pouch with large terminal cap, paracymbium with undivided notch, with very wide translucent lobe and large knob ( Figs 7 E–G, 9H–J). T. chauliodus can be distinguished by small tibia, wider terminal cap of the conductor, embolus without straight tip, bearing a terminal curvature and paracymbium with straight distally projected notch, translucent lobe lighter and far from reaching up the notch and knob in a more basal position ( Fig. 8 H–J).

Female chelicerae of T. chauliodus are more alike to those of T. chiyokoae new species and T. tenuissima sharing similar elongated upper crests (CRu) and Gu similar in shape and size ( Figs 8A , 10D, E , 13C, D , 14C ; Okuma 1988b, fig. 40B; Tanikawa 1990, fig. 4). T. chauliodus and T. chiyokoae new species are set apart by chelicerae having only Gu on CRu and apart from U2 by large gap, larger Gl, longer L2, and by the fang bearing a basal cusp (BC), besides having longer genital fold ( Fig. 8A, B , 10 E–G; Okuma 1988b, fig. 40B, F; Tanikawa 1990, figs 3–5). Finally, T. chauliodus differs from T. chiyokoae new species by the presence of an extremely elongated median cusp (MC), which is very reduced or absent in the new species ( Fig. 10 E–G).

Description. Male: Carapace yellow, elongated, much narrower anteriorly and with two darker thin parallel lines from the cephalic furrow, passing through the fovea, reaching the posterior rim ( Fig. 9A ). Labium brown and very elongated ( Fig. 9C ). Sternum light yellow contoured in brown ( Fig. 9C ). Posterior eyes evenly separate with almost same diameter, AME centrally placed, with moderate gap apart from PME, ALE and PME almost touching. Legs yellow and very elongated ( Fig. 9 A–C). Paturon more than 3x longer than wide and little over 60% as long as the carapace, moderately curved outwards, around 45° from the median line of the body ( Fig. 9A, D, F ), thick, and well carved near the apex, after the insertion of the excavated ‘a’, which is protruding, moderately thick, projected distal- and a little outward, and clearly bent from the middle to the apex ( Fig. 9 D–G). ‘t’ small, blunt, upward projected, and located close to ‘a’ ( Fig. 9D, E ). AXu absent ( Fig. 9D, E ). Upper row with five uneven teeth ( Fig. 9D, E ): Gu large, bent basal- and slightly downward, 40% shorter than ‘T’ and apart from it by a significant gap; ‘sl’ absent; ‘T’ thorn-like, long, thin, and almost straight, a little bent downward and ‘rsu’ with three teeth decreasing in size. AXl extremely reduced ( Fig. 9E, F ). Lower row with six teeth ( Fig. 9E, F ): Gl long, thin and slightly pointed distalward, adjoined to the basis of the fang alongside L2, both on a soft crest and apart by a small gap; L2–L5 slightly pointing upward, L2 bulkier than L3–L5 which have approximately the same size and L6 much smaller than the others. Cheliceral fang as wide as its base, bent inward and thinner from its proximal end ( Fig. 9 D–F). Abdomen cylindrical, slender, around 2.4x longer than the carapace, with six grey patches on each side of its dorsum (the first two lighter) ( Fig. 9 A–C). Palps with a very elongated cymbium, bearing thin basis, a slight constriction at the middle, and the distal third thin and slightly curved prolaterally, ending in a roundish point ( Fig. 9 H–J); cymbial tarsal organ vey wide, strongly developed ( Fig. 9H ); tegulum spherical and inflated, more than two times wider than high ( Fig. 9H ); conductor twisted near mid-way, with thin edges enfolding over the embolus as a thin pouch on its median portion and projected as a small transparent cap near the apex ( Fig. 9H, I ); embolus thick, originating at the middle portion of the bulb, near the cymbium, with a long leveled curve at the initial portion, followed by a strong upward curve, then a long almost straight median portion and a ‘S’-shaped terminal portion up to the apex, which is hidden by the conductor ( Fig. 9H, I ); paracymbium wide and elongated, not slanted, tapering toward a finger-like projected notch; translucid lobe wide and long, occupying almost all the ventral side and extending medially for most of the width of the paracymbium; ectal side contoured by a darker line medially and with a large knob, wider than long, with a round tip ( Fig. 9J ).

Total length 5.93. Carapace 1.74 long, 0.83 wide. Abdomen 4.19 long, 0.60 wide. Left chelicera 1.11 long, 0.34 wide. Leg formula I–IV–II–III. Leg I: femur 5.71, patella 0.64, tibia 5.84, metatarsus 5.94 and tarsus 1.50. Leg II: patella + tibia 3.72. Leg III: patella + tibia 1.40. Leg IV: patella + tibia 3.97.

Female: Carapace color, endites, fovea, eyes, labium and legs as in male ( Fig. 10 A–C). Paturon yellow, around 2,7x longer than wide, less than half as long the carapace and gently curved outwards, around 30° from median line of the body, slightly carved near the apex on its upper and outer sides, bearing well projected and distalward teeth on both rows, with CRu facing near the basis of Gu ( Fig. 10 D–G). AXu and AXl absent. Upper row with seven teeth ( Fig. 10D, E ): Gu next to the base of fang and on the distal end of CRu, placed on the top of a deep furrow, apart from U2 by a very large gap, U2–U7 decreasing in size, except by U4 which is smaller and thinner than the others, sharing the same basis with U3. Lower row with eleven teeth ( Fig. 10E, F ): Gl thicker, less pointed and clearly projected downward than other teeth, apart from L2 by a small gap, L3–L5 decreasing in size, L6–L8 also decreasing in size but longer than L5, L9 smaller than all teeth and followed by L10 and L11 with about the same size of L5. Cheliceral fang straight and wide at the basis, abruptly tapering and basalward slanting from its mid-way on, closing between both rows and bearing a small pyramidal basal cusp (BC) and am elongated thumb-like median cusp (MC) at the final of the basal fourth, projected both basal- and downward ( Fig. 10 D–G). Abdomen with same shape as in male but nude, around 3x longer than the carapace ( Fig. 10 A–C), dorsally pale beige, covered by guanine spots, scantier at the middle line, with a pale patch on folium ( Fig. 10A, B ). Venter pale brown, flattened and nude, with neither drawings nor patches ( Figs. 10C ). Genital fold approximately 1.6x wider than long, large, elongated and laterally compressed in half of its length, with a blunt and straight tip ( Fig. 10H ). As this female is one of a kind, the vulva was not dissected, but it can be easily observed in Zhu et al. (2003, fig. 59G) and bears two small rounded spermathecae connected to a large subquadrate uterus externus and a slender cylindrical centrally placed central membranous sac.

Total length 8.21. Carapace 2.09 long, 0.87 wide. Abdomen 6.11 long, 0.64 wide. Left chelicera 0.97 long, 0.36 wide. Leg formula I–IV–II–III. Leg I: femur 5.15, patella 0.77, tibia 5.87, metatarsus 5.92 and tarsus 1.53. Leg II: patella + tibia 3.87. Leg III: patella + tibia 1.50. Leg IV: patella + tibia 4.08.

Synonymic notes and variation. In the original description of Tetragnatha chauliodus, Thorell (1890: 292) cited many somatic characters, but included no illustrations. He based the species on a couple from Singapore and an additional female from Malaysia. He clearly cited the presence of a long MC in the fang of the females he exam- ined ( Thorell, 1890: 295). Afterwards, many authors redescribed T. chauliodus , based on specimens from different countries, with comprehensive illustrations of chelicerae and genitalia of both sexes (e.g. Okuma, 1987, 1988b; Okuma et al., 1993; Tanikawa, 1990; Song et al., 1999; Zhu et al., 2003). However, there are at least two different species identified and illustrated as T. chauliodus , sometimes with males and females not well-matched.

The male and female syntypes of T. chauliodus from Singapore ( Fig. 11 A–C) belong to just one species. We herein formally designate the male from Singapore as lectotype. Both the female from Singapore (examined through photos) and the one from Malaysia (not examined) are then regarded as paralectotypes. Our choice is based on the order of description and measurements on Thorell (1890). Typical males of T. chauliodus , characterized, for example, by Gu very pointed, curved basalward, large ‘t’ and thin and pointed Gl, have been associated with females bearing long MC and robust, straight Gl, as in the Singapore syntypes or our Brazilian specimens ( Figs. 9 D–F, 10C).

In his paper on spiders from India, Gravely (1921) cited T. chauliodus in a section on previously described oriental species of Tetragnatha that could possibly occur in that country. He gave a brief redescription of it, directly based on Thorell’s original description, without any mention to Indian specimens. Okuma (1987, fig. 15) was the first author to illustrate true females of T. chauliodus , adding Papua New Guinea to the species distribution. Following Roewer (1942), she also cited T. chauliodus for Burma [currently Myanmar]. Other doubtful record was given by Okuma (1988b) for Thailand. As all three authors have failed to cite any specimens or previous citations for those countries and we have not also been able to found any actual specimen from them, we do not include India, Myanmar or Thailand in the species distribution, in contrast to the World Spider Catalog (2020).

Okuma (1988b) also misidentified part of the specimens she used on her redescription of T. chauliodus , illustrating typical male and female of T. chiyokoae new species from Taiwan as this species. She associated those males with females from several countries from Australasia, differing in the presence and size of the median cusp, considering this character as variable within the species. She mentioned that females from Southern countries, as Singapore and Papua New Guinea, had long MC, Philippine specimens had intermediate MC, while specimens from Northern countries, as Taiwan, had small or absent MC. We have not been able to examine female specimens cited by Okuma, but we do not believe that all her females belong to one and the same species, as we pointed above in the diagnosis and notes section of T. chiyokoae new species.

Our studies reveal that females from China, Taiwan and Japan have usually been collected associated with typical T. chiyokoae new species males (e.g, Okuma, 1988b, fig. 40A–G, Tanikawa 1990, figs 1–9). On the other hand, female specimens from southern countries, as the Singapore paralectotype or our specimen from Brazil, were found at the same localities as typical T. chauliodus males.

Actual females of T. chauliodus have paturon shorter and bulkier, Gu not quite sclerotized, with large basis connected to the CRu, Gl medium-sized, transversally placed pointing midway from the inner side, L2 longer and thin, fangs almost straight from the middle third on, without concavity or keel at its inner margin, with long and clearly visible MC ( Fig. 10 D–G), contrasting to the same structures in T. chiyokoae new species ( Fig. 8A, B ). We have not examined any intermediate specimen between the two kinds of females, but we cannot rule out that there may be variation on the cited characters, as in the Philippine specimen cited by Okuma (1988b). However, only a thorough examination of many specimens from Australasia in a future work will settle this question. For now, we prefer to follow the data we have and associate the two kinds of females examined to the males collected at the same areas.

Another important bit of information on this question was given by Zhu et al., 2003. They redescribed females (fig. 59A–G) and males (fig. 60A–G) of “ T. chauliodus ” and gave a handful of records from Yunnan and Hainan provinces, China, besides describing a new species, T. zhangfu Zhu et al. 2003 (fig. 107A–I), also from Yunnan, China. They misidentified the male of T. chiyokoae new species as T. chauliodus , probably following Okuma (1988b) and Tanikawa (1990), describing the actual T. chauliodus male as T. zhangfu . After examining photos of T. zhangfu holotype ( Fig. 11 D–G), we concluded that it has small differences on chelicerae and genitalia, but it clearly belongs to the real T. chauliodus , matching well with photos of the male lectotype of this species ( Fig. 11A, B ). Therefore, we herein synonymize T. zhangfu Zhu et al. 2003 with T. chauliodus Thorell, 1890 new synonymy.

MAP 2. Distribution of T. megalocera new species and the first record of T. chauliodus for the Neotropics.

The female Zhang et al. (2003) associated to the male of T. chiyokoae new species actually belongs to T. chauliodus . The female of T. chauliodus , the male of T. chiyokoae new species (considered as T. chauliodus ) and the actual male of T. chauliodus (holotype of T. zhangfu ) have all been collected at the same locality: Meilun (or Meilong) county, Yunnan province (21°54’N, 101°12’E). For the best of our knowledge, this is the only area where both species have been collected together.

Finally, it is important to highlight that due to the terrible fire that destroyed MNRJ collection, the one and only male specimen of T. chauliodus we collected was destroyed. Because photos were previously taken (except the detailed SEM photos), it was possible to proceed with its redescription above. Furthermore, despite the strong collecting effort at the type-locality throughout the last three years during a yet unpublished taxonomic survey in Reserva Ecológica de Guapiaçu, Rio de Janeiro state, Brazil, we were not able to collect any other specimens of T. chauliodus .

Distribution. This species is originally recorded from Asia, ranging from China in the North to Malaysia and Singapore in the Southeast, and also Papua New Guinea in Oceania, after Okuma (1987). In the Neotropical region, the first and only record of this species is from Reserva Ecológica de Guapiaçu, Cachoeiras de Macacu, Rio de Janeiro state, Brazil (Map 2). Additionally, the record given by Okuma (1988b) for Philippines may be correct, but we have not been able to examine specimens from this country. The collection of this species in Brazil may indicate that is has a larger but still undocumented distribution throughout the world.

Figures

FIGURE 7. Tetragnatha chiyokoae new species male holotype: A, dorsal habitus. B–D, left chelicera; B, upper view. C, inner view. D, lower view. E–G, left palp; E, mesal view. F, dorsal view. G, ventral view (paracymbium). Scale bars, A, 2 mm; B, C, D, 0.5 mm; E, F, G, 0.2 mm. Photos, Feng Zhang.

FIGURE 8. Tetragnatha chiyokoae new species female paratype (NSMT-Ar 17244): A, B, left chelicera; A, upper view. B, lower view. * = midway conspicuous concavity. Photos, Akio Tanikawa.

FIGURE 9. Tetragnatha chauliodus male (MNRJ 7518): 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 palp; H, mesal view. I, dorsal view. J, ventral view (paracymbium). Scale bars, A, B, C, 2 mm; D, E, F, G, H, I, J, 0.2 mm.

FIGURE 10. Tetragnatha chauliodus female (UFRJ 1313): 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, genital fold, ventral view. Scale bars, A, B, C, 2 mm; D, E, F, G, H, 0.2 mm.

FIGURE 11. Tetragnatha chauliodus. A–B, male lectotype (NHRS: GULI000070711): A, left chelicera, upper view. B, right chelicera, upper/inner view. C, female paralectotype (NHRS: GULI000070711), left chelicera, lower view. D–G, T. chauliodus sub T. zhangfu, male holotype: D–E, left chelicera: D, upper view. E, lower view. F–G, left palp: F, mesal view. G, dorsal view. Scale bars, D, E, F, G, 0.2 mm.

FIGURE 13. Tetragnatha tenuissima female: A, dorsal habitus (UFRJ 1534). B, lateral habitus (UFRJ 1534). C, ventral habitus (UFRJ 1534). D–G, left chelicera (UFRJ 1534); D, upper view. E, inner view. F, lower view. G, outer view. H–I, female genitalia; H, genital fold, ventral view (UFRJ 1534). I, internal genitalia, dorsal view (UFRJ 1520). Scale bars, A, B, C, 2 mm; D, E, F, G, 0.5 mm; H, 0.2 mm; I, 0.1 mm.

FIGURE 14. Tetragnatha tenuissima new species SEM photos: A–B, male left chelicerae (MPEG 031350); A, upper view. B, lower view. C–D, female left chelicerae (UFRJ 1534); C, upper view; D, lower view. E–G, left male palp (MPEG 031349); E, mesal view. F, embolus detail, ventral view. G, paracymbium detail, ventral view. H, epiandrous detail, ventral view (MPEG 031350). Scale bars, A, B, C, D, E, 0.2 mm; F, H, 0.02 mm; G, 0.1 mm.