Glenognatha (Jimmy Cabra-García & Antonio D. Brescovit 2016)
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Ordo: Araneae
Familia: Tetragnathidae
Name
Glenognatha Simon, 1887 – Wikispecies link – Pensoft Profile
- Glenognatha Jimmy Cabra-García, 2016, Zootaxa 4069: 16-19.
Diagnosis
Diagnosis: Males of Glenognatha resemble those of Pachygnatha by the presence of a retrolateral apophysis on the conductor (Fig. 74G). It can be distinguished from the latter genus by the paracymbium with the distal portion oriented in opposite direction to the cymbium as seen in retrolateral view (Figs. 11H, 16H, 23H, 27H, 28G, 40H, 47H, 49B, 70J, 91H, 99H, 128H), the folded retrolateral apophysis on the conductor lamina (Figs. 18B, 23F, L, 28F, 54C, 79C, 84E, 92G) and the embolus with a medial groove in its basal portion (Figs. 18B, 23O, 43D, 47H, 49F–G, 54 A, 58H, 125I). Females can be diagnosed by an anteriorly displaced tracheal spiracle (Figs. 9G, 14G, 30 A, 31G, 50G, 60C, 80G, 126C) and a tracheal system composed of two median trunks divided into numerous distal and lateral tracheoles flanked by two unbranched lateral tracheae (Figs. 12C–F, 18E–G, 24 A, 41D–F, 48G–J, 49H–J, 74I –J, 92J–L, 103F–H, 121D–G). As currently delimited, the genus Dyschiriognatha also shares these diagnostic features. Nevertheless, its synonymy with Glenognatha cannot be objectively proposed (see ‘Discussion’ section).
Description
Description: Total length 1.25–4.60 males, 1.40–4.80 females. Carapace longer than wide, 0.62–2.4 long in males and 0.61–2.05 long in females; pale yellow to dark brown (Figs. 14 A, 19 A, 38 A, 45 A, 75 A). Sternum as wide as long and prolonged between coxae in some species (Figs. 25C, 31C, 50C, 56C, 60C). Labium trapezoidal, wider than long, and rebordered. Eyes subequal in size, lateral eyes slightly smaller. Clypeus height 1.10—3.21. Chelicerae large, sexually dimorphic, with 3–5 promarginal teeth and 3–10 retromarginal teeth (Figs. 20, 46, 51, 57, 81, 86, 101, 115, 127). Cheliceral teeth numbers vary widely particularly on the retromargin, with some specimens presenting asymmetric teeth counts. Cheliceral boss well developed. Cheliceral fangs long and in some species with a well-developed retrolateral outgrowth (Figs. 39 A, 46 A, 51 A, 68B, 90E). Legs without spines (except in G. hirsutissima), slightly longer in males than in females. Femur I length varies from 0.75 to 3.45 in males and from 0.67 to 3.4 in females. Leg formula I>II>IV>III. Femora dorsal surface with one to six trichobothria (Figs. 30G, 44 A). Glenognatha foxi, G. heleios, G. iviei and G. spherella lack trichobothria on femur III and IV. Tibia dorsal surface with four to ten trichobothria (Figs. 30H, 44E). Metatarsi I, II and III, first half, with one trichobothrium longer than the diameter of the article (two in G. hirsutissima). Metatarsus IV without trichobothria except in G. florezi (one trichobothrium), G. camisea (one), G. gouldi (one), G. emertoni (one) and G. hirsutissima (two). Abdomen oval to spherical. Dorsal pattern usually with disperse silver guanine patches combined with irregular dark longitudinal bands. Lateral surface also covered with a similar pattern of guanine deposits and dark bands. Ventral surface usually with a pale black median band and irregular silver guanine patches. Posterior tracheal spiracle wider than long and anteriorly displaced. Tracheal spiracle glands occupying both sides of the atrium and the basal region of the median trunks (Figs. 12F, 24D, 41F, 48J, 83E, 92L, 103H, 129I). ALS with more than 12 piriform spigots (Figs. 17F, 24F, 30D, 55D, 63E, 64F, 103I, 121H). PMS with one to five aciniform spigot between the cylindrical and the minor ampullate spigot (Figs. 13D, 17G, 24G, 30E, 55E, 103J, 121I), nubbin posterior to the mAP. PLS with 4 to 25 AC spigots on both sexes (Figs. 13E, 17H, 24H, 30F, 49L, 63G, 103K, 121J). Females AG–FL triplet anterior to the AC spigots and almost parallel with the anterior CY spigot (Figs. 24H, 53I, 63G, 103K, 121J, 129L), except in G. florezi that lacks the triplet (Fig. 17H). PLS triplet also present in adult males (Figs. 30F, 49L, 55F, 64H, 104L), except in G. boraceia, G. lacteovittata and G. florezi (Figs. 13E, 24K). Epiandrous fusules usually four, arranged in a transverse line (Figs. 30C, 43B, 49M, 55B, 64D, 79D, 104H), although some species have up to eleven fusules such as in G. florezi (Fig. 18H). Male palpal tibia as long as wide (Figs. 91 A, 95 A, 107 A, 112 A) or longer (Figs. 47 A, 52 A, 58 A, 62 A), with three to six trichobothria on its ventral and retrolateral surfaces. Cymbium elongated with a swollen apical portion and a conspicuous tarsal organ (Figs. 18 A, 22E, 27E, 28F, 47E, 70K, 79C, 104 A). Paracymbium with two perpendicular portions, as seen in retrolateral view (Figs. 11H, 27H, 47H, 49B, 99H, 128H). Tegulum spherical, with a distal depression where the embolus and the conductor rest. Embolus surrounding the conductor base. Embolic medial groove limited to the inner surface of the embolus (Figs. 13 A, 18 A, 23D) or extended towards its outer surface (Figs. 28H, 49F, 54 A, 64B, 74F, 92F, 97 A, 109 A). Embolus surface smooth or with filiform (Fig. 23G, N, P), tooth-like (Fig. 16D, 23P) or scale-like projections (Fig. 54L). Conductor emerging from the center of the tegulum as a cylindrical tube that bends towards the center of the tegulum and flattens into a lamina. The conductor lamina has its apical portion folded and carries a conspicuous prolaterally folded retrolateral apophysis (Figs. 18B, 23F, L, 28F, 54C, 79C, 84E, 92G). Embolus partially enclosed by the apical fold of the conductor lamina and the prolaterally folded retrolateral apophysis (Figs. 18B, 23F, 28F, 43H, 70H, 79C, 97D). Female external genitalia slit-shaped with sclerotized edges. Internal genitalia haplogyne, with the following structures: a membranous chamber, a large uterus externus and a pair of copulatory ducts leading to the spermathecae (Figs. 12 A –B, 17 A –E, 23 A –C, 28 A –C, 53 A –E, 70 A –E, 92 A –E, 129 A –C). The membranous chamber has filiform projections on its lateral borders that serve as muscle attachment points (Figs. 48D, 53E). In some species the spermathecae and copulatory ducts are absent (Figs. 12 A –B, 17 A –E, 53B–E, 121 A –C) (see also Cabra-García et al. 2014). Composition:Glenognatha currently includes 27 species: G. argyrostilba (Pickard-Cambridge, 1876)n. comb.G. australis (Keyserling, 1883), G. dentata (Zhu & Wen, 1978)n. comb., G. emertoni Simon, 1887, G. foxi (McCook, 1894), G. gaujoni Simon, 1895, G. globosa (Petrunkevitch, 1925), G. gloriae (Petrunkevitch, 1930), G. heleios Hormiga, 1990, G. hirsutissima (Berland, 1935), G. iviei Levi, 1980, G. lacteovittata (Mello-Leitão, 1944), G. minuta Banks, 1898, G. smilodon Bosmans & Bosselaers, 1994, G. spherella Chamberlin & Ivie, 1936, G. tangi (Zhu, Song & Zhang, 2003)n. comb. and 11 new species described herein.
Distribution
Distribution:Glenognatha species have a broad distribution with records in Nearctic, Neotropic, Afrotropic, Indo-Malaya, Oceania and Paleartic regions. It occupies a broad altitudinal range from 6 (G. iviei) to 2,700 m. (G. florezi) (Figs. 130–138). Natural history: The biology of Glenognatha species is still poorly known and published data focus mainly on Nearctic species. Glenognatha foxi is recorded as an abundant spider in a wide variety of crops in the United States: soybean (Young & Edwards 1990; Balfour & Rypstra 1998), alfalfa (Young & Edwards 1990; Birkhofer et al. 2007, Welch et al. 2011), rice, sugarcane, peanuts, cotton (Agnew et al. 1985; Heiss & Meisch 1985; Young & Edwards 1990) and citrus (Mansour et al. 1982). Chapman et al. (2013) recorded Collembola, Aphididae and Brachycera as prey taxa for G. foxi in winter wheat. Phenology of G. foxi in Georgia was assessed by Draney (1997), who suggested a possible annual reproductive cycle with mating in the early summer. G. foxi is recorded as the most abundant aerial species in one of the two sampling stations assessed by Dean & Sterling (1985). Barrows (1919) described some aspects of the reproductive biology and habits of G. foxi. According to this author, G. foxi is common in meadows and waste-lands in hot dry situations. The mating occurs in the middle of the web with cheliceral clasp and each male palp is inserted alternately every five minutes. The overall copula lasts fifteen minutes. Nevertheless, as noted by Heiss & Meisch (1985), G. foxi also lives in moist conditions; populations in Arkansas rice crops build webs near the middle of the rice plants not far above the water. Hormiga & Döbel (1990) and Döbel et al. (1990) provided phenology and web architecture data for G. heleios. According with these authors, G. heleios is a univoltine species in intertidal salt marshes of New Jersey, with greater abundance in short and intermediate forms of Spartina alterniflora. Webs are placed close to the soil surface with the sticky spiral very closely spaced. Some aspects of the reproductive biology of G. heleios were described by Edwards & Senske (2001). These authors recorded the insertion of only one palp and a copula duration of two hours. Danielson-François (2006) carried on a detailed study of habits, sperm release patterns and reproductive behavior of G. emertoni. In this work, specimens were found in vegetation overhanging streams and under streamside rocks in Arizona. Avoidance behavior after disturbance and mating behavior were described. In the former, the spider dropped into the water beneath and floated for some distance until the extended legs allow climbed up some streamside vegetation. The mating behavior involved cheliceral clasp, vibratory courtship through legs movements and palps insertions.
Description
Glenognatha patriceae lives in the same habitats as G. mendezi (Fig. 7B). Nevertheless, this species builds its webs a few centimeters (1–5 cm) above streams (Fig. 8D). Rocks are used as attachment points (Fig. 8D). Web aggregations with shared radii and numerous hubs were commonly observed (Fig. 8E). In this structures different individuals cohabit, each occupying one hub. No aggression between conspecifics was recorded. A similar avoidance behavior, as that described for G. emertoni by Danielson-François (2006), was observed after disturbance. Diptera and Ephemeroptera were preyed during observations. A
Eberhard (1982) described the web building behavior of G. globosa from Colombia (the identification of the voucher was made after Eberhard’s original publication). This species determines the sticky spiral attachment point tapping forward with the internal leg I, holds the next radius near the attachment point with the outer leg III and IV, pushes the current segment with internal leg IV, has no temporary spiral, attaches the sticky spiral to each radius crossed, lays one radius to the frame and lefts the hub of the web intact after finishing the sticky spiral.
Taxon Treatment
- Jimmy Cabra-García; Antonio D. Brescovit; 2016: Revision and phylogenetic analysis of the orb-weaving spider genus Glenognatha Simon, 1887 (Araneae, Tetragnathidae), Zootaxa 4069: 16-19. doi
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