Orsinome THORELL 1890
Creators: name: Álvarez-Padilla, Fernando
name: Hormiga, Gustavo
Publisher: name: Zenodo
Year: 2011
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Arachnida
Araneae
Tetragnathidae
Orsinome

description: ORSINOME THORELL, 1890   
(FIGS 5A, B, 91B, D, 96–104)  
 Type species: Orsinome vethii (Hasselt, 1882). The type specimen depository of Pachygnatha vethii is unknown to us.   
 Diagnosis: Orsinome species can be distinguished from other tetragnathids by the following combination of characters: femora IV with trichobothria (Fig. 101G); female chilum present; copulatory ducts well sclerotized and coiled; copulatory openings inside a common chamber on the centre of the epigynal plate (Figs 102A–D, 104E); male cephalothorax ocular area higher than lateral margins (Fig. 101B, D); embolus base resting on the subtegulum (Fig. 104A); and having the dorsobasal process of the cymbium made of a cuticular fold that extends to the middle of the cymbium (Fig. 103C).   
 Description: Female: body length c. 14.0 mm. Femora IV trichobothrial shaft not branched (Fig. 101G). Ocular area lower than carapace lateral margins (Fig. 101B). Labium trapezoidal, wider than long and rebordered. Sternum longer than wide (Fig. 101C). Anterior surface of chelicerae smooth; boss present (Fig. 101F). Secondary eyes with canoe-shaped tapetum. Eyes subequal in size, lateral eyes slightly smaller, juxtaposed, and on a tubercle. Clypeus almost twice one AME diameter. Abdomen cylindrical, covered with silver guanine patches (Murphy & Murphy, 2000: fig. 10). Booklung cuticle smooth (Fig. 100A). Tracheal spiracle near the spinnerets. Median tracheae not ramified, longer than half the lateral tracheae length, with leaf-shaped tips (Fig. 100A, C). ALS with an extensive field of piriform spigots (Fig. 100B). PMS with three aciniform spigots between the cylindrical and minor ampullate silk gland spigots but without any aciniform spigots over the anterior surface (Fig. 100G). PLS with c. 22 aciniform spigots arranged in roughly parallel lines, distal end of the aggregate spigots embracing the tip of the flagelliform spigot (Fig. 100D). Epigynal plate flat, copulatory openings ventrally orientated. Spermathecae walls weakly sclerotized (Figs 100B, 104E). Copulatory and fertilization ducts coiled, longer than the spermatheca length with well-sclerotized cuticle. Accessory concentrated near the duct junction, accessory glands acorn-shaped and in individual pits (Fig. 104B–F).   
 Male: size and somatic morphology similar to that of the female, except the chelicerae are considerably larger, with a massive median apophysis on the internal margins (Fig. 101H). PLS triplet reduced to nubbins. Epiandrous plate well sclerotized, fusules immersed in a transverse groove with their bases wider than the fusule shaft (Fig. 100F). Palpal patella without macrosetae. Palpal femora very long, more than four times its width. Tibia length twice its width. Paracymbium shorter than half the cymbium length, curved, with swollen distal margin (Fig. 103F). Cymbial dorsobasal process fused to the cymbium more than two thirds of its length (Fig. 103C, D). Tegulum roughly oval, with an ectal depression produced by the displaced subtegulum (Fig. 104A, B). Conductor parts well sclerotized, attachment to tegulum membranous (Fig. 104C, D). Embolus base rectangular and longer than wide, located between tegulum and cymbium. Embolus displaced between the tegulum and cymbium with its distal part resting on the subtegulum (Fig. 104A). Embolus approximately as long as the cymbium, thin and well sclerotized (Fig. 104C). Sperm duct with more than five coils (Fig. 104B).   
 Natural history: Orsinome includes 17 described species distributed in the South-East Asian tropics and Madagascar (Thorell, 1890; Chrysanthus, 1971; Zhu et al., 2003). They build horizontal webs, with c. 20 spirals, c. 13 radii, and open hubs (Fig. 5C). Their webs are found over the water between the rocks, and over vegetation along rivers.   
 Taxonomy: Two species are included in this analysis, Orsinome cf. vethi and ‘ Orsinome ’ sarasini Berland, 1924, but the results of our analysis suggest that they are not congeneric. The first species belongs to the leucaugines, whereas ‘ Orsinome ’ sarasini belongs to Nanometinae (Fig. 144). The taxonomic status of ‘ O. ’ sarasini should be revised when a larger taxonomic sample of these Australasian lineages is studied in more depth. A new genus name is required for this lineage of species from New Caledonia, South-eastern Australia, and Tasmania (Urquhart, 1891; Berland, 1924). ‘ Orsinome ’ sarasini differs from the taxa in Nanometinae by the following characteristics: distal end of aggregate spigots embracing the distal end of flagelliform spigot (Fig. 96C); paracymbium cylindrical, longer than half the cymbium length and with a basal apophysis (Fig. 97E); and median tracheae not ramified (Fig. 97F). All other studied morphological   
 794 F. ÁLVAREZ-PADILLA and G. HORMIGA features are similar to Nanometa sp. and ‘ Nanometinae sp.’ (Figs 91B, D, 96–99). The relationships of Orsinome to other Leucauginae genera are unresolved by the data set of morphology plus behaviour (Fig. 143A, B); however when these data are combined with DNA sequences O. cf. vethi is placed as sister to Tylorida (Fig. 144).
description: Published as part of Álvarez-Padilla, Fernando & Hormiga, Gustavo, 2011, Morphological and phylogenetic atlas of the orb-weaving spider family Tetragnathidae (Araneae: Araneoidea), pp. 713-879 in Zoological Journal of the Linnean Society 162 (4) on pages 791-794, DOI: 10.1111/j.1096-3642.2011.00692.x, http://zenodo.org/record/5440885