Orsinome, THORELL, 1890

Álvarez-Padilla, Fernando & Hormiga, Gustavo, 2011, Morphological and phylogenetic atlas of the orb-weaving spider family Tetragnathidae (Araneae: Araneoidea), Zoological Journal of the Linnean Society 162 (4), pp. 713-879 : 791-794

publication ID

https://doi.org/ 10.1111/j.1096-3642.2011.00692.x

DOI

https://doi.org/10.5281/zenodo.10545816

persistent identifier

https://treatment.plazi.org/id/7D5E87AD-C027-5556-FE84-4C25D287F9E6

treatment provided by

Valdenar

scientific name

Orsinome
status

 

ORSINOME THORELL, 1890 View in CoL View at ENA

( FIGS 5A, B View Figure 5 , 91B, D View Figure 91 , 96–104 View Figure 96 View Figure 97 View Figure 98 View Figure 99 View Figure 100 View Figure 101 View Figure 102 View Figure 103 View Figure 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 View Figure 101 ); 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 View Figure 102 , 104E View Figure 104 ); male cephalothorax ocular area higher than lateral margins ( Fig. 101B, D View Figure 101 ); embolus base resting on the subtegulum ( Fig. 104A View Figure 104 ); and having the dorsobasal process of the cymbium made of a cuticular fold that extends to the middle of the cymbium ( Fig. 103C View Figure 103 ).

Description: Female: body length c. 14.0 mm. Femora IV trichobothrial shaft not branched ( Fig. 101G View Figure 101 ). Ocular area lower than carapace lateral margins ( Fig. 101B View Figure 101 ). Labium trapezoidal, wider than long and rebordered. Sternum longer than wide ( Fig. 101C View Figure 101 ). Anterior surface of chelicerae smooth; boss present ( Fig. 101F View Figure 101 ). 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 View Figure 100 ). Tracheal spiracle near the spinnerets. Median tracheae not ramified, longer than half the lateral tracheae length, with leaf-shaped tips ( Fig. 100A, C View Figure 100 ). ALS with an extensive field of piriform spigots ( Fig. 100B View Figure 100 ). 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 View Figure 100 ). 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 View Figure 100 ). Epigynal plate flat, copulatory openings ventrally orientated. Spermathecae walls weakly sclerotized ( Figs 100B View Figure 100 , 104E View Figure 104 ). 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 View Figure 104 ).

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 View Figure 101 ). 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 View Figure 100 ). 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 View Figure 103 ). Cymbial dorsobasal process fused to the cymbium more than two thirds of its length ( Fig. 103C, D View Figure 103 ). Tegulum roughly oval, with an ectal depression produced by the displaced subtegulum ( Fig. 104A, B View Figure 104 ). Conductor parts well sclerotized, attachment to tegulum membranous ( Fig. 104C, D View Figure 104 ). 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 View Figure 104 ). Embolus approximately as long as the cymbium, thin and well sclerotized ( Fig. 104C View Figure 104 ). Sperm duct with more than five coils ( Fig. 104B View Figure 104 ).

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 View Figure 5 ). 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 View Figure 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 View Figure 96 ); paracymbium cylindrical, longer than half the cymbium length and with a basal apophysis ( Fig. 97E View Figure 97 ); and median tracheae not ramified ( Fig. 97F View Figure 97 ). All other studied morphological

794 F. ÁLVAREZ-PADILLA and G. HORMIGA features are similar to Nanometa sp. and ‘ Nanometinae sp.’ ( Figs 91B, D View Figure 91 , 96–99 View Figure 96 View Figure 97 View Figure 98 View Figure 99 ). The relationships of Orsinome to other Leucauginae genera are unresolved by the data set of morphology plus behaviour ( Fig. 143A, B View Figure 143 ); however when these data are combined with DNA sequences O. cf. vethi is placed as sister to Tylorida ( Fig. 144 View Figure 144 ).

Kingdom

Animalia

Phylum

Arthropoda

Class

Arachnida

Order

Araneae

Family

Tetragnathidae

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