Bioacoustics of Nanometa gentilis

DESCRIPTION: Male (GH0114): Total length ca. 2.6 (cephalothorax and abdomen detached). Cephalothorax length 1.1, width 0.8. Clypeus height 1.0 AME diameter. Cephalothorax background pale yellow with pattern of pair of dark gray parallel lines that converge in the fovea and the carapace lateral edges. Endites and sternum color dark brown. Cheliceral promargin and retromargin with three and two teeth respectively, cheliceral denticles present. Abdomen dorsum background light gray, silvery guanine patches conspicuous and covering the anterior half of abdomen except medial line, lateral surface covered with guanine patches over dorsal half, ventral half with brown pattern, ventral surface with a central brown rectangle, flanked by a line of silvery guanine patches. Stridulatory organ formed by a cuticular ridge highly sclerotized on booklung anterior edge, coxa IV retrolateral not examined with SEM. Femur I length 2.0. CEMP square in shape and ca. 1/4 of the cymbium length. Conductor distal apophyses surface smooth, tip C-shaped (figs. 7B, F, H, 8A–C). Female (WAM T24691, T24689): Total length 4.0. Clypeus height approximately the same as the AME (measurements taken from Simon, 1908 , description). Cephalothorax and abdomen coloration darker than in male (fig. 7A, C). Epigynum plate one third wider than long, anterior margin rounded (figs. 7E, 8D).

DESCRIPTION: Female total length 2.3–8.8. Cephalothorax length 0.9–3.6, width 0.7–2.7. Carapace glabrous, background pale yellow to brown, cephalic region dark gray or brown, darker coloration tapering toward fovea, carapace margins outlined by the same pattern covering the cephalic region (figs. 9A, 18A, 36A). Fovea deep, triangular in shape or as a transverse line, carapace dorsal pits absent. Clypeus height 0.9–2.7 AME diameter, cuticle darker below median eyes and paler below lateral eyes (figs. 9G, 36I, J). AME slightly larger than PME; except in N. purpurapunctata , which has reduced AME. Lateral eyes juxtaposed on a tubercle (separated in N. purpurapunctata ), one AME diameter apart from median eyes and approximately half that size. Chelicerae with few scattered setae, cuticle smooth, without ventral stridulatory ridges. Promargin with three teeth, retromargin with none to two, cheliceral denticles present. Endites longer than wide, dark brown, internal margins lighter in coloration. Labium rectangular, wider than long, colored as endites. Sternum yellowish to dark brown, trapezoidal in shape, wider between first two legs (figs. 9E, 18C, 21E). Abdomen dorsum covered with silvery guanine patches, background either brown or gray. Silvery guanine patches in small species cover the entire abdominal dorsum giving a shiny appearance; larger species’ patches are isolated in spots giving a less shiny appearance when alive (figs. 9A, 14A, 36A). Venter with a central dark longitudinal rectangle flanked by two parallel lines of guanine patches (figs. 9E, 18C, 20E) (pattern less conspicuous in Nanometa tasmaniensis : fig. 21E). Lateral surfaces with either a complete longitudinal area of guanine patches, or this area interrupted with a reticulated pattern either dark gray or dark brown (figs. 9C, 26C, 36E). Booklung covers without stridulatory organs, except in N. sarasini (fig. 14H). Spinnerets pale gray to brown, lighter pattern on internal surfaces. Leg formula 1-2-4-3; femur I length 1.1–6.9; first pair considerably larger, all leg segments from pale yellow to dark brown, decorated with transverse darkbrown lines or dark spots, except in N. fea which has all legs entirely dark brown (fig. 15C). Femora with few setae, other segments increasingly hirsute after tibiae. Macrosetae few and present on all segments except tarsus. Epigynum flat, rectangular in shape and wider than long; copulatory openings visible in ventral view and located laterally on the epigynal plate (figs. 10A, B, 11A, B, 14D); size and shape of these openings are species diagnostic. Copulatory ducts modified as membranous sacs that connect to spermathecae via two longitudinal sclerotized ducts (fig. 13E). Spermathecae sclerotization variable, but differentiated from the “copulatory sacs” by a cluster of accessory gland ducts (figs. 20H, 23C, D). Fertilization ducts short, well sclerotized, and originating near the cluster of accessory gland ducts (figs. 13E, 23C). Male same as female except as noted. Total length 2.0–8.1. Cephalothorax length 1.0–3.2, width 0.8–2.0. Carapace dorsal coloration lighter than female. Clypeus height 1.0–1.5 AME diameter. Chelicerae slightly longer and narrower apically, dorsal cuticle smooth, becoming rugose toward ectal and apical surfaces (figs. 9I, 14I, 26I); ventral cuticle without stridulatory organs (fig. 21H). Abdomen pattern as in female but lighter. Legs: Femur I length 1.6–10.1. Coloration and patterns weaker than in female. Pedipalp: Tibia triangular in shape and usually longer than wide, 1.4–3.75 times, apical margin wider (figs. 13A, 19A). CEBP with one to three apophyses, paracymbium hook or finger shaped either hirsute or glabrous; CEMP small, apical portion as a rounded blunt apophysis; cymbial distal process variable in size and shape (figs. 13C, 15D, 29C). Tegulum donut shaped and compressed dorsoventrally. Embolus and conductor attachment membranous, at the center of the tegulum (figs. 13A, B, 22A, B). Conductor spirals clockwise, margins heavily sclerotized, middle section membranous and expandible (figs. 10C–F, 13A, B). Conductor apical apophyses of variable shape (figs. 10C, D, 19A–C, 23G, H). COMPOSITION: Nanometa gentilis , N. trivittata , N. lagenifera , N. sarasini , N. purpurapunctata , N. tasmaniensis , N. fea , N. tetracaena , N. dutrorum , N. forsteri , and N. dimitrovi (all presented in the current paper), as well as the taxa formerly included in Nediphya : Nanometa hippai comb. nov. , N. lehtineni comb. nov. , N. lyleae comb. nov. , and N. padillai comb. nov. Several small sized Nanometa species remain undescribed; the species diversity of the smaller species seems to exceed that of the larger (perhaps more conspicuous and frequently collected) taxa. SYSTEMATICS: The monophyly of Nanometa is supported by the following morphological synapomorphies: branched median tracheal trunks (figs. 11D, 30D); males with a sclerotized ridge on the anterior part of the booklung cover, presumably part of a stridulatory organ with a plectrum on the fourth coxae consisting of small teeth (figs. 20F, 30C) ( Forster and Forster, 1999 ; Álvarez-Padilla and Hormiga, 2011 ); absence of embolic apophysis; conductor morphology as a curved, flattened translucent disk, with an enlarged and folded margin that covers the embolus distal part (figs. 10C, D, 11E, F, 13C); and copulatory ducts modified as sacs (figs. 9H, 11C, 13E). Kallal and Hormiga’s (2018) recent phylogenetic analysis included both large and small Nanometa species and supported the monophyly of the genus. These authors also found Pinkfloydia to be sister to a clade with remaining nanometines, with good support ( Kallal and Hormiga, 2018 ). The analysis of Dimitrov et al. (2017) suggested that Taraire (see description below) is sister to Nanometinae but with low support. Our analysis elaborates on that latter work, focusing on Nanometa and other tetragnathid taxa found in Australia , New Zealand , New Caledonia , and Papua New Guinea .

DIAGNOSIS: The internal epigynal structures of Nanometa are similar to those found in Taraire from New Zealand . The copulatory ducts of Nanometa are modified as membranous sacs and separated from the spermathecae, giving the appearance of four receptacles (figs. 9H, 11C, 13E). The accessory glands found in Nanometa and Taraire were used to homologize the spermathecae; however, these accessory glands were not discussed in the description of Nediphya ( Marusik and Omelko, 2017 ) . Nanometa species can have the eyes in two (fig. 9G, I) or three rows ( Marusik and Omelko, 2017: 1–4 , 6–8). The AME are slightly reduced in N. purpurapunctata (fig. 26G, I), but that arrangement differs considerably from Nanometa lehtineni in dorsal view, in which the PLE are enlarged ( Marusik and Omelko, 2017 : figs. 1–4). The posterior edge of the epigynum in Nanometa never extends below the epigastric furrow (fig. 10A, B), in contrast to Taraire , where the posterior edge extends beyond the epigastric furrow (fig. 47A, B). Nanometa cymbial processes can be easily homologized with those of Pinkfloydia , Taraire , and Tawhai , in addition to many tetragnathids, such as Chrysometa Simon, 1894 , Meta C. L. Koch, 1836 , Metellina Chamberlin and Ivie, 1941 , and Allende . The CEBP of Nanometa is basal to the paracymbium and usually bears one to several spines (figs. 7B, 8A, 10F, 23E, F), the CEMP is a cuticular fold distal to the CEBP either covered with normal setae (figs. 7D, 10E), armed with modified structures as in Pinkfloydia ( Dimitrov and Hormiga, 2011 : figs. 8A, 13H) or as a tiny cuticular fold in Nanometa lehtineni ( Marusik and Omelko, 2017 : figs. 38, 39). Nanometa males can be separated from those of Taraire , Tawhai , and Iamarra by the absence of basal embolic apophyses (figs. 49A–C, 54A–C, 59C, D) and by the conductor formed by a flat coiled sclerite with sclerotized margins and translucent middle section (fig. 10C); this structure is folded in the latter two genera (figs. 46A, B, 49A, 50B). Nanometa males can be further separated from other tetragnathids by the presence of a stridulatory organ on the booklung cuticle that probably interacts with several cusps on the retrolateral surface of coxa IV (figs. 20F, 26F, 30C). The small size is no longer a useful diagnostic feature for Nanometa with the addition of some of these new species ( 2.7– 9.5 mm ).