Metleucauge, LEVI 1980

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 : 782-786

METLEUCAUGE LEVI 1980 ( FIGS 4D , 77–81 )

Type species: Metleucauge eldorado Levi 1980 . The holotype of M. eldorado is a female specimen from California ( USA), deposited at the Museum of Comparative Zoology , Harvard University (not examined).

Diagnosis: Metleucauge species can be distinguished from all other tetragnathid genera by the following combination of characters: cephalic fovea of both sexes resembling two deep pits ( Fig. 78A ); femora without trichobothria ( Fig. 78E ); epigynum flat with two deep atria ( Fig. 79A, B ); spermathecae weakly sclerotized ( Figs 79C, D , 81D ); ( Fig. 78G, H ); male palpal trochanter with a large distal apophysis, palpal femora and tibia longer than four times its width, almost half the carapace length ( Fig. 78F ); cymbial dorsobasal process and cymbial ectomedian process present ( Fig. 80B, E ); and conductor subdivided ( Fig. 81A, B ).

Description: Female: body length c. 11.0 mm. Ocular area lower than carapace lateral margins ( Fig. 78C ). Labium trapezoidal, wider than long and rebordered. Sternum longer than wide ( Fig. 78B ). Anterior surface of chelicerae smooth; boss present ( Fig. 78C, G ). Secondary eyes with canoe-shaped tapetum ( Levi, 1980: figs 139, 140). Eyes subequal in size, lateral eyes slightly smaller, juxtaposed and on a tubercle. Clypeus c. 1.5 times the AME diameter. Booklung cuticle smooth ( Fig. 77A ). Tracheal spiracle near the spinnerets, without accessory glands ( Fig. 77D ). Median tracheae not ramified, tips leaf-shaped ( Fig. 77C, F ). ALS with an extensive field of piriform spigots ( Fig. 77B ). PMS with five aciniform spigots between the cylindrical and minor ampullate silk gland spigots but without any aciniform spigots over the anterior surface ( Fig. 77G ). PLS with c. 25 aciniform spigots arranged in roughly parallel lines; distal end of aggregate spigots embracing tip of flagelliform spigot ( Fig. 77E ). Epigynal plate flat, copulatory openings ventrally orientaed. Spermathecae walls weakly sclerotized ( Fig. 79A–D ). Copulatory and fertilization ducts shorter than the spermatheca length and cuticle well sclerotized. Fertilization ducts curved, but not coiling around the copulatory ducts. Accessory glands evenly distributed over the spermathecae, with gland openings arranged in groups ( Fig. 79C, D ).

Male: size and somatic morphology similar to that of the female, except the chelicerae are longer and their anterior cuticle is rugose ( Fig. 78D, H, F ). PLS triplet reduced to nubbins. Epiandrous plate flat, fusules arranged in an irregular line of clusters, fusules not immersed in pits ( Fig. 77F ). Palpal patella with one macroseta ( Fig. 78D ). Paracymbium rectangular, with a basal apophysis, and considerably shorter than the cymbium length ( Fig. 80B ). Tegulum roughly oval, with an ectal depression produced by the displaced subtegulum ( Fig. 80A ). Both conductor parts are well sclerotized; one presents a translucent membranous process ( Fig. 81A, B ). Conductor attachment to tegulum and between its two parts membranous. Embolus base rectangular, longer than wide; embolus roughly the same length as its base, well sclerotized ( Fig. 81C ). Sperm duct path with fewer than three coils ( Fig. 81C ).

Natural history: There are seven described species of Metleucauge , with a geographical distribution on both sides of the Pacific ( Levi, 1980; Tanikawa, 1992; Zhu et al., 2003). These spiders build horizontal webs with open hubs, fewer than ten radii and spirals ( Fig. 4D ). Their webs are spun between rocks or near streams ( Levi, 1980; G. Hormiga, pers. observ.). Little is known about the biology of Metleucauge species , but a

784 F. ÁLVAREZ-PADILLA and G. HORMIGA pioneering study by Yoshida (1989) documented and compared the feeding behaviours and prey composition for three Japanese species.

Taxonomy: Both the Asian and North American species of Metleucauge have been studied relatively recently ( Levi, 1980; Tanikawa, 1992; Tanikawa & Chang, 1997); however the monophyly of this genus remains untested. Our diagnosis and description are based on M. eldorado specimens and the illustrations of the species described by Tanikawa (1992). The specimens that we coded for the phylogenetic analysis belong to M. eldorado . Tanikawa’s (2001) phylogenetic analysis proposed Metleucauge chikunii Tanikawa, 1992 as sister to a clade formed by a large sample of leucaugines. Support for Tanikawa’s hypothesis was provided by three synapomorphies: presence of cymbial processes other than the paracymbium, seminal receptacles of the female not sclerotized, and a deep thoracic groove ( Tanikawa, 2001; Fig. 8B ). Both our data sets recovered Metleucauge as sister to a clade that includes Metabus , Orsinome , Tylorida , Mesida , Opadometa , and Leucauge ( Figs 143A, B , 144 ).

MOLLEMETA ÁLVAREZ- PADILLA, 2007

( FIGS 4E , 82–86 )

Type species: Mollemeta edwardsi ( Simon, 1904) . The holotype of Landana edwardsi is a female from Chile deposited at the Museum National d’Histoire Naturelle , Paris (examined) .

Diagnosis: Mollemeta can be distinguished from other tetragnathids by the following combination of characters: epigynum with a small spherical scape; copulatory openings located in deep curved groves ( Fig. 84A–C ); cymbial ectobasal process and cymbial ectomedian process present ( Fig. 85C ); male palpal femora and tibia longer that four times its width, approximately half the carapace length ( Fig. 83E ); paracymbium cone-shaped, much shorter than the cymbial ectobasal process ( Fig. 85C ); tegulum reduced to a narrow ring ( Fig. 86A–C ); membranous conductor ( Fig. 86C ); and embolus without basal apophyses ( Fig. 85F ).

Description: Female: body length c. 10.0 mm. Thoracic fovea transverse and deep ( Fig. 83A ). Ocular area higher than carapace lateral margins ( Fig. 83G ). Labium trapezoidal, wider than long and rebordered. Sternum longer than wide ( Fig. 83F ). Anterior surface of chelicerae smooth; boss present ( Fig. 83C ). Secondary eyes with canoe-shaped tapetum. Eyes subequal in size, lateral eyes slightly smaller, juxtaposed, and on a tubercle. Clypeus c. 1.5 times the AME diameter. Booklung cuticle grooved ( Fig. 82B ). Tracheal spiracle near the spinnerets, with accessory glands ( Fig. 82C ). Median tracheae not ramified, tips leaf-shaped ( Fig. 82D, F ). ALS piriform spigots bases rounded ( Fig. 82E ). PMS with three aciniform spigots between the cylindrical and minor ampullate silk gland spigots but without any aciniform spigots over the anterior surface. PLS with c. 25 aciniform spigots arranged in roughly parallel lines; distal end of aggregate spigots embracing tip of flagelliform spigot ( Álvarez-Padilla, 2007: fig. 9L, M). Epigynal plate flat ( Fig. 84A, B ), copulatory openings posteriorly orientated ( Fig. 86D ). Spermathecae walls well sclerotized. Copulatory ducts coiled, longer than the spermatheca diameter ( Fig. 84C ). Fertilization ducts path straight, slightly longer than spermatheca, with well-sclerotized cuticle ( Fig. 84F ). Accessory glands concentrated over the anterior surface of spermathecae, gland openings arranged in groups ( Fig. 84C–E ).

Male: size and somatic morphology similar to that of the female ( Fig. 83B, D, E ). PLS triplet reduced to nubbins ( Álvarez-Padilla, 2007: fig. 9N). Epiandrous plate flat, fusules arranged in an irregular line of fusules clusters, fusules not immersed in pits ( Fig. 82G ). Palpal patella with one macroseta. Conductor membranous, with rigid edges. Conductortegulum attachment membranous ( Fig. 86A, C ). Embolus base rectangular and slightly longer than wide; embolus almost as long as the cymbium, well sclerotized ( Figs 85D–F , 86A ). Sperm duct path with one loop before reaching fundus ( Fig. 86B ).

786 F. ÁLVAREZ-PADILLA and G. HORMIGA

Natural history: Mollemeta is a monotypic genus endemic to Chile. These spiders build vertical webs, longer than wide, with a closed hub, with more than 30 spiral turns and radii. The webs of Mollemeta are spun over tree trunks ( Fig. 4E ).

Taxonomy: The monotypy of this genus was based on the results of a previous cladistic analysis that recovered M. edwardsi as sister to a clade that contains the genera Meta , Metellina , Dolichognatha , Allende , and Chrysometa ( Álvarez-Padilla, 2007) . This sister group relationship was supported by a single synapomorphy, the paracymbium on the base of the cymbial ectobasal process. The morphological + behavioural data set recovered Mollemeta as sister to a clade that includes Metainae, Nanometinae , Tetragnathinae , Chrysometa , and Allende ( Fig. 143A ); when these data were combined with DNA sequences, Mollemeta was placed as sister to a clade that includes Allende plus Tetragnathinae ( Fig. 144 ).

Figures

Figure 4. Webs of tetragnathids: A, Mesida argentiopunctata from Noosa National Park, Australia (37 cm horizontal) (Leuc004b). B, Metabus ebanoverde from Ébano Verde Natural Reserve, Dominican Republic (72 cm horizontal) (DSCN7567). C, Meta menardi from Zealand, Denmark (15 cm horizontal, photograph by Nikolaj Scharff). D, Metleucauge eldorado from California, USA (40 cm horizontal). E, Mollemeta edwardsi from Puyehue National Park, Chile (50 cm horizontal). F, Nanometa sp. from Lamington National Park, Australia (18 cm horizontal) (DSCN0492). Photographs (D) and (E) by Gustavo Hormiga.

Figure 8. Allende nigrohumeralis abdomen: A, tracheal system dorsal view (arrows pointing upwards correspond to lateral trachea and downward pointing arrows median trachea; trachea follow the same arrangement on all images). B, lateral tracheae cuticle. C, tracheal spiracle posterior view. D, detail of tracheal spiracle. E, median trachea tip. F, epiandrous fusules (arrow). Images of tracheal system (SEMFAP058), epiandrous fusules (SEMFAP057).

Figure 77. Metleucauge eldorado abdomen: A, female booklung cuticle. B, anterior lateral spinnerets. C, tracheal system dorsal view. D, tracheal spiracle posterior view. E, posterior lateral spinnerets. F, epiandrous fusules. G, posterior median spinnerets. All images from SEMFAP041, except (G) from SEMFAP075.

Figure 78. Metleucauge eldorado cephalothorax: A, female dorsal view. B, female cephalothorax ventral view and sternum. C, female tangential view. D, male anterior view. E, female femora IV ectal view. F, male cephalothorax lateral view. G, female chelicera. H, male chelicera. Female images from SEMFAP041, male images from SEMFAP075.

Figure 79. Metleucauge eldorado epigynum: A, ventral view. B, dorsal view. C and D, spermatheca and ducts. All images from SEMFAP041.

Figure 80. Metleucauge eldorado male pedipalp: A, ventral view. B, paracymbium and cymbial ectobasal process. C, dorsal view. D, apical view. E, cymbial dorsobasal process. F, conductor and embolus. All images from SEMFAP075.

Figure 81. Metleucauge eldorado illustrations: A and B, male pedipalp expanded. C, pedipalp bulb cleared ventral view. D, cleared epigynum dorsal view.

Figure 82. Mollemeta edwardsi abdomen: A, cuticle of the abdomen, close up of median lateral section. B, female booklung cuticle. C, tracheal spiracle. D, median trachea tip. E, anterior lateral spinnerets. F, tracheal system dorsal view. G, epiandrous fusules. Images (C), (D), and (F), from SEMFAP060; images (A), (B), (E), and (G), from SEMFAP043.

Figure 83. Mollemeta edwardsi cephalothorax: A, female dorsal view. B, male dorsal view. C, male chelicera. D, female chelicera. E, male tangential view. F, female ventral view. G, female tangential view. All images from SEMFAP043.

Figure 84. Mollemeta edwardsi epigynum: A, ventral view. B, posterior view. C, dorsal view. D, accessory glands. E, spermatheca. F, copulatory and fertilization ducts. Images (A) and (B), from SEMFAP043, all other from SEMFAP060.

Figure 85. Mollemeta edwardsi male pedipalp: A, ectal view. B, dorsal view. C, cymbial ectobasal process and cymbial ectomedian process. D, conductor and embolus. E, apical view. F, ventral view. All images from SEMFAP056.

Figure 86. Mollemeta edwardsi genital anatomy illustrations: A, male pedipalp ventral view. B, cleared pedipalp bulb ventral view. C, expanded pedipalp. D, cleared epigynum ventral view.

Figure 143. Strict consensus trees of parsimony analyses of the morphological and behavioural data set presented in Appendix 2: A, strict consensus cladogram of the five cladograms of minimal length obtained under equal weights of 1033 steps (consistency index = 26, retention index = 58); the consensus tree is ten steps longer. Bremer support values are given under the nodes. B, strict consensus of 11 optimal cladograms obtained with implied weights at concavities 1 to 100; the consensus tree is 101 steps longer than the equal weighted optimal cladograms. Symmetric resampling support values above 51% are given under each node. See text for additional details.

Figure 144. Preferred optimal cladogram from the study of Álvarez-Padilla et al. (2009). This tree is based on a combined analysis, using direct optimization methods, of multigene DNA sequences and the morphological and behavioural data set presented in Appendix 2. The single most parsimonious tree was 54 536 steps when all the data were analysed simultaneously. Numbers under each node correspond to the node numbers in Table 1 where all support values are plotted and the synapomorphies mapped.