Micrathena undetermined

Magalhães, Ivan L. F. & Santos, Adalberto J., 2012, Phylogenetic analysis of Micrathena and Chaetacis spiders (Araneae: Araneidae) reveals multiple origins of extreme sexual size dimorphism and long abdominal spines, Zoological Journal of the Linnean Society 166 (5), pp. 14-53 : 21

MICRATHENA SPECIES GROUPS

Considering the internal phylogeny of Micrathena , two great subdivisions were recovered ( Fig. 8 ). The first group, hereafter named clade M. swainsoni , is formed by the M. triangularispinosa , M. militaris , and M. spinosa groups (sensu Levi, 1985) and is supported by the loss of the tapetum in the posterior median eyes (char. 25: 1), a sclerotized plate anterior to the epigynum (char. 73: 1), and by a laterally projected paracymbium (char. 140: 1) ( Fig. 8 ). The second, hereafter denominated the M. clypeata clade, is formed by Chaetacis and the remaining Micrathena species groups ( M. gracilis , M. funebris , M. pungens , M. lepidoptera , M. kirbyi , and M. guerini, sensu Levi, 1985 ) and is supported by four non-ambiguous synapomorphies ( Fig. 8 ): wrinkled booklung covers (which are also modified into stridulatory files; char. 70: 0; char. 71: 1), epigynum with a pair of anterior apodemes (char. 75: 1), copulatory openings small and concealed beneath lateral plates (char. 84: 1), and terminal apophysis fused to the embolus (char 114: 1). Most species groups proposed by Levi (1985) are monophyletic, excluding the M. militaris group (paraphyletic in relation to the M. spinosa group) and the M. kirbyi and M. guerini groups (which are not mutually monophyletic). Therefore, to increase agreement between taxonomy and phylogeny, we here propose a new, natural classification scheme for Micrathena groups ( Figs 7–9 ; see Discussion and Taxonomy below).

Figures

Figure 7. Character optimizations of the discrete data set in the tree obtained through implied-weighted parsimony (k = 5). Character numbers are indicated above circles and character states are indicated below circles. Filled circles indicate convergence-free apomorphies, open circles represent homoplasious synapomorphies. For character descriptions, see Appendix 1. The grids near the nodes represent a sensitivity analysis using different values of k; open cells represent presence of the corresponding clade in a given weighting scheme, whereas filled cells represent its absence. Different Micrathena species groups are indicated by the alternating background colour. Scale bar = 2.0 mm. All spiders (females at left, males at right) drawn to scale and printed approximately at natural sizes. Continued in Figs 8 and 9.

Figure 8. Fig. 7 continued. Scale bar = 2.0 mm.

Figure 9. Fig. 8 continued. Scale bar = 2.0 mm.