Sidymella hirsuta (L. Koch, 1874)

Machado, Miguel & Teixeira, Renato Augusto, 2021, Phylogenetic relationships in Stephanopinae: systematics of Stephanopis and Sidymella based on morphological characters (Araneae: Thomisidae), Organisms Diversity & Evolution (New York, N. Y.) 21 (2), pp. 281-313 : 294

“hirsuta clade ”

The “ hirsuta clade” is formed by spiders that resemble Epicadinus by their “spiny” habitus, with long and needle-shaped setae covering their entire prosoma (Char. 11, state 0 and 2), opisthosoma (Char. 80, state 1; see Fig. 21h ) and legs. The group was supported by 10 homoplastic characters and one synapomorphy: RTAvbr spoon-shaped(Char. 106, state 3; see Fig. 19e ). Because of how the characters were treated in our analyses, this ambiguous feature was not shown along the branch on the working phylogenetic hypothesis. Nevertheless, the emergence of the genus by itself is held by strong branch supports ( Fig. 3 ) and good nodal stability ( Fig. 2 ). As observed in Stephanopis , the male palp architecture of species of the “ hirsuta clade” is characterized by the presence of a RTAvbr, well-developed CP, oval-shaped tegulum and filiform embolus meandering at its distal portion (whip-like). The arrangement and shape of copulatory structures of females, although slightly different from those of Stephanopis , also show some degree of resemblance. Females of the “ hirsuta clade” have flattened, narrowed and tubular copulatory ducts (Char. 86, state 0; Fig. 16e, g ) and spermathecae significantly longer than those of Stephanopis . Despite having an opisthosoma with a pair of “protruding corners” (dorsolateral projections), a feature considered by Koch (1874) to justify the original description of Si. hirsuta in Sidymella , other somatic characters (e.g. number and arrangement of tibial and metatarsal macrosetae; disposition of teeth of the tarsal claws) wildly differ from those of the species type of this genus. The relationship of the “ hirsuta clade” with the clade composed of the “ Epicadus group” and ( Coenypha + Sidymella ) was based on three highly homoplastic characters, each presenting numerous state reversals. Moreover, both Bremer indexes and symmetric resampling analyses presented low support values for this more inclusive clade ( Fig. 3 ) as well as sensitivity analyses showing weak nodal stability in this section of the topology ( Fig. 2 ). Such results, along with the unpredictable behaviour of the clade, suggest that the placement of the “ hirsuta clade” is particularly arguable. Similarities and shared characters between this group and Stephanopis , in addition to their coincident geographical distribution, must also be considered as evidence that the placement of the “ hirsuta clade” with most Neotropical stephanopine genera sampled in this study is questionable and most likely to be spurious.

Figures

Fig. 21 Characters relative to the male genitalia of specimens sampled in the present analysis: a Stephanopis barbipes, left palp. b Isala cambridgei comb. nov., left palp. c Onocolus intermedius, left palp. d Sidymella longispina, left palp. e Paratobias sp. 1, left palp. f Tmarus polyandrus, left palp. g Stephanopis altifrons, left palp (lower arrows indicate the pair of ventral filamentous setae on tibiae). h Stephanopis bicornis, retrolateral view of left palp (detail of the cymbial setae brush)

Fig. 19 Characters relative to the male genitalia of specimens sampled in the present analysis: a Epicadus trituberculatus, left palp. b Stephanopis pentacantha, left palp (arrow indicates the prolateral macrosetae). c Geraesta hirta, left palp. d Sidymella lucida, retrolateral view of left palp.e Borboropactus nyerere, left palp. f Isala cambridgei comb. nov., retrolateral view of left palp. g Stephanopis nigra, retrolateral view of left palp. h Stephanopis altifrons, detail of the RTA

Fig. 3 Clade supports obtained by relative Bremer index (above the branches) and symmetric resampling analysis (below the branches). A colour scheme is applied to represent the geographical distribution of the clades represented on the working phylogenetic hypothesis

Fig. 2 Hypothetical reconstruction of the relationships of Stephanopis and Sidymella based on the strict consensus of the most congruent tree (K = 17.89) obtained after implied weighted analysis. Nodal stability is represented by the “Navajo rugs” along the branches (analysis recovering

Fig. 16 Characters relative to opisthosoma of specimens sampled in the present analysis: a Stephanopis nana. b Stephanopis monulfi. c Sidymella hirsuta, d Stephanopis altifrons, cuspidate surface. e Tmarus elongatus, mazed-surface. f Isala rufiventris comb. nov., granular surface. g Isala punctata comb. nov., fingerprint surface. h Sidymella hirsuta, needle-shaped and filamentous setae