Theridium eximius, LINEAGE

Agnarsson, Ingi, 2006, A revision of the New World eximius lineage of Anelosimus (Araneae, Theridiidae) and a phylogenetic analysis using worldwide exemplars, Zoological Journal of the Linnean Society 146 (4), pp. 453-593 : 478-479

publication ID

https://doi.org/ 10.1111/j.1096-3642.2006.00213.x

persistent identifier

https://treatment.plazi.org/id/236D8D66-FF8D-FF8F-26E8-2C60FAAB67D1

treatment provided by

Felipe

scientific name

Theridium eximius
status

 

THE EXIMIUS LINEAGE

Diagnosis: Males of the eximius lineage differ from other Anelosimus in having deeply notched cymbial margins ( Figs 23A, B View Figure 23 , 29A View Figure 29 , 33A View Figure 33 ), a subterminally ridged theridiid tegular apophysis ( Figs 2B View Figure 2 , 42C View Figure 42 ), embolus-distal hematodocha grooves ( Figs 35B, H, L View Figure 35 , 36C View Figure 36 , 39B, C View Figure 39 ) and from most species by a translucent cymbial hood. Females may be difficult to diagnose from other Anelosimus , most species (excluding the domingo group and A. eximius ) differ in having strongly sclerotized copulatory ducts. They differ from the closely related Madagascar group by lacking an epigynal septum, and the epigynal scape clade (including three other American species) by lacking a scape. Females differ from the rupununi group (including the remaining American species) by entire anterior epigynal bursa.

Description: Prosoma light orange or yellow, eye region pale orange with rest of cephalic area greyish. Narrow rim around the edge of prosoma slightly darker bearing a regular row of small thickened setae. Sternum extending between coxae IV ( Fig. 24D View Figure 24 ). Sternum base colour (in alcohol) brownish-yellow, mostly covered by dusky gray dots, with a darker rim around edge and an indistinct brownish-yellow central streak. Labium separated by a seam ( Fig. 24D View Figure 24 ). Abdomen light grey to bright red (dark in alcohol), with a dark grey dorsal longitudinal notched folium ( Fig. 7G View Figure 7 ). Abdomen-prosoma stridulatory apparatus present. Colulus absent, but two colular setae present ( Fig. 31E View Figure 31 ). Leg base colour pale yellow, femur, patella and distal tip of tibia and metatarsus covered with dusky grey dots. Two parallel pale yellow streaks distally on ventral side of femur I, may be only one streak or no streak on other femora. Pedipalp with a small outgrowth of tegulum – the subconductor – at base of a lamelliform conductor; theridiid tegular apophysis large, pointed, supporting embolus, attached to the tegulum via the distal hematodocha; median apophysis medially attached to the tegulum via the distal hematodocha, interacting with hood on cymbial margin, embolus large, usually bipartite (embolus plus the embolic division b) ( Fig. 19A, B, F, G, J–L View Figure 19 ). Cymbium with a large tarsal organ, tip of cymbium weakly sclerotized, whitish in preserved specimens. Pedipalpal tibia cup shaped ( Fig. 2F View Figure 2 ) with ventral side forming a lip with the characteristic theridiid row of very long setae ( Fig. 27B, C View Figure 27 ).

Phylogenetics: The eximius lineage is the largest clade containing only New World species. The monophyly of the eximius lineage is supported by at least the following putative synapomorphies: deeply notched cymbial margin (15 -2, Figs 23A, B View Figure 23 , 29A View Figure 29 , 33A View Figure 33 ), translucent cymbial hood (25 -0), an abrupt post-SBII turn of the sperm duct (30 -1, Fig. 57D–F View Figure 57 ), subterminally ridged theridiid tegular apophysis (56 -1, Figs 2B View Figure 2 , 42C View Figure 42 ), and embolus-dh grooves (69 -1, Figs 35B, H, L View Figure 35 , 36C View Figure 36 , 39B, C View Figure 39 ). The Madagascar group is sister to the eximius lineage .

Composition: The eximius lineage contains 20 species: A. analyticus , A. arizona , A. baeza , A. chickeringi , A. domingo , A. dubiosus , A. elegans , A. eximius , A. fraternus , A. guacamayos , A. jabaquara , A. jucundus , A. octavius , A. oritoyacu , A. pacificus , A. pantanal , A. puravida , A. studiosus , A. tosum and A. tungurahua .

Distribution: New World, from north-eastern USA to Argentina ( Fig. 63A View Figure 63 ). Most speciose in Ecuador and Mexico, particularly at altitudes of 1000 m or above.

Natural history: All studied eximius lineage species are social; for an overview of the natural history of social species see under Anelosimus above.

Kingdom

Animalia

Phylum

Arthropoda

Class

Arachnida

Order

Araneae

Family

Theridiidae

Genus

Theridium

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