[Title Page] [List of Genera] Comparison of Drawings] [Regional Keys to Genera] [Descriptions of New Taxa] [Geographical Distribution] [Color Photographs] See also Catalogue of Salticidae [ Title page] List of Genera - names beginning with: A BC DEFG HIJKL MN OPQ RS TUVWXYZ References: Authors beginning with: A BC DEFG HIJKL MN OPQ RS TUVWXYZ See also Catalogue: Myrmarachne] List of species: Myrmarachne]

 

Salticidae: Diagnostic Drawings Library

by Jerzy Proszynski 2003

Genus Myrmarachne MacLeay, 1839

Remarks on relationship and definition of genus Myrmarachne (Araneae: Salticidae)

from

Jerzy Proszynski 2001. Remarks on jumping spiders of the genus Damoetas related to Myrmarachne (Araneae: Salticidae)
 with description of two new species. Annales zoologici,  Warszawa, 51 (4): 517-522, figs 1-10. 

Traditional interpretation of relationship of Myrmarachne and similar genera was based on ant like shape of the body and possession of numerous teeth on retrolateral ventral margin of chelicerae. Additional characters were eyes I arrangement (single line along upper rim, with AME distinctly bigger than ALE), sternum elongate and thin, tibia I – not expanded laterally. That was idea expressed in Simon’s group Myrmarchneae (Simon 1901: 393, 496-503). Other interpretations concerned first of all on ant like body and resulted in merging a number of Simon’s group of genera into subfamily Myrmarachninae by Petrunkevitch 1928: 57, 182. Summing up various traditional approaches Bonnet 1959: 5052 lists 22 genera classified into Myrmarachninae, as opposed to other ant like subfamilies: Agorinae, Peckhaminae and Synagelinae. Phyletic background inferred from that approach was illustrated by Jackowska, Proszynski 1975: 40, fig 2.

Revisional study of type specimens and new material carried out by Proszynski  1976, 1984, 1987, 1991, and in press, Berry, Beatty, Proszynski  1996, Edmunds, Proszynski 2003, also complementary drawings to Philippine Myrmarachne species studied by Barrion and Litsinger 1995, available at this Internet site.

 Davies, Zabka 1989 indicated, however, other kind of similarities mutual to both Myrmarachne and other genera, not necessarily ant like. Davies, Zabka 1989: 200, dealing with Australian fauna only, considered Damoetas Peckham et Peckham, 1908, Ligonipes Karsch, 1878, Myrmarachne MacLeay, 1839 and Rhombonotus L. Koch, 1879 a part of natural group Myrmarachninae; they did not discussed non-Australian members of that group;  the present paper confirm that view.

Variation in structure in of a number of Myrmarachne species from Malaya peninsula are discussed in Edmunds, Proszynski 2003, based also on analysis of over 170 species of that genus, shown by Proszynski in the Internet monograph “Salticidae (Araneae) of the World” .The common features of Myrmarachne and several presumably related genera are palpal organ with round or oval bulbus, containing translucent internal channel of sperm reservoir - which may make either broad loop along the edges of bulbus, or, in many species, an additional small, narrow loop in the middle of bulbus. Embolus is coiled around the bulbus – usually 2 or 3 times, and expanded by white membranous or fleshy expansion along majority of its length. Tibial apophysis is surprisingly constant in many species, short, either simple or bent, often with a flange, is ended hook like. Even more striking is structure of epigynum with external membraneous "window" bisected by translucent internal longitudinal dark channel like spermathecae, which in front of the "window" form either sclerotised vesicles, or a coil, single or numerous. The entrance copulatory channel is always membranous and transparent, beginning medially and then making a complicated coil, folded and with irregular outline, ultimately joining posterior end of sclerotised vertical channels of spermathecae. It is usually overlooked, unless stained with Chlorazol Black E (whose blue staining gradually disappear during preservation in alcohol), and often damaged or removed during preparation, unless preparator is aware of its existence and particularly careful. It was observed for the first time by Proszynski 1992: 185-186, 187, figs 88, 92 and is found in every species of that group since. The vertical sclerotised channels of spermathecae have a small, porous structure just near junction with membraneous channels, slightly expanded, being possibly an opening to scent gland, whose soft duct is presumably always destroyed. The vertical sclerotised channels of spermathecae run anteriorly and in front of white membraneous “windows” ends either as slightly dilated part, or form single spherical bodies, or are bent into transversal channel. Transversal channel makes a coil, single or multiple, and then return to axial extension of original channels and ends with small swelling (always with small porous structure, being presumably nutritional pores) and is joined by soft, terminal fertilisation duct. The sclerotised terminal parts in front of “windows” have usually internal walls covered with minute teeth.

         There emerges a problem: which of these various characters, body shape, cheliceral features, or genital organs similarities are more relevant for determination of relationship among ant like Salticidae. Examination of hundreds of species, and diagnostic drawings of even more species, convinces me that above mentioned kinds of characters do change independently, in a mosaic fashion. There seem to be little correlation between cheliceral dentition, body shape, leg spination and coloration. It cannot be proved yet that genital organs similarities has more phyletic significance among species resembling Myrmarachne. But we can accept that as a working hypothesis and see to which taxonomic conclusion it can lead. 

Copyright © for the page by J. Proszynski, 2003.