Myrmarachne (Araneae: Salticidae) in the Region F

GENERAL A revision of the spider genera Belippo and Myrmarachne (Araneae: Salticidae) in the region F. R. Wanless Department of Zoology, British Museum (Natural History), Cromwell Road, London SW7 5BD Contents Synopsis 1 Introduction 1 Methods and terminology 2 Abbreviations of depositories 3 Revision of genera 5 The genus Belippo 5 Definition 5 Diagnosis 7 Biology 7 Key to species 7 The genus Myrmarachne 18 Definition 19 Diagnosis 19 Species groups 19 Variation 20 Biology 21 Distribution in the Ethiopian region 23 Key to species 23 Species Incertae sedis 1 26 Unavailable names 1 26 Acknowledgements 126 References 135 Index . 137 Synopsis The spider genera Belippo Simon and Myrmarachne Macleay in the Ethiopian region are revised. All the 7 known species of Belippo (of which 2 are new) and 56 known species of Ethiopian Myrmarachne (of which 24 are new) are described and figured. Biological and distributional data are given and separate keys to the species are provided. In Myrmarachne certain species groups based on the structure of the genitalia are proposed. The type-material (including 60 holotypes) of 84 nominate species was examined and 23 lectotypes and 1 neotype are newly designated. One generic and 21 specific names are newly synonymized and 6 new combinations are proposed. Introduction The Salticidae is a large, well-defined cosmopolitan family of spiders with most species in the warmer regions of the world. More than 3000 species, classified in about 400 genera, have been described but a large proportion of these cannot be recognized with certainty on the basis of the existing literature. The genera of this family were grouped by Simon (1901) into three artificial sections, the Pluri- dentati, Unidentati and Fissidentati, based on the dentation on the lower margin of the chelicerae. Bull. Br. Mus. not. Hist. (Zool.) 33 (1): 1-139 Issued 23 February, 1978 Such a system of classification is unacceptable, as Proszynski (197 la) has already pointed out, but a more natural system cannot be proposed until existing genera have been revised. This paper, the first of a proposed series on the Salticidae, revises the ant-like genera Belippo and Myrmarachne in the Ethiopian region. Belippo Simon, 1910, was formally monotypic but in the present paper it has been redefined and expanded to include seven species that are all West African in distribution. Myrmarachne Macleay, 1838, contains at present 164 species. Although the genus is cosmopolitan only 9 species have been described from the New World, all from the Neotropical region (Galiano, 1969, 1974). In the Ethiopian region 58 species are now known and according to Roewer (1954) there are 12 species in the Palaearctic region, 76 species in the Oriental region and 9 species in the Australian sub-region. Provisional studies suggest that the Oriental region will prove to be far richer in species of this genus than our present knowledge indicates. Simon (1886) described the first species of Myrmarachne from Africa and six years later Peckham & Peckham (1892) described the first Madagascan species in an early review of ant-like Salticidae. In their study, all of the known ant-like salticid genera were redefined mainly on the general form of the carapace and on the size and position of the eyes; they also proposed numerous new species and several new genera including lola and Hermosa. In proposing his classification of the family Salticidae, Simon (1901) redefined Myrmarachne and made it the type of a suprageneric group, the 'Myrmarachneae'. He synonymized lola and Hermosa with 1 Myrmarachne and transferred a number of the Peckhams species which had been described in Salticus to Myrmarachne. In a supplement to his main work, Simon (1903) described a new genus Bizone for an unusual Madagascan species. After the pioneer works of Simon and the Peckhams there followed a period in which many new species were described and several important papers by Szombathy (1913, 1915), Lessert(l925a, 1925b, 1942), Berland & Millot (1941) and Lawrence (1938, 1941) did much to increase our knowledge of the species in the Ethiopian region. Myrmarachne is now one of the largest genera in the Salticidae and includes more species than any of the other ant-like salticid genera. In 1965 Roewer revised Myrmarachne in the Ethiopian region as part of his studies on the Lyssomanidae and Salticidae-Pluridentati. Roewer's work, published posthumously, is unsatisfactory, the descriptions and figures are inadequate and the key to Myrmarachne is based on unreliable characters. Of the 22 new species of Myrmarachne described by Roewer. 12 have been synonymized in this present work. Mimicry in spiders has been reviewed by Peckham (1889), Pocock (1909) and Brignoli (1966). Hingston (1927) has described behaviour in several unidentified Indian Myrmarachne. However, our knowledge of the biology of this genus is largely based on the excellent studies of Mathew (1934, 1940, 1954) on M. plataleoides (O. P.-Cambridge), from India, and Collart (1929a, 1929b, 1941) on M. foenisex Simon, from Africa. Additional observations on M. plataleoides have been made by Bhattacharya (1939) on moulting and metamorphosis, and Marson & Carpenter (1946) and Marson (1947) on behaviour. Methods and terminology Specimens were examined in a dish of alcohol, the bottom of which was covered with glass beads. The drawings, except those of the vulvae, were made with the aid of a camera lucida attached to a dissecting microscope. The epigyne and male left palp (when present) were removed for study. After drawing, the epigyne was cleared in warm lactic acid on a well slide and redrawn with the aid of a camera lucida attached to a compound microscope. It was then returned to alcohol and the genitalia stored in micro-vials. Specimens used for scanning electron microscopy were air dried and vacuum coated with gold before examination. The synonymy only includes more important citations and references of nomenclatorial sig- nificance; for complete synonymy see Bonnet (1945-61). The terminology is explained in Figs 1-3 and examples of microsculpture are shown in a series of scanning electron micrographs (Pis 1-3). The terms used to describe microsculpture are sometimes difficult to interpret as they have been used in different senses by various authors (Eady, 1968). This is not surprising as the scanning electron microscope reveals detail that is far beyond the resolution of the dissecting microscope. All the specimens examined in this study exhibit more than one form of microsculpture which may intergrade to form complex patterns or abruptly change from one type of sculpture into another. Fine reticulate forms of sculpture, which often occur on the thoracic part, cannot always be resolved with the dissecting microscope and it is often difficult to decide which form of sculpturing is present, particularly as lighting effects can cause an apparent reversal of reticulate and papillate structure. A similar effect can even be illustrated by viewing PI. Ih upside down. The most common patterns that can normally be seen with the dissecting microscope are punctured-reticulate (PI. la, b), especially within the eye region, and rugulose with irregular cross furrows (PI. Ic, d) on the dorsal surface of the chelicerae. Other widespread but less conspicuous patterns are alutaceous on the abdomen (PI. Ig) and raised reticulate on the sternum (PI. le, f). Papillae (PI. 3c, d) are probably more widespread than I have indicated in the descriptions as they may have been overlooked; the thoracic papillae of Myrmarachne marshalli Peckham & Peckham and M. legon sp. n. were not noticed until specimens were examined with the stereoscan microscope. Rippling (PI. 2d), smooth and irregular punctures (PI. 2b) are fairly rare but sometimes clear enough to be used as a diagnostic character. The measurements, which are accurate to 0-05 mm, were made with an eyepiece micrometer and the system used is explained in Figs 1-2. There is no point in always giving absolute measurements (e.g. in mm) as their principal value is in their relation to the measurements of other parts. Eye size is expressed in ratios made from the type-specimen but variation is not given. Four standard abbreviations, AM, AL, PM, PL, refer respectively to the anterior median, anterior lateral, posterior median and posterior lateral eyes. Eye interdistances are denoted by dashes, i.e. PM-PL refers to the distance between the posterior median and posterior lateral eyes. Eye ratios refer to the diameter of the lens and not the encircling pigment which is normally present. From the measurements several indices are derived: a: width of eye row I/carapace width at that point; decreasing values below 1-0 indicate a space between the anterior lateral eyes and the sides of the carapace at that point, b: width of eye row Ill/carapace width at that point; increasing values above 1-0 indicate that the posterior lateral eyes project over the sides of the carapace at that point. c: quadrangle length/carapace length; a value of 0-50 indicates that the eye region and thoracic part are of equal length, d: chelicerae length (males only)/carapace length; increasing values above 1-0 indicate that the chelicerae are longer than the carapace, e: tibia plus patella IV/carapace length; decreasing values below 1-0 indicate that the tibia plus patella IV are shorter than the carapace. The indices a, b and d exhibit a greater range of variation in males and are good indicators of allometric growth. Ratio c is less variable but it is sometimes used as a diagnostic character. Ratio e is the most useful index to be derived from measuring the leg segments of type-specimens, it is rather variable but can be useful for separating closely related females. All indices can be derived from whole specimens and dissection is not necessary.

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