Model mimics: antlike jumping spiders of the genus Myrmarachne from Sri Lanka

All nominal species of ant-mimicking jumping spiders of the genus Myrmarachne from Sri Lanka are redescribed, based on type and newly collected material. Three new species are described: Myrmarachne aurantiaca sp. nov., M. dishani sp. nov. and M. morningside sp. nov. Panachraesta Simon, 1900 is shown to be a junior synonym of Myrmarachne MacLeay, 1839, syn. nov. The following species are synonymized: Myrmarachne orientales Tikader, 1973 = Myrmarachne melanocephala MacLeay, 1839 syn. nov., Myrmarachne paivae Narayen, 1915 and Myrmarachne bengalensis Tikader, 1973 = Myrmarachne prava (Karsch, 1880) syn. nov., Myrmarachne hanoii Zabka, 1985 = Myrmarachne pumilio (Karsch, 1880) syn. nov., Myrmarachne maratha Tikader, 1973 = Myrmarachne robusta (Peckham & Peckham, 1892). One new combination is proposed: Myrmarachne paludosa (Simon, 1900) comb. nov. Myrmarachne ramunni Narayan, 1915 is recorded for the first time in Sri Lanka. A total of 12 valid species are now known from the island; six of them are endemic. http://zoobank.org/urn:lsid:zoobank.org:pub:B723C180-996B-471D-B920-4D08E7A8CD53


Introduction
The ant-mimicking genus Myrmarachne MacLeay, 1839, is one of the most speciesrich genera of Salticidae, containing over 217 nominal species naturally distributed over five continents and numerous tropical islands (Edwards and Benjamin 2009;Edwards 2013;Platnick 2013;Prószyński 2013). They are specialized ant-mimicking salticids formerly assigned to the pluridentati group (Ceccarelli 2010). Results of the most recent molecular study place Myrmarachne into a new group called the Astioida, which include pluridents, unidents and fissidents (Maddison et al. 2008). They are primarily characterized by their ant-like appearance, an issue appropriately raised by Prószyński and Deeleman-Reinchold (2010). As ant mimicry is a rather common behavioural/morphological phenomenon throughout many Arthropod taxa (Mclver and Stonedahl 1993;Cushing 1997Cushing , 2012, it alone cannot be used to define a large group of spiders (Prószyński and Deeleman-Reinchold 2010;Edwards 2013). The argument is then about the monophyly of Myrmarachne and its species groups. However, this issue could only be satisfactorily settled with the analysis of molecular phylogenetic data, independent of behaviour and morphology. salicylate (Holm 1979) and temporarily mounted as described in Grandjean (1949) and Coddington (1983) for examination and illustration under microscope.
I have placed more weight on the use of illustrations (drawings, colour photos, SEMs) to convey the unique nature of each species, instead of the traditional method of words, as I think that a single well-composed illustration can convey more information on a species. Chelicerae dentition has been traditionally used in the identification of Myrmarachne species. However, my examination of specimens of Sri Lanka species shows that dentition patterns are variable and are thus, not used in their characterization.

Remarks
The type species of Myrmarachne, M. melanocephala was redescribed and a neotype designated by Edwards and Benjamin (2009). The type species of Panachraesta is here considered a typical member of the genus Myrmarachne; see redescription of the species below. Diagnosis and description for the genus is provided by Wanless (1978), Edwards andBenjamin (2009), Prószyński andDeeleman-Reinchold (2010) and Yamasaki and Ahmad (2013).

Etymology
The specific name refers to the red colouring of the prosoma.

Diagnosis
M. aurantiaca sp. nov. could be separated from other Sri Lankan Myrmarachne species by the body size, dorsally flat surface of the male chelicerae ( Figure 1A

Description
Male holotype. Total length: 3.5; prosoma length: 1.6, width: 0.8. Leg I: femur 0.9, patella 0.3, tibia 0.9, metatarsus 0.5, tarsus 0.3. Prosoma orange, opisthosoma anteriorly brownish, posterior half, black colour ( Figure 1A, B). The cephalic part of the prosoma elevated, viewed dorsally lateral sides slightly rounded. The thoracic part is lower than the cephalic, the highest point being the centre ( Figure 1A, B). Opisthosoma oval, slightly longer than wide, with no clear constriction, except for a white line ( Figure 1); dorsum sclerotized, venter softer. Chelicerae are shorter than the carapace, with almost parallel lateral sides; distal half is a bit wider than the proximal half ( Figure 1A, B). Chelicerae dentition not examined. Leg formula 4132. Leg spination not examined. Palps as in Figure 1C, D), with an RTA which is characteristically curved at its base. Female remains unknown.

Distribution
Known only from the type locality.

Diagnosis
Very similar to M. ramunni; however, males are separated by the shape of the male chelicerae: with chelicerae in dorsal view, outer margins of chelicerae are weakly  venter softer. Chelicerae are almost the length of the carapace, lateral sides almost parallel; distal half is a bit wider than the proximal half ( Figure 2A-D). Chelicerae dentition not examined. Leg formula 4132. Leg spination not examined. Palps as in Figure 3A-D. Female remains unknown.

Distribution
Known only from Sri Lanka.

Etymology
The species is named for my wife Dishani P. Benjamin. Used as a noun in apposition.

Diagnosis
Separated from all other Sri Lankan species of the genus except for M. imbellis, by the presence of a cylindrical opisthosoma, which lacks any visible constriction. Similar to M. imbellis, but separated by the presence of white bands on the prosoma and centre of the distal half of the chelicerae (Figures 5A-C, 8G, H). The white bands are clearly visible in live as well as alcohol preserved specimens. Further, males are separated by the stout RTA with a tapering tip ( Figures 6A, B, 7C-E). Females are separated by the oval CO and relatively shorter S ( Figure 6D, C).

Description
Male: total length: 7.2-9.2; prosoma length: 4.8-6.0, width: 1.2-1.6. Leg I: femur 2.3, patella 0.8, tibia 2.0, metatarsus 1.2, tarsus 0.8. Prosoma almost 2× longer than wide. The cephalic half is somewhat elevated from the thoracic half, lateral sides parallel, with conspicuous white bands fringed with white hairs as in Figures   darker lateral sides ( Figure 8G, H). The white bands are faintly visible in preserved specimens ( Figure 8G, H). All legs are brownish with dark rings, yellowish in preserved specimens (Figures 5A-C, 8G, H). All eyes surrounded by dark rings. Chelicerae elongated, shorter than carapace, with slightly convex inner and outer sides, dorsal surface is broader than the ventral surface. They are black in colour with a prominent white band fringed with white hairs in the centre of the distal half ( Figure 5A-C). Leg formula 4132. Leg spination not examined. Palps as in Figure 6A, B. Female paratype: total length: 4.0; prosoma length: 1.8, width: 0.8. Leg 1: femur 0.8, patella 0.3, tibia 0.6, metatarsus 0.4 tarsus 0.3 Morphology as above, however, females lack the white fringes present in the chelicerae and prosoma of males. Leg formula 4132. Leg spination not examined. Epigynum and vulva as in Figure 6C, D.

Description
Male from Horton plains NP: total length: 6.8; prosoma length: 4.0, width: 1.4. Leg I: femur 1.2, patella 0.6, tibia 1.2, metatarsus 0.8, tarsus 0.4. Prosoma oval, almost as much as 2× longer than wide. The cephalic half is only slightly elevated from the thoracic half, lateral sides parallel. Opisthosoma cylindrical, almost as much as 2× longer than wide, uniformly dark brown ( Figure 8A-D). Preserved specimens are yellowish with darker lateral sides ( Figure 8A-D). All legs are brownish with dark rings, yellowish in preserved specimens. All eyes surrounded by dark rings. Chelicerae long but shorter than carapace with slightly convex inner and outer sides ( Figure 8A-D). The dorsal surface is broader than the ventral surface. Leg formula 4132. Leg spination not examined. Palps as in Figure 10A-C. Female from Horton plains NP: total length: 5.6; prosoma length: 2.8, width: 1.2. Leg 1: femur 1.2, patella 0.6, tibia 1.2, metatarsus 0.8 tarsus 0.4. Morphology as above. Leg formula 4132. Leg spination not examined. Epigynum and vulva as in Figure 11A-C. CO rounded and S relatively longer ( Figure 11A-C).

Distribution
Known only from Sri Lanka.  Opisthosoma elongated with a constriction at the posterior 25% margin, anterior 25% brown/black, posterior 75% black ( Figure 17A-D). Further, the flattened hookshaped RTA and the elongated petioles are diagnostic ( Figures 17A-D, 19A-D). Similar to M. prava. However, can be easily separated from M. prava by the overall black colour of the male, very much shorter pedicel, slanted dorsal surface of the chelicerae, oval opisthosoma, and by the tapering, straight RTA in M. prava.

Description
See Edwards and Benjamin (2009).

Distribution
Sri Lanka, India, Pakistan to Indonesia (Edwards and Benjamin 2009).

Paratype
Male from Sri Lanka, same data as holotype.

Etymology
The specific name is a noun in apposition taken from the type locality.

Diagnosis
Very similar in outward appearance to M. spissa. Separated from it by the diskshaped tegulum and shiny appearance, mostly of the dorsal parts of the prosoma.

Distribution
Endemic to Sri Lanka.

Natural history
Collected together with ants of the genus Camponotusprobably the same species collected with M. paludosa comb. nov. However, it is not the Camponotus species found with M. prava.

Diagnosis
Myrmarachne paludosa (Simon, 1900) comb. nov. could be separated from other Sri Lankan Myrmarachne species by the shape of the chelicerae: proximal half of chelicerae not constricted, outer sides more or less parallel, curved dorsum. Further, the black coloured body covered with fine white hairs ( Figures 14A-G, 15A, B) and the upward pointing, tapering RTA is diagnostic. Females may be separated by the elongated S that partly surrounds CO, connecting to it at the bottom margins ( Figure 15E-H).

Distribution
Known only from Sri Lanka. Probably endemic as it occurs only in primary forest of the wet zone and is absent in the surrounding dry forest and coastal regions.

Synonymy
Narayan's (1915: figure 8), description and illustration of M. paivae correspond well with my Figures 23A, D, 25A, C. Tikader's (1973) figure 18 illustrates an epigynum with the characteristic oval CO tipped towards the median axis and elongated S, parallel to the median axis, facilitating unambiguous identification. This species was 'lost' to science as Roewer (1954) decided to list them as unidentifiable (nicht zu deuten!). It is not mentioned in either Platnick (2013) or Prószyński (2013).

Journal of Natural History 2641
Diagnosis Separated from other Sri Lankan Myrmarachne species by the shape of the dorsal surface of the chelicerae, which slant towards the median axis. Further, the oval opisthosoma which lack any constrictions and the tapering, upward pointed RTA. Females could be separated by the oval CO tipped towards the median axis (the anterior ends are closer to the median axis than the posterior ends) and the elongated S which are parallel to the median axis.

Description
Male (from Anuradapura): total length: 8.0; prosoma length: 5.2, width: 1.4. Leg I: femur 2.0, patella 0.8, tibia 1.9, metatarsus 1.3, tarsus 0.6. Coloration as in Figures  23A-D, 25A-D. Prosoma black with evenly distributed white hair, chelicerae reddish. Opisthosoma grey with white hair. The cephalic part of the prosoma is elevated, sides somewhat curved. Prosoma constricted in the centre. The thoracic part is lower than the cephalic part, oval in shape (dorsal view) and slopes to towards the base. Opisthosoma oval, 1.5× longer than wide. Chelicerae shorter than prosoma, dorsum slants towards the median axis, lateral sides rounded ( Figure 25A-D). Chelicerae dentition not examined. Leg formula 4132. Leg spination not examined. Palps as in Figure 26A-D. Female: total length: 6.4-7.2; prosoma length: 2.8, width: 1.2. Leg 1: femur 1.6, patella 0.6, tibia 1.2, metatarsus 0.8 tarsus 0.4. Morphology as above, except for the unmodified chelicerae. Coloration as in Figures 23E, 24A-D. Leg formula 4132. Leg spination not examined. Epigynum and vulva as in Figure 27A-C. The oval CO tipped towards the median axis (the anterior ends are closer to the median axis than the posterior ends) and the elongated S which are parallel to the median axis are characteristic for this species.

Natural history
The specimens from Nikaravatiya were collected along with a species of ants of the genus Camponotus. Both the spider and its ant host are illustrated in two beautiful hand drawings by G.M. Henry (2000). Borges et al. (2007) associated the ant Camponotus compressus (Fabricius) with this species (identified as Myrmarachne morpho species 2). However, Tikader (1973) reports that Myrmarachne bengalensis was collected along with the ant Leptogenys processionalis (Jerdon, 1851), which could be a misidentification.

Distribution
India, Sri Lanka.

Type material
The type specimen was not found, presumed lost. Pickard-Cambridge (1869) says that the single specimen that he described was found in the collections of OUMNH. Type locality was unknown at the time of description.

Diagnosis
Separated from all other Sri Lankan species of the genus, except for M. spissa by the cylindrical tegulum of the male palp, with the embolus positioned on the distal end of the tegulum and the kidney-shaped S connected by a CD to CO. Separated from M. spissa by size and brown to dark brown colour.  Figure 30C, D). See Edmunds and Prószyński (2003) for a detailed description of this species.

Variation
This species is known to be highly polymorphic with colours varying from light brown to dark black (personal observations; Borges et al. 2007).

Natural history
Feeds on the ant Oecophylla smaragdina, which it mimics (Narayan 1915;Tikader 1973). The range of this species overlaps the range of its ant model (Pollard 1994;Borges et al. 2007).

Identification
Types have not been examined. Narayan (1915) illustrates and describes the unique chelicerae of this species, aiding positive identification.

Diagnosis
Very similar to M. bicurvata, however, males are easily separated by the chelicerae. The distal half of the chelicerae of M. ramunni is wider than the proximal half ( Figure 2E). The inner and outer sides of the proximal half are parallel, whereas the distal half has convex outer sides and parallel inner sides. M. bicurvata has parallel inner and outer sides (Figure 2A, C). The RTA of the male palp is broad base and tapered to a point in one corner. In M. bicurvata the RTA is hook-shaped with a constriction at the base ( Figure 3B, E).

Description
Male: total length: 6.8; prosoma length: 4.4, width: 1.2. Leg I: femur 1.6, patella 0.6, tibia 1.6, metatarsus 0.8, tarsus 0.4. The cephalic part of the prosoma is elevated and rounded on all sides. The thoracic part is lower than the cephalic, the highest point being the centre ( Figure 2E, F). Opisthosoma oval, almost as wide as long, with no clear constriction ( Figure 2E, F). Dorsally sclerotized, ventrally softer. Chelicerae are characteristically long and stout, distal half is wider than the proximal half ( Figure 2E, F). The distal half is hammer-shaped. The inner and outer sides of the proximal half are parallel, whereas the distal half has convex outer sides and parallel inner sides. Chelicerae dentition not examined. Leg formula 4132. Leg spination not examined. Palps as in Figure 3E, F. Female: remains unknown, but see Dyal (1935) for a description of a female attributed to this species.  uniformly black colour (Figures 33, 34). Further, this species could be separated from M. morningside sp. nov. by the presence of white setae mostly of the dorsal parts of the prosoma and the presence of two whitish, elongated setae approximately on the centre of the prosoma (Figures 33, 34).

Distribution
Sri Lanka.

Variation
The Monaragala District specimen is a bit larger than the specimen from Padaviya. Some recently collected specimens are darker, the light colour of the types might be due to preservation.

Natural history
Specimens from Atidiya live in association with a species of ants of the genus Technomyremex (vouchers deposited in MHNG). Specimens from Kurunagala, Nikaravatiya were collected with ants of the genus Cataulacus.

Remarks
The description of M. maratha fits the holotype of M. robusta. I thus consider the former a junior subjective synonym of the latter.