Myrmarachne smaragdina, Ceccarelli, F. Sara, 2010

Ceccarelli, F. Sara, 2010, New species of ant-mimicking jumping spiders of the genus Myrmarachne MacLeay, 1839 (Araneae: Salticidae) from north Queensland, Australia, Australian Journal of Entomology 49, pp. 245-255 : 250-253

Myrmarachne smaragdina sp. nov. Figures 28–36

Etymology. Named after its model ant, Oecophylla smaragdina (Fabricius, 1775) ( Formicidae : Formicinae ), the name smaragdina deriving from the adjective denoting the green colour of the gaster.

Material examined. Holotype: QM S66653 (male, collected by FS Ceccarelli on Magnetic Island , 19°09′11″S, 146°50′52″E, 28 August 2003) . Allotype: QM S66652 (female, collected by FS Ceccarelli on Magnetic Island , 19°09′11″S, 146°50′52″E, 28 August 2003) . Paratypes: QM S403 (male, collected by GB Monteith by the McIver river, 40 miles north of Cooktown , 7 May 1970) ; QM S73295 (female, collected by BM Baehr 3 km north of Mudjinberri , 4 November 1984) ; AM KS18304 (female collected by R Mascord in Edmonton , 2 September 1976) ; AM KS19169 (two females collected by D Levitt in Angurugu via Darwin , Northern Territory, 28 May 1969) ; AM KS44998 (male, collected by D Citin at Berrimah research station , 24 March 1988) ; AM KS44999 (male, collected by D Citin at Berrimah research station , 24 March 1988) ; AM KS5771 (female, collected by R Mascord in Edmonton , 27 August 1970) ; AM KS93122 (male, collected by FS Ceccarelli in Townsville , 4 January 2006) .

Diagnosis. Male chelicerae about the same length as the carapace, containing 18 retromarginal teeth, and a fang apophysis. The tibial apophysis of the male palp is black and hooked, and the flange is not developed. The diameter of the tegulum is approximately one-third of the length of the cymbium; the distal end of the cymbium contains one major seta. The female epygine contains looped spermathecae (into a figureof-eight) and lateral pouches. M. smaragdina can be differentiated from M. lupata by the relative length of the male chelicerae, by the orientation of the embolus and by the spination of the first pair of legs. The chelicerae of male M. lupata are described as being longer than the carapace by a quarter of its length, whereas the chelicerae of M. smaragdina are about the same length as the carapace. In the male palps of M. lupata , the embolus points straight towards the tip of the cymbium, whereas the depression in the cymbium of M. smaragdina forces the embolus to lie at a 45° angle relative to the longitudinal line of the cymbium. Finally, M. lupata has no spines on its first pair of legs, whereas M. smaragdina has two pairs of spines on the metatarsus, and four pairs on the tibia of legs I.

Description. Male: Carapace: orange/light brown with black pigmentation around the eyes; sparsely covered with white hairs; wedge-shaped constriction in the middle of the carapace. Eyes: procurved AMs, fringed with hairs and black pigment. Clypeus: fringed with white hairs. Chelicerae: protruding, orange/light brown with black pigmentation ant the distal end; fang apophysis present, retromarginal dentition: 18 teeth (3 large and 15 small ones). Maxillae and labium: maxillae cream with brown margins. Sternum: yellow and orange. Opisthosoma: green with sparse white hairs, constriction in the middle fringed with more white hairs. Legs: slender. Legs I: tarsus white; metatarsus white; tibia light orange; patella light orange; femur light orange; trochanter white; coxa orange/ light brown. Legs II: tarsus white; metatarsus white; tibia light orange; patella light orange; femur cream; trochanter white; coxa orange/light brown. Legs III: tarsus white; metatarsus white; tibia light orange; patella light orange; femur light orange; trochanter white; coxa orange/light brown. Legs IV: tarsus white; metatarsus white; tibia light orange; patella light orange; femur light brown; trochanter white; coxa orange/light brown. Legs I spination: metatarsus 2-2, tibia 2-2-2-2, patella 0. Palp: tibial apophysis black, with a backward-curved distal hook; flange not very developed; cymbium and proximal depression fringed with setae, with one large seta at the distal end of the cymbium; embolus coiled 1 1 /2 times around bulbous tegulum of approximately 100 μm in diameter (about onethird of the length of the cymbium); seminal reservoir not very large. Dimensions: total length: 4.0– 6.2 mm; carapace length: 2.7–3.1 mm; ratio of carapace-to-chelicera length: 0.75–1.2; Ratios AME: ALE: PME: PLE: 3.29:1.13:1:1.62. Female: Carapace: same as ♂. Eyes: same as ♂. Clypeus: same as ♂. Chelicerae: non-protruding, light brown. Maxillae and labium: same as ♂. Sternum: same as ♂. Opisthosoma: same as ♂. Legs: slender, same as ♂. Legs I spination: same as ♂. Epigyne: white and orange/brown; lateral pouches separate, spermathecae simple, in a figureof-eight configuration. Dimensions: total length: 5.5–6.0 mm; carapace length: 2.6– 2.9 mm; Ratios AME: ALE: PME: PLE: 3.31:1.10:1:1.59. Distribution. Specimens recorded from Queensland, Australia: Cooktown (15°30′S, 145°16′E), Townsville (19°13′S, 146°48′E) and Edmonton (17°02′S, 145°46′E); Northern Territory, Australia: Angurugu (14°00′S, 136°25′E), Berrimah research station (12°45′S, 130°95′E) and Mudjinberri (12°05′S, 132°88′E); other areas of distribution unknown.

Remarks. Myrmarachne smaragdina belongs to the tristis group, mimics the green tree ant Oecophylla smaragdina (Formicinae) , and can be found in close association to model ant colonies. A previous study (where M. smaragdina is referred to as Myrmarachne sp. F) has shown that this species can distinguish between ants and other ant-mimics (Ceccarelli 2009). As with their model ants M. smaragdina typically occurs on trees in the proximity of creeks, with no apparent preference for the type of tree they live on. The retreats are usually built on the upper surface of leaves, the males building sheet-like retreats, and the females building woolly-looking ones, often with ‘anchoring’ threads of silk, joining the retreat and the leaf. Retreats have been found on the outside of O. smaragdina nests themselves, although this is a rare occurrence. M. smaragdina have also been found in leaf-litter, but this is presumably because the leaves on which the retreats were built fell from the tree. The females lay between 15 and 20 eggs, and the spiderlings have a brown carapace and a black opisthosoma during the first two instar stages after leaving the egg sac, bearing a close resemblance to ants of the genus Crematogaster . The last instar before adulthood looks like the smaller workers from O. smaragdina colonies, with the same colour patterns, except for more white pigmentation on the opisthosoma.