The genus Myrmarachne (Araneae, Salticidae) in Flores, Indonesia

Abstract Two new species of the genus Myrmarachne are described (Myrmarachne acutidens sp. n., Myrmarachne epigealis sp. n.), and Myrmarachne macrognatha and Myrmarachne melanocephala are redescribed from Flores specimens. The females of Myrmarachne macrognatha are recorded for the first time.


Introduction
The genus Myrmarachne MacLeay, 1839 is one of the largest groups in the family Salticidae, including around 250 species (Prószyński 2012;Platnick 2012). The members of the genus generally resemble ants morphologically and behaviorally, and the resemblance is considered to be due to Batesian mimicry (Wanless 1978). The area from Southeast Asia to Australia through the Malay Archipelago harbors many Myrmarachne species. Wallacea, the non-continental transition zone between the Oriental (Sundan) and Australian (Sahulian) zoogeographical regions, is bounded to the west by paper are as follows: AME, anterior median eye; ALE, anterior lateral eye; PME, posterior median eye; PLE, posterior lateral eye; pd, prodorsal; pv, proventral; rd, retrodorsal; RTA, retrolateral tibial apophysis of palp; rv, retroventral.
Male (Figs 2-9). Cephalic part almost flat dorsally, distinctly higher than thoracic part; lateral surface of carapace strongly incised behind PLE; dorsum of thoracic part weakly convex in middle part, and then sloping downward (Figs 2-3). Chelicera almost as long as carapace, its anterior part weakly swollen dorsally and wider than posterior part; venter of chelicera bearing seven to ten prolateral and two to four retrolat- eral teeth; apical two prolateral and one retrolateral teeth large, especially second prolateral tooth counted from apex very long (Fig. 5). Fang weakly sinuous, bearing short tooth-like apophysis on venter near its middle, and weak protuberance on dorsum of its base (Fig. 6); proximal part of fang strongly arched. Pedicel short (0.25-0.32 mm). Abdomen oval without distinct constriction, and with two contiguous dorsal scuta; each lateral margin of where scuta are contiguous strongly incised at anterior third.
With palp in dorsal and ventral views, cymbium elongate-oval, with one apical spine (Fig. 8). Tegulum oval, with ejaculatory duct along proximal and prolateral margins, and rounded V-shaped ejaculatory duct at distal retrolateral margin of tegulum (Fig. 8). Embolus forming two oval coils; embolus coils occupying more than half of venter of cymbium, and basal coil as wide as venter of cymbium, while more ventral coil is slightly smaller (Fig. 8). With palp in dorsal and ventral views, RTA curved outward, with well-developed its flange; with palp in retrolateral view, RTA strongly s-curved with tip slightly spiraled (Figs 7,9).
Coloration in alcohol and pilosity. Carapace covered with white setae; cephalic part black and thoracic part dark brown; lateral surface of carapace above coxae I and II densely fringed with white setae (Figs 2-3). Chelicera dark brown; boundary between anterior swollen part and posterior narrow part fringed with white setae; anterior swol- len part covered with long setae. Endite brownish cream. Labium and sternum dark brown (Fig. 4). Coxa and trochanter I dark yellow suffused with gray, coalesced into lateral dark stripe; coxae II and III black, distal prolateral part of coxa II yellowish suffused with gray, trochanter II like trochanter I except lighter yellow, trochanter III with more extensive lateral stripe and yellowish venter suffused with gray; coxa IV dark yellow with gray lateral stripes, trochanter IV white with short lateral gray marks (Fig.  4). Abdomen and its dorsal scuta black, covered with fine setae (Figs 2-3).
Female . With carapace in lateral view, cephalic part roundly convex dorsally, slightly higher than thoracic part; dorsal concavity behind PLE distinct; dorsum of thoracic part roundly convex overall (15)(16). Chelicera bearing four to six prolateral and seven to eight retrolateral teeth on its venter. Pedicel usually short, but sometimes long (0.23-0.95 mm). Abdomen oval, without distinct constriction (15)(16). [18][19]. Copulatory atria containing openings round. Median copulatory structure in front of epigastric furrow divided into lateral pockets; each lateral margin anteroposteriorly flattened. Sclerotized copulatory ducts emerging from oval spermathecae with complex twists, then extending between atria to vicinity of lateral pockets.
Coloration in alcohol and pilosity. Carapace black; cephalic part covered with fine setae; thoracic part sparsely covered with white setae; lateral surface of carapace above coxae I and II densely fringed with white setae (15)(16). Chelicera light brown. Endite brownish yellow, tinged with gray (Figs 12,17). Labium cream, tinged with black (Figs 12,17). Sternum black (Figs 12,17). Coxae and trochanters similar to male pattern but lighter in color; coxae and trochanters I and II white, coxa II with variable black retrolateral stripe; coxa and trochanter III black, trochanter lighter ventrally suffused with black; coxa IV yellow with extensive lateral black stripe, trochanter IV white (Figs 12,17). Abdomen black, covered with fine setae; some white setae roughly forming transverse white band in anterior dorsum of abdomen (15)(16).
Etymology. The specific name is derived from the second prolateral tooth counted from the apex in males.
Biology. The species is arboreal, and collected from trees in secondary forests or plantation areas.
Distribution. Flores. Male . Cephalic part weakly convex dorsally, distinctly higher than thoracic part; in lateral view, dorsum of carapace sloping downward behind PLE, and concave between cephalic and thoracic parts; lateral surface between cephalic and thoracic parts weakly incised; thoracic part roundly swollen overall (Figs 20 -21). Chelicera slightly shorter than carapace; with chelicera in dorsal view, its dorsal prolateral margin diverted toward retrolateral margin in distal half, exposing prolateral surface (Fig. 20); venter of chelicera bearing four to five prolateral and eleven to 14 retrolateral teeth (Fig. 23); apical prolateral corner of venter forming large tooth-like apophysis; with chelicera in ventral view, one retrolateral tooth present next to third retrolateral tooth counted from base, and one prolateral tooth slightly proximal to row of retrolateral teeth. Fang weakly sinuous, without tooth-like apophysis (Fig. 24). Pedicel short (0.30-0.43 mm). Abdomen oval with weak constriction at anterior fourth, and its entire dorsum covered with two contiguous dorsal scuta; lateral margins strongly incised where scuta come together .

Myrmarachne epigealis
With palp in dorsal and ventral views, cymbium elongate-oval with one apical spine (Fig. 25). Tegulum oval, with long seminal reservoir along margin of tegulum (Fig. 25). Embolus forming two oval coils; more ventral embolus coil as wide as venter of cymbium, slightly narrower than basal coil (Fig. 25). RTA well developed with the tip curved inward, and without a distinct its flange (Figs 26-27).
Coloration in alcohol and pilosity. Carapace and chelicera black, covered with very short inconspicuous setae (Figs 20 -21). Carapace with pair of light brown spots behind PLE. Endite, labium and sternum light brown, tinged with black (Fig. 22). In ventral view, coxa and trochanter I light yellow, tinged with gray on posterior margin of coxa and laterally on trochanter; coxa II black, trochanter II like trochanter I; coxa and trochanter III black, trochanter yellow ventrally strongly tinged with black; coxa IV blackish with yellow venter strongly tinged with black, trochanter IV light yellow (Fig. 22). Abdomen and its dorsal scuta black, covered with fine setae (Figs 20 -21).
Coloration in alcohol and pilosity. Carapace mainly black, covered with white setae densely; carapace with pair of light brown spots behind PLE; lateral surface of carapace above coxa I white, densely fringed with white setae (Figs 28-29). Chelicera brown. Endite, labium and sternum brownish cream, weakly tinged with black (Fig.  30). Coxae and trochanters in ventral view similar to those of males, except coxa IV with much more yellow ventrally, and trochanter IV yellow with distal retrolateral black spot (Fig. 30). Abdomen covered with golden setae dorsally, and with fine setae ventrally (Fig. 28).
Etymology. The specific name is derived from the ground microhabitat, where the species often occurs.

Myrmarachne macrognatha
Male . With carapace in lateral view, cephalic part almost flat dorsally, higher than thoracic part; dorsal concavity behind PLE shallow or indistinct; thoracic part sloping downward, not distinctly convex dorsally (Figs 33-34). Chelicera distinctly longer than carapace, each lateral margin almost parallel-sided except for distinctly convex prolateral margin near anterior end of chelicera; venter of chelicera bearing nine to twelve prolateral and three to six retrolateral teeth; fourth prolateral tooth counted from apex long and strongly curved (Fig. 36). Fang almost straight or very weakly sinuous except for curved tip and base, with long tooth-like apophysis on its venter at about 1/4 the length of fang from its base (Fig. 37). Pedicel short (0.18-0.30 mm). Abdomen oval without distinct constriction, with dorsal two scuta that are clearly separated.
With palp in dorsal and ventral views, cymbium elongate-oval, with one apical spine (Fig. 38). Tegulum round and small, with s-curved ejaculation duct in distal retrolateral part of tegulum (Fig. 38). Embolus forming two round coils; embolus coils occupying less than half of venter of cymbium; ventral coil much smaller than basal coil, only about half the diameter (Fig. 38). RTA strongly curved, and in retrolateral view, somewhat spiraled (Fig 38-40). Flange of RTA moderately developed.
Coloration in alcohol and pilosity. Carapace black; cephalic part covered with fine white setae, and thoracic part sparsely covered with white setae; lateral carapace not fringed with white setae (Figs 33-34). Chelicera dark brown to black, and long white setae roughly forming transverse band in anterior part of chelicera. Endite and labium brownish orange, tinged with black laterally (Fig. 35). Coxae and trochanters I, III, IV yellow with gray lateral stripes; coxa and trochanter II cream-white, coxa with gray lateral stripes; in large specimens, coxae sometimes strongly tinged with black ( Fig.  35). Abdomen and its dorsal scuta black, covered with white long setae and fine setae dorsally (Figs 33-34).
Female . With carapace in lateral view, cephalic part weakly convex dorsally, slightly higher than thoracic part; dorsal concavity behind PLE distinct; thoracic part swollen dorsally (Figs 41-42). Chelicera bearing five to six prolateral and six retrolateral teeth on its venter. Pedicel relatively longer than that of males (0.35-0.43 mm). Abdomen oval, without distinct constriction and dorsal scutum. . Copulatory atria containing openings oval. Lateral pockets present in front of epigastric furrow, anteroposteriorlly flattened. Sclerotized copulatory ducts clearly twisted in "figure 8" adjacent to cylindal spermathecae, then extending between atria to approximately the area of the lateral pockets.
Coloration in alcohol and pilosity. Carapace dark brown to black; cephalic part covered with white and fine setae; thoracic part covered with white setae; lateral surface of carapace above coxae I and II densely fringed with white setae; white setae roughly forming white diagonal band from above coxa IV to upper dorsum (Figs 41-42). Chelicera dark brown. Endite, labium and sternum brownish orange, weakly tinged with black. Coxae and trochanters I and II white; coxa and trochanter III black, trochanter with yellow venter; coxa and trochanter IV pale yellow with lateral gray stripes (Fig. 43). Abdomen gray, covered with fine setae; two spots behind two white partial transverse bands present dorsally in anterior part of abdomen (Figs 41-42). Remarks. The specimens from Flores are slightly different from the holotype of M. macrognatha from Java in the cheliceral teeth. The third prolateral tooth counted from the apex of the Flores specimens is shorter than that of the holotype (which has both the third and fourth teeth elongate). Although the number and size of cheliceral teeth is variable, generally corresponding to body size, the short apical third prolateral tooth seems to be a stable character within our specimens collected from Flores regardless of body size. However, we regard the Flores specimens as M. macrognatha on the basis of many other morphological similarities. To understand geographical variation of the species, a phylogenetic study based on molecular analysis is needed in the future.
Biology. Myrmarachne macrognatha is an arboreal species, and very common and abundant in eastern Flores.
Distribution. Java, Flores. Diagnosis. Slender, light to dark brown species with relatively long pedicel. Males distinguished from other species by pedicel, which is as long as ALE-PLE (Fig. 46); further distinguished from species having long pedicel such as M. assimilis Banks, 1930(cf. Figs 7, 13 in Banks 1930, M. cornuta Badcock, 1918 (cf. Figs 30-35 in Edmunds andPrószyński 2003) and M. plataleoides (O. Pickard-Cambridge, 1869) (cf. Figs 1-7 in Edmunds and Prószyński 2003) by shape and dentition of chelicera (Fig. 49). Females distinguished from others species by long pedicel as in males (Fig. 54)   The male specimen examined in the present study has relatively short chelicera compared with specimens from other areas. The male chelicera varies in the length depending on the body size within a species. The female specimens examined here agree with the description of M. melanocephala and specimens from other areas, in particular the gray abdomen with transverse median black band is typical of popula-tions throughout Southeast Asia, but lighter in color than the mostly black topotypical specimens from India. This seems to be only regional color variation.

Myrmarachne melanocephala
Biology. The specimens were collected from plantation areas. Distribution. Widely distributed in South and Southeast Asia.