Myrmarachne MacLeay, 1839

Edwards, G. B. & Benjamin, Suresh P., 2009, A first look at the phylogeny of the Myrmarachninae, with rediscovery and redescription of the type species of Myrmarachne (Araneae: Salticidae), Zootaxa 2309 (1), pp. 1-29 : 5-10

Genus Myrmarachne MacLeay, 1839

Type species: Myrmarachne melanocephala MacLeay, 1839

( Figs 1A–H , 2A–D , 3A–D , 4A–E , 5A–D , 6 )

Myrmarachne melanocephala MacLeay, 1839: 11 , fig. 4 (Dm).

Salticus contractus Karsch, 1880: 396 (Dm) . New synonymy.

Salticus providens Peckham and Peckham, 1892: 34 (Dmf) ; New synonymy.

Myrmarachne providens Simon, 1901: 500 ; Pocock, 1908: 259; Narayen, 1915: 399.

Myrmarachne ramosa Badcock, 1918: 303 , fig. 8 (Dm); Edmunds and Prószyṅski, 2003: 301–304, figs 8–29. New synonymy.

Myrmarachne albicrurata Badcock, 1918: 306 , fig. 9a (D imm. f). New synonymy. Synonymized by Edmunds and Prószyṅski (2003) with M. ramosa .

Myrmarachne lateralis Badcock, 1918: 310 , fig. 9b (Df). New synonymy. Synonymized by Edmunds and Prószyṅski (2003) with M. ramosa .

Myrmarachne contracta Sherriffs, 1931: 539 .

Type material: Holotype of M. melanocephala : male from “Bengal” (modern day India: West Bengal State plus Bangladesh) (originally kept in MacLeay collection: apparently lost). As this species was described only from the holotype and is the type species of the genus, it is necessary to designate a neotype to clarify the taxonomic status of the species. Conditions satisfying ICZN Article 75.3 are given below and in the Acknowledgments.

Neotype of M. melanocephala (herewith designated): INDIA: West Bengal: Calcutta, Calcutta Botanical gardens, 22° 34' N, 88° 24' E, 25 July 1973, leg. Ginter Ekis ( USNM 2049842 ), examined. According to ICZN Article 76.3, the locality of the neotype becomes the type locality.

Syntypes of Salticus contractus : one male from Ceylon (now Sri Lanka), leg. Hoffmann ( ZMB 1538 ), no more data given, examined, herewith designated as the lectotype ( Figs 1D – F , 4D ); and one badly damaged male from Bintang Island , Indonesia, leg. Böttger ( ZMB 1537 ), no more data given, examined, herewith becoming the paralectotype ( Figs 1G – H ) .

Syntypes of Salticus providens : one male and one female from Ceylon, leg. E. Simon ( MCZ 22768), no more data given, examined ( Figs 1A – C , 4A – C , 5A ) .

Holotype of Myrmarachne ramosa : male, from “Malay States,” leg. N. Annandale and H. C. Robinson, 1901–1902, no more data given, examined.

Other material examined. SRI LANKA: Ratnapura district: 1 male, Gilimale, Induruwa Jungle , 13 – 15 March 1979, leg. K. V . Krombein, T . Wijesinghe, S. Siriwardana, L. Jayawickrama ( USNM) . Colombo district: 1 male, Labugame , 25 May 1975, leg. D. H. Messersmith, G. I. Williams, P. B. Karunaratne ( USNM) . Anuradapura district : 1male 1juv, Padaviya, 19 May 1976, leg. “K. V. K.” (Krombein?) ( USNM) . Ampara district: 1 female, Ekgal Aru Sanctuary Jungle , 9 – 11 March 1979, leg. K. V . Krombein, T . Wijesinghe, S. Siriwardana, L. Jayawickrama ( USNM) . Kandy district : 1 female, Udawattakelle sanctuary, 510 – 580m, 26 – 30 July 1978, leg. K. V . Krombein ( USNM). North Western Province: 1 male 1 female, Kurunagala district, Kurunagala, Ethagala Mountains , ca. 300m, 11 October 2008, leg. Ziyard Jaleel ( MHNG) . INDIA: Uttar Pradesh: 1 male, 1 female, 2 juveniles, 1 ant ( Tetraponera rufonigra ), 5 miles SW Dehra Don , 600m, 9 November 1961, leg. E. S. Ross and D. Q. Cavagnaro ( CAS) .

Diagnosis. Other Indian and Sri Lankan Myrmarachne generally do not resemble M. melanocephala in appearance (see Remarks below). Only M. prava ( Karsch, 1880) , described in the same publication as M. melanocephala (sub M. contracta ) could be confused with M. melanocephala , as both species have black females. However, M. prava can be easily separated by the overall black color of the male, very much shorter pedicel, slanted dorsal surface of the chelicerae, oval opisthosoma, and by the tapering, straight RTA, quite different from the male of M. melanocephala (from which this species was described).

Description. Male: Total length: 7.2 (7.7) 12.4; prosoma length: 4.0 (4.1) 6.4, width: 1.2 (1.3) 1.6. Leg I: femur 1.6, patella 0.8, tibia 1.6, metatarsus 0.8, tarsus 0.4. Prosoma elongated with a constriction at the 50% point, anterior half black, posterior half red/brown. Opisthosoma elongated with a constriction at the anterior 25% margin, anterior 25% red/brown, posterior 75% black ( Figs 2A – D , 3A ). All legs red/brown with black and white rings. Chelicerae enlarged, brown/black, dorsally flattened, median margin parallel. Teeth: neotype with 13 longer teeth on outer margin distributed full length of chelicera, 9 tiny teeth on inner margin not distributed to either end of chelicera, spacing of teeth more sparse in middle and rows closer together from middle to proximal end, both rows sinuate, spacing of teeth not quite symmetrical between two chelicerae; other specimens similar, some with a few more teeth in same general pattern. Leg formula 4132. Leg I spination: 5 pair on venter of tibia, 2 pair on venter of metatarsi. Palps as in Figs 4A – E . Cymbium oval, as long as the palpal tibia. RTA a hook-shaped flattened spiral (although it is somewhat less flattened in the Malaysian specimens), mostly covered by the base of the cymbium, with its tip projecting outwards. Tegulum rounded and small, with sperm duct showing on ventral surface with a half loop immediately after the sperm reservoir. Embolus begins in distal retrolateral region right after sperm duct half loop, broad and appressed around proximal side of tegulum, then tapering and becoming free of tegulum on prolateral side, making a more ventral smaller spiral inside the diameter of the basal revolution, altogether forming about two spiral revolutions around the tegulum.

Female: Total length: 7.4 – 7.6; prosoma length: 3.1 – 3.2, width: 1.2. Leg I: femur 1.2, patella 0.8, tibia 1.2, metatarsus 0.8, tarsus 0.4. Females lack red/brown patches and appear darker, shape as in male except for the compact vertical chelicerae ( Figs 4B, D ). Leg formula 4132. Leg I spination as in male. Epigyne and vulva as in Figs 5A – D . CO large, two laterally-oriented pockets between CO and epigastric furrow. Each CO leads to an inverted “C” shaped duct that lead to an oval spermatheca.

Variation. Color of chelicerae and fang are variable; some fangs are black, others red/brown. Some specimens are a bit darker than others. Juvenile females lack the red/brown pigmentation and are thus black.

Distribution. Pakistan to Indonesia. Narayen (1915) reported the record from Pakistan. There are no recent records to confirm this; however, the record from India below is in the northwest part of the country, so a record from Pakistan does not seem unlikely. The natural distribution of the model ant Tetraponera rufonigra (Jerdon) is Pakistan to Java ( Ward 2001), completely overlapping the reported distribution of its spider mimic.

Natural History. As observed by Pocock (1908: 259), M. melanocephala is associated with the ant Tetraponera [reported as Sima ] rufonigra . He states, "In the Oriental Region there is a common red-and-black tree-ant, Sima rufo-nigra . It is pugnacious and fearless… On human beings the effects of its bite are both painful and lasting. Wherever these insects occur in any numbers, a species of spider [ Myrmarachne providens ], one of the Salticidae , is to be found running about amongst them. The spider closely resembles the ant in form and colour. It appears to be on the most friendly footing with its formidable associates, moving quickly here and there in their company and copying their busy, hurried actions." Further confirmation for this relationship is provided by one of the records listed above. Pocock’s comments indicate that M. providens , described from Sri Lanka (formerly Ceylon), and here shown to be a synonym of M. melanocephala , was considered a widespread species more than a century ago.

Remarks. The male of M. contracta from Bintang Island is so badly damaged that illustrating its genitalia was not attempted. Its general outline matched other examined M. melanocephala specimens (as in Figs 1G – H ; chelicerae dorsally flattened, prosoma constricted at the centre).

A species recently redescribed from Peninsular Malaysia and Singapore, strikingly similar to M. melanocephala , is M. ramosa Badcock, 1918 ( Edmunds and Prószyṅski 2003; Platnick 2009). The type of M. ramosa has been compared with the neotype of M. melanocephala (by GBE) and found to be a junior synonym, therefore the type species has been recently well illustrated. Bintang Island is very close to Singapore, and represents the southeastern most record for this species. We agree with the synonyms M. albicrurata and M. lateralis for M. ramosa as proposed by Edmunds and Prószyṅski (2003), which become synonyms of M. melanocephala .

Although many species of Myrmarachne have distinctive body shapes, final determination to species, like in most other entelegyne spiders, generally depends on the structure of the genital organs, especially when body shapes and color patterns among related species are similar. On the other hand, many well known species are easily recognized by their overall habitus, and we are of the opinion that this is true for M. melanocephala as well. It is instructive to note that Wanless (1978a: 21) clearly states, “…in Myrmarachne …the structure of the genitalia cannot always be relied upon to separate the species.” Comparison of the color plate ( Fig. 6 ) of M. melanocephala in the original description ( MacLeay, 1839) with M. contracta Karsch, 1880 , from Sri Lanka, part of a study of Sri Lankan Myrmarachne currently in progress (SPB, in prep.) showed virtually no difference in the habitus of the two species. We believe they are conspecific and that the problem of the type species of Myrmarachne has been resolved. A neotype for M. melanocephala is designated above from Calcutta, West Bengal State, India, the only specimen presently known in collections that is from the area where the original specimen was described. In the same study of the Myrmarachne of Sri Lanka, SPB has found 11 species of Myrmarachne , seven of which are described (four of these are shared with India), plus four undescribed species. India has an additional 16 described species (not counting overlapped species with Sri Lanka; Prószyṅski 2009). No other species of similar color, or somatic or genital morphology, is present in Sri Lanka. This is also true for species known from India (the fauna of which, however, is less well known than the Sri Lankan Myrmarachne fauna, as at this time, data on undescribed species from India is incomplete, although SPB notes that no undescribed Indian species he is familiar with are similar in appearance to M. melanocephala ). Therefore, we are reasonably certain that we have correctly identified M. melanocephala from among the species known from Sri Lanka and the Indian subcontinent.

Figures

FIGURE 1. Myrmarachne melanocephala. A–C M. providens syntypes from MCZ 22768; D–F M. contracta lectotype from ZMB 1538; G–H M. contracta paralectotype from ZMB 1537 (A dorsal view of male, B lateral view of male, C dorsal view of female, D male prosoma dorsal view, E male prosoma lateral view, F male opisthosoma dorsal view, G male prosoma lateral view, H male prosoma dorsal view; A–F from Sri Lanka, G–H from Bintang Island, Indonesia.)

FIGURE 2. Photographs of Myrmarachne melanocephala male from Kurunagala, Sri Lanka. A, C, D dorsal view, B lateral view.

FIGURE 3. Photographs of Myrmarachne melanocephala from Kurunagala, Sri Lanka. A male; B–D female (A, B dorsal view, C, D lateral view).

FIGURE 4. Myrmarachne melanocephala male palp. A–C MCZ 22768; D ZMB 1538; E Padaviya, Sri Lanka (A ventral view, B dorsal view, C–E retrolateral views). Scale bars = 0.2 mm.

FIGURE 5. Myrmarachne melanocephala. A MCZ 22768; B–D Ekgal Aru Sanctuary (A, B epigyne ventral view, C vulva ventral view cleared, D vulva dorsal view). Scale bars = 0.2 mm.

FIGURE 6. Myrmarachne melanocephala, replica of original plate (MacLeay, 1839).