Myrmarachne maxillosa (C. L. Koch, 1846)

Yamasaki, Takeshi & Ahmad, Abdul Hamid, 2013, Taxonomic study of the genus Myrmarachne of Borneo (Araneae: Salticidae), Zootaxa 3710 (6), pp. 501-556 : 538-541

Myrmarachne maxillosa (C. L. Koch, 1846)

( Figs 30 A–G, 31A–E, 42A–F)

Toxeus maxillosus C. L. Koch, 1846: 19 , Fig. 1090; Thorell, 1895: 328. Synemosyna procera Thorell, 1877: 538 .

Toxeus procerus Thorell, 1887: 346 .

Salticus modestus Thorell, 1892: 235 .

Myrmarachne maxillosa: Simon, 1901: 498 ; Simon, 1905: 70; Szombathy, 1913: 31, 56, Fig. 8 ; Badcock, 1918: 287, Fig. 4 . Myrmarachne gigantea Żabka, 1985: 244 , Figs 318–322, syn. nov. (cf. under Remarks)

Type material examined. Holotype male of M. gigantea (MIZ 217157), Thanh Ha, Hoa Binh prov., VIETNAM, 14 VI 1966, R. Bielawski & B. Pisarski leg.; 1 paratype male of M. gigantea (MIZ 217158), Cuc Phung, Ninh Binh prov., VIETNAM, 9 VI 1966, R. Bielawski & B. Pisarski leg.

Non-type material examined. BORNEO: 1 female, Danum Valley, Sabah, 11 IX 2005, T. Tachi leg.; 2 males, UMS, Sabah, 12–20 III 2008, H. Takizawa leg.; 2 males and 1 female, same loc., 21 III 2008, T. Yamasaki leg.; 2 males and 1 juvenile (cohabitation), Monggis substation, Kinabalu Park, Sabah, 2–4 X 2009, T. Yamasaki leg.; 1 male, UMS, Sabah, 10 X 2009, T. Yamasaki leg.; 3 males, 6 females and 1 juvenile, Mahua, Sabah, 13–14 X 2009, T. Yamasaki leg.; 1 female, Poring Hot Spring, Kinabalu Park, Sabah, 10 XI 2009, T. Yamasaki leg.; 2 juveniles, UMS, Sabah, 6 X 2010, T. Yamasaki leg.; 2 males and 1 female, Inobong substation, Crocker Range Park, Sabah, 25 X 2010, T. Yamasaki leg.; 1 male and 11 females, same loc., 16 XI 2010, T. Yamasaki leg.; 1 female, Mahua, Sabah, 27 XI 2010, T. Yamasaki leg. TAIWAN: 1 male and 1 female, Taichung, 1 V 2009, T. Yamasaki leg.; 4 males and 2 females, Nantou, 3 V 2009, T. Yamasaki leg. HONG KONG: 1 male and 1 female, 4–5 IV 2011, T. Suguro leg. VIETNAM: 1 female (MIZ 217147; labeled M. globosa ), Chine, 80 km SW Ha Noi, 24 VI 1959, B. Pisarski & J. Prószyński leg. NE. THAILAND: 1 female, Forestry camp, Wang Nam Kaeao dist., Nakhon Ratchasima prov., 17 VIII 2009, T. Yamasaki leg.; 1 female, Haui Nam Keam, Wang Nam Kaeao dist., Nakhon Ratchasima prov., 18 VIII 2009, T. Yamasaki leg. MALAY PENINSULA: 1 male, Batu Tujuk, Port Dickson, Negeri Sembilan, 25 XII 2010, T Maeda leg. SUMATRA: 1 male, Forest of Andalas University, Padang, 12 X 2008, Kei. Nakamura leg.; 1 male, Payakumbuh, 10 VII 2010, Ky. Nakamura leg.; 1 male, Forest of Andalas University, Padang, 17 VIII 2010, Ky. Nakamura leg. SULAWESI: 1 juvenile, Laiya, Labbang, Sulawesi, 24 I 2010, Sk. Yamane leg.

Diagnosis. Robust species, and body size, pilosity and coloration variable. In males, chelicera in dorsal view bearing two spurs on its inner margin ( Figs 30 A, D). In females chelicera outstandingly long among Asian species (more than 2 times as long as broad seen from above); copulatory atria large, round; spermathecae spherical; elongated median pocket present in front of epigastric furrow.

Measurements (male/female). Carapace length 2.37–4.00/2.65–3.35, width 1.58–2.67/1.68–2.00. Abdomen length 2.35–4.10/2.85–4.00. Chelicera length 1.65–4.15. Sternum length 1.37–2.40/1.57–1.97. Width of eye row I 1.38–1.95/1.53–1.78; II 1.20–1.78/1.35–1.58; III 1.48–2.10/1.68–1.98. ALE–PLE 1.08–1.60/1.25–1.43; ALE– PME 0.55–0.75/0.65–0.75. Eye size: AME 0.43–0.58/0.47–0.55, ALE 0.23–0.32/0.27–0.30, PME 0.08–0.10/0.08– 0.09, PLE 0.23–0.35/0.25–0.30.

Male ( Figs 30 A–G, 42A, 42C, 42E). Cephalic part weakly convex dorsally, and posterodorsal corner of cephalic part produced roundly above PLE; in dorsal view width of cephalic part much wider than eye row III. Thoracic part convex dorsally. Chelicera robust, with seven to ten prolateral and three or four small retrolateral teeth, and with two apical spurs on inner margin of chelicera, of which the more distal is very large. Fang thick, curved, without tooth-like apophysis. Sternum relatively broad, slightly overlapped by coxae I and II. Abdomen oval without constriction, and with broad dorsal scutum that is incised on each lateral outline anteriorly. Palp ( Figs 30 E–G). Tegulum oval with seminal reservoir along lower margin of tegulum. Embolus forming two oval coils; embolus coils occupying almost half of venter of cymbium. RTA weakly curved. Flange of RTA not developed well.

Leg spination. Tibia I pv 6–8, rv 5–7; metatarsus I pv 2, rv 1–2; femur II pd 0–2, rd 0–1; tibia II pv 2–3. rv 3; metatarsus II pv 2, rv 2; femur III pd 1, rd 0–1; femur IV pd 0–2, rd 1.

Coloration and pilosity. Three forms recognisable. Form I ( Figs 42 A–B): Carapace black, densely covered with white hairs except for diagonal area running from behind PLE to above coxa III. Chelicera black covered with white hairs. Maxilla and labium dark brown. Sternum brown. Coxa I brownish cream, tinged with dark brown on posterior margin; coxa II dark brown or black; coxae III and IV brown, tinged with black. Abdomen densely covered with hairs; dorsal scutum dark brown; integument except for scutum grey (in the field abdomen seems to be golden). Form II ( Figs 42 C–D): Carapace dark brown to black, sparsely covered with white small appressed hairs. Chelicera dark brown, covered with fine hairs. Maxilla, labium, sternum and coxae almost same as in Form I.

Abdomen sparsely covered with fine black hairs; dorsal scutum dark red; integument except for scutum greyish brown. Form III ( Figs 42 E–F): Carapace light brown except for black dorsum of cephalic part, and densely covered with white hairs except for diagonal area running from behind PLE to above coxa III. Chelicera dark brown, covered with white hairs. Maxilla, labium, sternum and coxae almost same as in Form I. Abdomen densely covered with fine hairs; dorsal scutum light brown anteriorly and black posteriorly; integument except for scutum cream and grey (in the field abdomen seems to be golden).

Female ( Figs 31 A–E, 42B, 42D, 42F). Cephalic and thoracic parts almost same as in males. Chelicera long, with seven to nine prolateral and ten to 14 retrolateral teeth. Sternum and abdomen almost same as in males.

Epigyne ( Figs 31 D–E). Copulatory atria containing openings large, round. Spermathecae spherical; sclerotised copulatory ducts weakly curved, without twist. Elongated median pocket present in front of epigastric furrow.

Leg spination. Tibia I pv 6–7, rv 6–7; metatarsus I pv 2, rv 2; tibia II pv 3, rv 3; metatarsus II pv 2, rv 2.

Coloration and pilosity. Three forms recognisable as in males ( Figs 42 B, 42D, 42F).

Distribution. Taiwan, Hong Kong, Vietnam (Żabka 1985), Thailand, Malay Peninsula (Badcock 1918), Luzon (Barrion & Litsinger 1995), Sumatra, Java (C. L. Koch 1846), Borneo, Sulawesi (Thorell 1877).

Remarks. Although we did not examine the type material of Toxeus maxillosus , Dr. G. B. Edwards showed us pictures of type material, which agreed with the specimens in our collection (personal communication, 2010).

Myrmarachne maxillosa is easily recognisable by the long leg I and the robust carapace. The species shows variation in body size, coloration and pilosity. Form I is relatively small and covered with dense hairs. From II and III are almost same in body size, but different in coloration and pilosity. These varieties occur in the same sites, rarely with intermediate forms. In spite of difference in coloration, all these forms share the conditions of many morphological characters (e. g., the dentition of the chelicera, the structures of the male palp and female epigyne). We therefore concluded that the three forms to belong to a single species. Many species that appear to be one of the forms of M. maxillosa are recorded from Southeast Asia, for example, M. aureonigra Edmunds & Prószyński, 2003 , M. caliraya Barrion & Litsinger, 1995 , M. hirsutipalpi Edmunds & Prószyński, 2003 and M. magna Saito, 1933 . Although they would be synonyms of M. maxillosa , these names are retained here because we did not examine their type material.

In Żabka (1985), M. globosa was redescribed based on a single female specimen (MIZ 217147). Although we did not examine the type material of M. globosa , the rescription by Żabka (1985) agree with our specimens of M. maxillosa .

Although the males used in the original description of M. gigantea by Żabka (1985) are undoubtedly M. maxillosa , the single female mentioned by him as allotype should belong to a different species, probably M. vestita (Thorell 1895) . We compared the syntypes of M. vestita (BMNH) with the description of the M. gigantea female, finding that they are very similar to each other in body shape, and the structure of the pedicel (projection present) and epigyne.

Biology. The species often occurs in lower vegetation of open areas. The male and female make their retreat on the upper surface of a leaf, which is rolled up by them with opposite edges loosely woven with threads. When adult females oviposit in retreats, the woven portion is made more tightly and the space is completely closed.

Myrmarachne maxillosa in external appearance resembles ants of the genus Polyrhachis . Coloration of Form I generally resembles many black Polyrhachis species with golden abdomen. Form II is very similar to the workers of P. armata Le Guillou and P. abdominalis F. Smith which have reddish abdomen, and Form III to P. bihamata Drury.

Figures

FIGURE 42. Colour variation of M. maxillosa. A, Form I, male, Sumatra. B, Form I, female, Borneo. C, Form II, male, Borneo. D, Form II, female, Borneo. E, Form III, male, Sumatra. F, Form III, female, Borneo. (B, C and F were collected from the same sites in Borneo) (Scales. A – F: 1 mm / division)

FIGURE 30. M. maxillasa, male. A, body, dorsal view; B, chelicera and carapace, lateral view; C, maxillae, labium, sternum and coxae; D, chelicera and fang, ventral view; E, palp, ventral view; F, palp, lateral view; G, palpal tibia, dorsal view. (Scales. A – D: 1 mm; E – G: 0.25 mm)

FIGURE 8. M. biseratensis, male. A, body, dorsal view; B, chelicera and carapace, lateral view; C, chelicera and fang, ventral view; D, maxillae, labium, sternum and coxae; E, palp, ventral view; F, palp, lateral view; G, palpal tibia, dorsal view. (Scales. A – D: 1 mm; E – F: 0. 25 mm)

FIGURE 4. M. alticephalon sp. nov., male. A, body, dorsal view; B, chelicera and carapace, lateral view; C, chelicera and fang, ventral view; D, maxillae, labium, sternum and coxae; E, palp, ventral view; F, palp, lateral view; G, palp, dorsal view. (Scales. A – D: 1 mm; E – G: 0.25 mm)

FIGURE 31. M. maxillosa, female. A, body, dorsal view; B, chelicera and carapace, lateral view; C, maxillae, labium, sternum and coxae; D – E, internal structure of epigyne, ventral view. (Scales. A – C: 1 mm; D: 0.25 mm; E: 0.10 mm)