Myrmecotypus iguazu, Rubio, Gonzalo D. & Arbino, Manuel O., 2009

Rubio, Gonzalo D. & Arbino, Manuel O., 2009, The first Myrmecotypus O. P. - Cambridge (Araneae: Corinnidae) from Argentina: description of Myrmecotypus iguazu new species, Zootaxa 2158, pp. 65-68 : 66-68

Myrmecotypus iguazu sp. nov.

Figs. 1 – 12

Type material. Holotype male (MACN-Ar 19708) and paratype (allotype) female (MACN-Ar 19709) from Iguazú National Park (25º41´S, 54º26´W), Misiones Province, ARGENTINA, 8 January 2009, G. Rubio and M. Arbino coll. Paratypes: same locality, 15 January 2005, G. Rubio coll., one male (CARTROUNNE 7818); same locality, 8 January 2009, G. Rubio and M. Arbino coll., one male ( CDA 000.806), three females ( CDA 0 0 0.807, CDA 0 0 0.808, CDA 000.810), one female ( MLP 17926); same locality, 20 January 2005, G. Rubio coll., one male ( CDA 000.811); Urugua-í Wildlife Reserve (25º59´S, 54º05´W), Misiones Province, ARGENTINA, 7 March 2009, G. Rubio coll., one female ( CDA 000.809).

Etymology. The specific name is a noun in apposition that refers to the type locality: Iguazú National Park, Misiones Province, Argentina.

Diagnosis. Myrmecotypus iguazu sp. nov. resembles M. pilosus O.P.-Cambridge 1898 by having tibia I ventral spination 3-3, and only coxae II translucent white, but can be distinguished from this species by its great body size and the male and female genital structure ( Figs. 1–9 ). Differs from other Myrmecotypus species by a combination of the following characters: only coxae II white ( Figs. 1–4 ); chelicerae with two retromarginal teeth and two promarginal teeth ( Fig. 10 ). In addition, it differs from all of them by its great size, except M. rettenmeyeri Unzicker 1965 , from which it differs by the male genitalia ( Figs. 5–7 ) and by the lack of a longitudinal row of dense hairs in the thoracic region ( Fig. 3 ).

Description. Male (holotype). Total length 7.08; carapace length 3.85; carapace width 1.67; carapace index 43.38; sternum length 1.73; sternum width 0.80; sternum index 46.24. Femur IV length 3.14; femur IV width 0.52; leg thickness index 16.56; leg length index 81.56. Abdomen length 2.96; abdomen width 2.04; abdomen index 68.92. Pedicel length 0.27. Embolus length 0.076; bulb length 0.97; male genital index 7.85. Carapace long and narrow, deep reddish-black, with a moderate constriction between the cephalic and thoracic regions, covered with refractory golden pubescence reinforced on the sides and groove region. Four faint black hairy narrow bands starting at the groove region and running laterally toward both sides ( Figs. 1, 3 ). Eyes small and equally sized, except anterior median eyes about two times the diameter of anterior lateral eyes. Both rows of eyes slightly recurved, posterior row about one-third wider than anterior row ( Fig. 1 ). Carapace somewhat narrowed in head region (cephalic width index 76.05). Abdomen oval (wider posteriorly) and completely covered by a deep reddish-black dorsal sclerite with refractory golden pubescence, and two faint thin transverse black bands ( Figs. 1, 3 ). Few sparse, moderately plumose short white hairs over the dorsum. Epigastric sclerite not extending to spinnerets, and inframammillary sclerite reddish-black. Abdomen very slightly petiolated (only a pair of lateral notches) ( Fig. 3 ). Two pairs of abdominal setae anteriorly, first pair thin and long, second moderately thick and more separate to each other that the first. Sternum reddish-black, elongate, with isolated thin white hairs. Chelicerae reddish-black with internal edge orange, with two moderately small retromarginal teeth and two promarginal teeth. Fangs red. Only coxae II translucent white, remaining coxae brown-black ( Figs. 1, 3 ). Trochanter I and II yellow-orange ventrally (II lighter than I), trochanter IV notch absent. Metatarsi I red-brown proximally and yellow-brown distally, tarsi yellow-brown (leg II somewhat darker). Remaining legs brown-black and moderately hirsute. Tibiae and metatarsi IV hirsute, with heavy black hairs, especially on ventral side. Tibia I ventral spination: 3-3, moderately long and thin. Leg formula: IV-I-III-II. Pedipalp with a blunt and very short tibial apophysis ( Figs. 5, 7 ). Tarsus with a globose genital bulb drawn out into a long neck with a small, twisted, sclerotized embolus; palpal ducts with two loops both lateral to the embolus tube ( Fig. 6 ).

Female (paratype [allotype]). Total length 9.68; carapace length 5.03; carapace width 2.12; carapace index 42.15; sternum length 2.31; sternum width 0.87; sternum index 37.66. Femur IV length 4.25; femur IV width 0.64; leg thickness index 15.06; leg length index 84.49. Abdomen length 4.13; abdomen width 3.25; abdomen index 78.69; dorsal sclerite length 1.37; dorsal sclerite width 1.06; dorsal sclerite index 77.37. Pedicel length 0.52. Carapace as in male. Four faint black thin hair bands starting at groove region and running laterally toward both sides ( Figs. 2, 4 ). Eyes and eyes rows as in male. Cephalic region narrower than thoracic region (cephalic width index 81.13). Abdomen pear-shaped, wider posteriorly, with a moderately small, reddish-black dorsal sclerite. Hair covering as in male ( Figs. 2, 4 ). Epigastric and inframammillary sclerites yellow-brown. Abdomen very slightly petiolated (only a pair of lateral notches) ( Fig. 2 ). Abdominal setae and sternum as in male. Chelicerae reddish-black (orange internal edge) with two retromarginal teeth, the distal slightly smaller than the proximal, and two promarginal teeth, the distal larger than the proximal ( Fig. 10 ). Fangs red. Only coxae II white, rest brown-black ( Figs. 2, 4 ). Trochanter I and II orange-brown ventrally (in II more light than I), trochanter IV notch absent. Metatarsi I red-brown proximally and yellow-brown distally, tarsi yellow-brown (leg II somewhat darker). Remaining legs as in male. Leg formula as in male.

Variation. Males (four): total length 6.05 – 7.28; carapace length 3.16 – 3.92; carapace width 1.56–1.80; sternum length 1.54 – 1.82; sternum width 0.74 – 0.88. Femur IV length 2.45 – 3.40; femur IV width 0.45 – 0.52. Abdomen length 2.69 – 3.08; abdomen width 1.84 – 2.18. Pedicel length 0.20 – 0.45. Bulb length 0.83 – 1.02. Dorsal sclerite cover full to 95%. Females (six): total length 9.68 – 8.34; carapace length 5.06 – 4.40; carapace width 2.16 – 1.94; sternum length 2 – 2.50; sternum width 0.87 – 1.04. Femur IV length 3.56 – 4.31; femur IV width 0.50 – 0.64. Abdomen length 3.36 – 4.13; abdomen width 2.68 – 3.25; dorsal sclerite length 1.04 – 1.80; dorsal sclerite width 1.06 – 1.24; the abdomen can be slightly oval. Pedicel length 0.32 – 0.56. The refractory pubescence of carapace and abdomen can be all golden or all silvery.

Natural history. In Arbino & Rubio (in prep.) we have studied part of the natural history of Myrmecotypus iguazu . This species is an ant-mimic spider, males or females with golden or silvery pubescence, that has specialized mimicry to the ant Camponotus sericeiventris Guérin 1838 . They have a single species as their model and their mimetic modifications are clearly associated with that species ( Figs. 11 – 12 ). Although the ant has a wide distribution almost occupying the whole Neotropical area ( Wheeler 1931; Kempf 1972; Fernández & Sendoya 2004), we corroborate the coexistence with M. iguazu in the Argentinean NE. In this way M. iguazu is an ecological equivalent of the spider M. rettenmeyeri from Panama (Arbino & Rubio in prep.).

Distribution. This species is the southern most representative of the genus and is hitherto known from the type locality in Iguazú National Park and from Urugua-í Wildlife Reserve, Misiones Province, Argentina.

Figures

FIGURES 1 – 10. Myrmecotypus iguazu sp. nov. 1 – 4, body view (1, male dorsal; 2, female dorsal; 3, male lateral; 4, female lateral). 5 – 7, left male palp (5, prolateral; 6, ventral; 7, retrolateral). 8 – 9, epigynum (8, ventral view; 9, dorsal view). 10, chelicerae (ventral view of female). (LN = lateral notches; DS = dorsal sclerite; Co = coxa II; AS = abdominal setae; TAB = transverse abdominal bands; E = embolus; SD = sperm duct; CO = copulatory opening; RT = retromarginal teeth; PT = promarginal teeth). Scale bars: 1 – 4, 1 mm; 5 – 7 and 10, 0.5 mm; 8 – 9, 0.25 mm.

FIGURES 11 – 12. Myrmecotypus iguazu sp. nov. Habitus in nature (Iguazú National Park, 2009).