Figs 61–63, 96
Type material. Female holotype and male paratype from Argentina, Entre Ríos, Diamante, Parque Nacional Predelta, sendero a Laguna Las Piedras, S 32.12462º, W 60.6277º, 23–26.V.2011, G. Rubio, L. Piacentini & M. Izquierdo, temporary preparations MGM-00335, MGM-00336, MGM-00337, deposited in MACN-Ar (MACN-Ar 28323).
Etymology. The specific name is a noun in apposition taken from the word “northwest men” in the language of the Chaná, indigenous inhabitants of Uruguay and northern Argentina, in honor of the collectors of the type series.
Diagnosis. Males (Figs 61h, 62, 63c) resemble those of M. arcifera and M. decepta by the elongate abdomen and the oval shape of the bulb, but differ from the former by the blunt RTA covered by small bumps, and from the latter by the dark rings on the legs. Females (Figs 61 a–g, 63a, b, d) resemble those of M. arcifera by the epigyne lacking a hood and having a wide median field and large, almost contiguous S2, but can be easily recognized by the arc-shaped epigynal lateral ridges.
Description. Female (holotype): Carapace length 1.77, width 1.43, narrowed in eye region. Palpal tarsus length 0.45. Sternum length 1.12, width 0.90. Length of tibia/metatarsus: I, 1.35/1.07; II, 1.08/0.90; III, 0.65/0.82; IV, 1.30/1.25. Spines: Leg I, femur p 1ap. IV, femur d 1bas; metatarsus v 0-1-0. Leg cuspules absent. Opisthosoma length 2.63. Color in ethanol: Prosoma reddish-brown, lighter distally. Chelicerae reddish-brown. Legs yellowish-brown, leg I darker. Anterior femora with subbasal and distal dark rings, posterior femora with vague traces of dark rings. All patellae with subdistal, all tibiae with subbasal and distal, all metatarsi with subbasal and distal dark rings. Sternum brown. Opisthosoma grayish-brown, with dark reticulations. Venter grayish. Epigyne (Figs 63 a–b): Arc-shaped epigynal lateral ridges. Copulatory openings in anterior position; copulatory ducts very short, secondary spermathecae large and oval, receptacle of copulatory ducts very small and rounded, behind primary spermathecae. Primary spermathecae rounded and larger than CDR.
Male (paratype): Carapace length 1.87, width 1.40, narrowed in eye region. Palpal tarsus length 0.53. Sternum length 1.13, width 0.94. Length of tibia/metatarsus: I, 1.58/1.33; II, 1.03/0.93; III, 0.72/0.83; IV, 1.13/1.38. Spines: Leg I, femur p 1ap. II, femur p 1ap. III, metatarsus v 0-1-0. IV, femur d 1bas; metatarsus v 0-1-0. Leg cuspules (left or right): Leg I, tibia 5 or 7, metatarsus 15, tarsus 6. II, tibia 5 or 4, metatarsus 8 or 6. Opisthosoma length 2.34. Opisthosoma with dorsal oval, slightly sclerotized area, limited to posterior half of abdomen. Coloration as in female. Palp (Figs 62 g–i, 63c): Tibia short. RTA short, blunt, covered by small bumps. Embolus short, slightly curved to retrolateral.
Natural history and habitat. The specimens were collected beating the foliage of Tessaria integrifolia (“aliso”), Mikania cordifolia, Cayaponia citrullifolia and Ephedra tweediana (“enredaderas”).
Distribution. Only known from the type locality in Entre Ríos province (Fig. 96).
Other material examined. ARGENTINA: Entre Ríos: Diamante: Parque Nacional Predelta, bosque de barranca, S 32.12034°, W 60.62958°, elev. 26 m, 23–26.V.2011, beating shrubs, G. Rubio, L. Piacentini & M. Izquierdo, 2 females, 1 male (MACN-Ar 33089). Parque Nacional Predelta, sendero a Laguna Las Piedras, 6 km S de Diamante (MJR-loc-140), S 32.12438°, W 60.63002°, elev. 6 m, 29.IV–1.V.2013, forest of Tessaria integrifolia (“aliso”), Mikania cordifolia, Cayaponia citrullifolia and Ephedra tweediana (“enredaderas”), beating shrubs, M. Ramírez, L. Piacentini, M. González Márquez, A. Laborda & S. Aisen, 1 female, sample MGM-00145 (MACN-Ar 30283), 1 female, sample MGM-00146 (MACN-Ar 30284), 1 female, sample MGM-00148 (MACN-Ar 30286), 1 female, sample MGM-00152 (MACN-Ar 30290). Parque Nacional Predelta, sendero a Laguna Las Piedras, S 32.12462°, W 60.6277°, elev. 12 m, 23–26.V.2011, hand collection, G. Rubio, L. Piacentini & M. Izquierdo, 1 female, sample MAI-00719, temporary preparation ASE-00015 (MACN-Ar 28319), 3 females, 1 male, temporary preparations MGM-00335–00337 (MACN-Ar 28323), 1 female (MACN-Ar 33088).