Lachesilla byei n. sp.

(Figs 1−5)

Diagnosis. Claspers large, curved, acuminate. Phallosome apodemes very long, independent, proximally slender, widening anteriorly, acuminate. Flap of the subgenital plate narrow anteriorly, slightly extended on each side, wider in the middle, the distal concavity about one fourth the length of the flap. The claspers are reminiscent to those of L. sommermanae García Aldrete, from the Mexican states of Chiapas, Guerrero, Michoacán and Nuevo León, all distant from the Sierra Tarahumara, but the flap of the subgenital plates are distinct; the flap of the subgenital plate is similar to that of L. yakima Mockford and García Aldrete, from Canada and the northamerican states of California, Utah, Washington and Wyoming.

Male. Color (in 80% ethanol). Body tawny brown. Compound eyes black, ocelli hyaline, with pale brown centripetal crescents, antennal fossae surrounded by an ochre rim. Maxillary palps and legs pale brown. Tergal lobes of meso- and metathorax slightly more pigmented. Abdomen with light brown, transverse subcuticular bands.

Morphology. Compound eyes above the level of the vertex, this concave in the middle. Forewings with Rs-M fused for a short length. Pterostigma wider distally, areola postica tall, apically rounded (Fig. 1). Hindwings as in Fig. 1. Hypandrium, claspers and phallosome apodemes as in Fig. 4. Paraprocts semicircular, setose as illustrated (Fig. 2), mesal prong mid-sized, distally pointed, sensory fields rounded, with 9−10 trichobothria in basal rosettes, and a marginal trichobothrium without basal rosette. Epiproct (Fig. 2) broadly trapeziform, with setae as illustrated.

Measurements. FW: 3847, HW: 1329, F: 505, T: 918, t1: 304, t2: 111, ctt1: 18, Mx4: 115, f1: 589, f2: 517, f3: 435, f4: 347; f5: 199, f6: 166, f7: 149, f8: 122, f9: 103, f10: 95, f11: 105, IO: 314, D: 117, d: 144, IO/d: 2.18, PO: 1.23.

Female. Color. Same as in the male.

Morphology. Compound eyes below the level of the vertex, this straight. Subgenital plate (Fig. 3) broad, straight anteriorly, with sides converging to straight posterior border, posterior third glabrous, with one macroseta near each side. Mesal flap long (Fig. 3) as described in Diagnosis.

Gonapophyses and ninth sternum lost in preparation. Paraprocts (Fig. 5) almost elliptic, setae as illustrated, sensory fields rounded, with 10−11 trichobothria in basal rosettes, and one marginal trichobothrium without basal rosette.

Measurements. FW: 2852, HW: 2132, F: 576, T: 1145, t1: 395, t2: 110, ctt1: 14, Mx4: 105, f1: 437, f2: 389, f3: 299, f4: 216, f5: 137, f6: 119, f7: 96, f8: 85, f9: 88, f10: 78, f11: 85, IO: 398, D: 183, d: 133, IO/d: 2.99, PO: 0.72.

Specimens studied. Holotype male, 1 paratype female. MEXICO. Chihuahua. Sierra Tarahumara, 5 km SE Samachique, 27º16.804’N: 107º27.721’W, 2416 m, 13.XI.2002, Beating oak foliage, J. A. Casasola González.

Etymology. This species is dedicated to the ethnobotanist Dr. Robert Bye Boettler, of the Botanical Garden, Instituto de Biología, UNAM, in recognition to his many and diverse seminal studies conducted in the Sierra Tarahumara over the last 50 years.