Oecetis mexicana, Blahnik, Roger J. & Holzenthal, Ralph W., 2014

Blahnik, Roger J. & Holzenthal, Ralph W., 2014, Review and redescription of species in the Oecetis avara group, with the description of 15 new species (Trichoptera, Leptoceridae), ZooKeys 376, pp. 1-83 : 44-47

Oecetis mexicana sp. n. Figs 18, 19, 20, 50, Map 4

Diagnosis.

This is one of the most widespread species in the Neotropical material formerly included within Oecetis avara . Although common in Mexico it also extends into Panama and even to Ecuador, but seems to be somewhat less common in the southern part of its distribution, where it is often replaced by other species in the Oecetis avara group. Taken as a whole, the species is more variable than most of the species of the Oecetis avara group from Central and South America. Oecetis mexicana has the same generalized genitalic structures as Oecetis avara and Oecetis houghtoni sp. n. including a short phallobase, arched ventrally and with a U-shaped ventral apex (as viewed caudally) and an asymmetric apical phallic sclerite. It differs primarily in its smaller size, yellow coloration and prominent, rounded forewing spots, and by the obtuse to right angled ventral lobe of the inferior appendages (Figs 18A and 19A). In general form of the genitalia, it comes close to some specimens from eastern USA, currently unassigned to species (see discussion of unassigned material at end of species descriptions), which also have inferior appendages with the ventral margin obtusely angled (Fig. 28A). These, however, are much darker in color and have only indistinct forewing spots. The most similar species to Oecetis mexicana , within the zone of sympatry, are Oecetis constricta and Oecetis campana , which also have inferior appendages that are obtusely angled and are similar in size. Oecetis constricta is separated by having the apex of the phallobase distinctively “pinched,” as viewed caudally and usually has the phallobase more angularly bent, as well as being slightly smaller in size. In one population assigned to Oecetis constricta from Carara in Costa Rica (but not included in the paratype series), specimens lacked the “pinched” apex of that species and thus were similar to Oecetis mexicana . These specimens were discussed in the diagnosis for Oecetis constricta . Oecetis mexicana also closely resembles Oecetis campana sp. n., which differs primarily in that the ventral margin of the phallobase is nearly straight rather than arched or angled (see the diagnosis for Oecetis campana for other minor differences).

Adult.

Forewing length: male (6.5-8.0 mm), female (5.8-7.5 mm). Color yellowish, palps very slightly darker. Antennae pale yellow with indistinct, narrow annulations at intersection of antennomeres. Forewing spots distinct and large; spots at base of discal and thyridial cells largest, spot at base of fork V nearly as large; veins of forewing chord widely and usually nearly evenly spaced, with crossveins nearly perpendicular, or s and r-m veins slightly closer; chord with small spots at juncture of major veins, those at opposite ends of chord larger; apical spots, at apices of major veins prominent, pigmentation extending beyond veins. Setae along veins in apical part of forewing elongate, semi-prostrate, laterally diverging. Fringe of setae along costal margin of forewing moderately dense, elongate, suberect.

Male genitalia.

Segment IX very short, with elongate setae along posterolateral margin. Tergum X with narrow, deflexed mesal lobe, lobe relatively elongate, uniform in width or somewhat lobulate apically, apex with small sensilla; lobe continuous basoventrally with short paired lateral membranous projections. Preanal appendage moderately elongate, length about 3 times maximum width, simple in structure, apical setae elongate. Inferior appendage with prominent rounded dorsal lobe and angularly projecting ventral lobe; ventral lobe moderately projecting, forming approximately right to distinctly obtuse angle with dorsal lobe, posterior margin of ventral lobe, as viewed ventrally (Fig. 18F), with distinctly angular bend near base; basomesal projection very weakly developed, scarcely or not protruding, with short, stiff setae; dorsal lobe with stout, mesally-curved setae on dorsal margin and stout, ventrally-curved setae on mesal surface. Phallobase, as viewed laterally, short and tubular, distinctly curved or “arched” ventrally (not angular); apex, as viewed caudally, with ventral margin U-shaped, not keeled ventrally (Fig. 18C), rarely narrowly U-shaped (Fig. 19C), apex not ridged or “burred.” Phallotremal sclerite prominent, basally forming short tubular collar, ventral margin projecting, apex acute; asymmetrical lateral sclerite present, usually distinctly protruding, located on right side, or sometimes on left.

Holotype.

Male (pinned), MEXICO: Chiapas: Río Tulija, 48 km S Palenque, 17.v.1981, C.M. & O.S. Flint, Jr. (NMNH) (UMSP000208191).

Paratypes.

MEXICO: Chiapas: same data as holotype, 8 males, 4 females (pinned), 3 males, 1 female (alcohol) (NMNH); Río Contento, 7 km N Ocosingo, 20.v.1981, C.M. & O.S. Flint, Jr., 6 males, 6 females (pinned), 13 males, 4 females (alcohol) (NMNH); Cascada Misolja, 20 km S Palenque, 17-18.v.1981, C.M. & O.S. Flint, Jr., 1 male (pinned) (NMNH); Río Lacanja, 22 km N Ocosingo, 19.v.1981, C.M. & O.S. Flint, Jr., 3 males, 2 females (pinned) (NMNH); Oaxaca: Río Valle Nacional, Chiltepec, 25.v.1981, C.M. & O.S. Flint, Jr., 6 males, 6 females (alcohol) (NMNH); Ao. Choapan, Bethania, 31 km S Tuxtepec, 24.v.1981, C.M. & O.S. Flint, Jr., 5 males, 4 females (pinned) (NMNH); San Luis Potosí: Palitla, 5.vi.1966, O.S. Flint, 2 males, 7 females (alcohol) (NMNH); 25 mi N Tamazunchale, el 400 m, 3-4.viii.1963, Duckworth & Davis, 1 male (alcohol) (NMNH); Huichhuayan, 4.vi.1967, O.S. Flint, Jr., 2 males (pinned) (NMNH); Tamaulipas: Río Corona, 18 mi N Ciudad Victoria, 13.iii.1982, J.E. Gillaspy, 1 male, 1 female (alcohol) (NMNH); Veracruz: nr. El Encero, Rt. 140, km 347, 22.vii.1965, Flint & Ortiz, 1 male (pinned) (NMNH); BELIZE: Cayo: Río Privassión, 14.vii.1973, Y. Sedman, 1 male, 1 female (alcohol) (NMNH); HONDURAS: Río Humuya, NW Comayagua, 3.viii.1967, O. S. Flint, Jr., 1 male (pinned) (NMNH); Olancho: Río Agua Amarilla, Pacayal, 5 km S El Carbon, 27.vii.1989, O.D. L. Lentz & Lopez, 1 male (alcohol) (NMNH); NICARAGUA: Zelaya: Cerro Saslaya, 13°44'N, 85°01'W, el 700 m, --iv.1996, J. M. Maes & J. Hernandez, 3 males, 15 females (alcohol) (NMNH); COSTA RICA: Alajuela: Río Pizote, ca. 5 km N Dos Ríos, 10°56.880'N, 85°17.460'W, el 470 m, 9.iii.1986, Holzenthal & Fasth, 33 males, 9 females (alcohol) (UMSP); Río Pizote, ca. 5 km (air) S Brasilia, 10°58.320'N, 85°20.700'W, el 390 m, 12.iii.1986, Holzenthal & Fasth, 8 males, 15 females (alcohol) (UMSP); Guanacaste: Parque Nacional Guanacaste, El Hacha, Quebrada Pedregal, 10°58.980'N, 85°32.340'W, el 300 m, 27.vii.1987, Holzenthal, Morse, Clausen, 1 male (pinned) (UMSP); Río Aguacate, 0.5 km E Aguacate, 10°33.900'N, 84°56.340'W, el 590 m, 16.ii.1992, Holzenthal, Muñoz, Kjer, 2 males, 2 females (pinned) (UMSP); Río Mena, 4.2 km W Santa Cecilia, 11°3.540'N, 85°26.880'W, el 260 m, 11.iii.1986, Holzenthal & Fasth, 4 males (alcohol) (UMSP); Heredia: Quebrada Ceiba, 6 km E Cháves, 10°22.920'N, 83°55.320'W, el 50 m, 2.vii.1992, F. Muñoz, 3 males (pinned) (INBIO); Río Sarapiquí, 300 m S Chilamate, 10°26.160'N, 84°3.600'W, el 40 m, 30.vi.1991, F. Muñoz, 3 males, 2 females (pinned) (INBIO); Río Bijagual, 3.5 km S Chilamate, 10.436°N, 84.060°W, el 40 m, 1.vii.1992, F. Muñoz, 3 males (pinned) (INBIO); Est. Biol. La Selva, Quebrada Sura, 10°26.220'N, 84°0.600'W, el 50 m, 20-21.vi.1986, Holzenthal, Heyn, Armitage, 3 males (alcohol) (UMSP); Limón: E.A.R.T.H., Río Dos Novillos, 10°13.200'N, 83°35.460'W, el 20 m, 3.ii.1992, Holzenthal, Muñoz, Kjer, 12 males, 7 females (pinned) (UMSP); same location, 26.vi.1992, Contreras & Muñoz, 3 males (pinned) (UMSP); E.A.R.T.H., Río Parismina, 10°14.880'N, 83°34.200'W, el 5 m, 4.ii.1992, Holzenthal, Muñoz, Kjer, 19 males, 2 females (pinned) (UMSP); E.A.R.T.H., Río Destierra, Pozo Azul, 10°12.480'N, 83°34.440'W, el 15 m, 5.ii.1992, Holzenthal, Muñoz, Kjer, 20 males, 5 females (pinned) (UMSP) (INBIO); same location, 27.vi.1992, F. Muñoz, 5 males (pinned) (INBIO); Puntarenas: Río Singri, ca 2 km (air) S Finca Helechales, 9°3.420'N, 83°4.920'W, el 720 m, 21.ii.1986, Holzenthal, Morse, Fasth, 1 male (alcohol) (UMSP); PANAMA: Canal Zone: Pipeline Rd., --vii.1967, W. Wirth, 1 male, 1 female (pinned) (NMNH); Darien: Río Tuira, between El Real & Río Pucuro, 16.ii.1985, J. Louton, 2 males (pinned), 1 male, 12 females (alcohol) (NMNH); Río Tuira at Río Pacuro, 16-17.ii.1985, J. Louton, 5 males, 2 females (pinned) (NMNH); Río Tuira, at Boca de Cupe, 18.ii.1985, J. Louton, 1 male (alcohol) (NMNH); San Blas: Río Carti Grande, nr. coast, 2.iii.1985, Flint & Louton, 12 males (pinned), 24 males, 28 females (alcohol) (NMNH); ECUADOR: Los Ríos: Quevedo, 11.v.1975, Spangler, Gurney, Langley & Cohen, 2 males, 8 females (alcohol) (NMNH); Quevedo, 56 km N, Río Palenque Biol. Sta., el 250 m, 18-29.vii.1976, J. Cohen, 7 males, 1 female (alcohol) (NMNH); VENEZUELA: Lara: Parque Nactional Terepaima, Quebrada San Antonio, 9°51.754'N, 69°13.098'W, el 631 m, 17.vi.2001, Holzenthal, Blahnik, Paprocki, Cressa, 1 male (pinned) (UMSP).

Etymology.

This species is named Oecetis mexicana for Mexico, the country of origin of the holotype specimen, where this species seems to be especially abundant and widespread.