Notiphila nanosoma Mathis 1979

Notiphila (Dichaeta) nanosoma

DIAGNOSIS.—Specimens of N. nanosoma resemble those of both N. minima and N. atripes but differ from either by the following combination of characters: Legs unicolorous, entirely black, except for setal fascicle of the hind basitarsus which is pale, amber; fascia of abdominal terga broad, especially on fourth and fifth terga where they cover most of the dorsum. Specimens of N. nanosoma are smaller on the average than members of N. atripes and the genitalia of N. nanosoma males are quite distinct: Hypandrial process broader and preapical enlargement not as extensive or prominent. Other differences in the male genitalia may be noted in the shapes of the aedeagal apodeme, which is rounded dorsally in N. minima males, and the surstyli (Figures 165–166).

DESCRIPTION.—Moderately small to medium-sized shore flies, length 2.56 to 3.46 mm; with grayish coloration and black markings.

Head: Head ratio 1:0.76; postfrons ratio 1:0.58; extreme lateral margin of frons whitish gray, otherwise most of lateral margins concolorous with median triangular area; remainder of frons subdued, black, lightly pollinose. Paravertical bristle slightly larger than postocellar setae; 2 pair of proclinate, fronto-orbital setae. Antenna entirely black; arista with 8–10 dorsal branches. Face light grayish yellow; prefrons ratio 1:0.56; facial setae small, hairlike. Eye ratio 1:0.80; eye-to-check ratio 1:0.16. Gena narrow, concolorous with face anteriorly, becoming gray posteriorly. Maxillary palpus black.

Thorax: Thorax light brownish gray, pleural areas grayer than mesonotum; mesopleuron and mesonotum immaculate although some specimens with very light, vittate markings on mesonotum. Legs entirely grayish black to black. Setal fascicle of hind basitarsus pale, amber. Wing ratio 1:0.42; costal ratio 1:0.60; M1+2 vein ratio 1:1.20.

Abdomen: Abdomen ratio of males 1:0.63; length of fourth tergum to fifth tergum ratio of males 1:1; fifth tergum ratio of males 1:0.61. Fascia of abdominal terga black; first and second terga mostly gray; third tergum approximately half and half; fourth tergum mostly black except for a median gray area; fifth segment entirely black. Male terminalia as in Figures 165–166.

TYPE-MATERIAL.—Holotype male: “CALIF(ornia) Nevada Co. 5 mi [8.1 km] NW Hobart Mill 20 June 1974 Wayne N. Mathis/HOLOTYPE Notiphila nanosoma Mathis (red).” Allotype female and 79 paratypes (41 , 37 ): with same label data as the holotype. Other paratypes as follows: 3 , 1 , California, Nevada Co., 4 km NW Hobart Mills, 20 June 1974, Wayne N. Mathis (WNM); 10 , 10 , California, Nevada Co., Sagehen Creek, near Hobart Mills, dates: 20 June 1954, 25 June 1954, June 1954, 4 July 1962, 18 July 1967, collectors: M. T. James, R. H. Goodwin, C. A. Toschi, W. J. Turner (UCB, USNM, WSU); 9 , 11 , Oregon, Deschustes Co., 24.2 km S Sisters, 8 August 1973, 10 July 1972, Wayne N. Mathis (WNM). The holotype will be deposited in the National Museum of Natural History, Smithsonian Institution, Washington, D. C., type number 73545.

ETYMOLOGY.—The epithet nanosoma, of Greek derivation, is a combination of the nouns nanos (“dwarf”) plus soma (“body”) in reference to the small body size.

GEOGRAPHIC DISTRIBUTION.—This species has been collected in the Sierra Nevada Mountains of California and in the Cascade Mountains of Oregon.