Description of instar III larva of M. panaminti (Fall, 1923)

(Figs 3–15)

Source of material. The larvae studied were collected ex societate imaginis (Fig. 2) at the following locality: USA: California. Inyo Co.: Death Valley National Park, Badwater Basin, off Badwater Road, ca. 27 km south of California Route 190, 11.iv.1999, 36°13.801′N 116°46.064′W, 15 instar III, Y.Alarie leg. The identification was safe as M. panaminti is the only dytiscid collected at that location .

Diagnosis: Instar III larva of M. panaminti can readily be distinguished from that of M. coelamboides by its smaller size, HL = 0.88–0.95 mm, HW = 0.65–0.71 mm, U1 = 1.98–2.20 mm (Table 1), lesser number of secondary setae along anteroventral margin of metafemur (<12) and metafemur as a whole (<42) (Table 2), and narrower abdomen (Fig. 3).

Body (Fig. 3): Measurements and ratios that characterize the body shape are shown in Table 1.

Head (Figs 4–13): HL = 0.88–0.95 mm, HW = 0.65–0.71 mm, FRL = 0.67–0.72 mm, OCW = 0.43–0.48 mm; ventroapical margin of frontoclypeus with 31–35 spatulate setae [= lamellae clypeales of Bertrand (1972)].

Thorax (Figs 3, 14–15): L3 = 2.47–2.68 mm.

Abdomen (Figs 3, 5–6): LAS (Fig. 5) = 0.32–0.33 mm. Urogomphus (Fig. 6). U1 = 1.98–2.20 mm, U1+ U2 = 2.20–2.50 mm, U1/U2 = 5.79–7.27.

Chaetotaxy: Lateroventral margin of PA with 6–8 secondary spine-like setae (Fig. 4); secondary leg setation detailed in Table 2 and Figs 14–15.

Ecology: Adult and larval specimens of M. panaminti (Figs 2–3) were collected from water slowly flowing below salt crust.

Distribution: So far only known from Death Valley National Park, California, USA (Zimmerman & Smith 1975).