Leucon (Leucon) americanus Zimmer 1943

Leucon americanus Zimmer

Leucon americanus Zimmer, 1943:159–160.

DESCRIPTION OF ADULT FEMALE.—Length of largest specimen about 5 mm.

Thorax (Figure 37) somewhat longer than abdomen including its last segment. Carapace about as long as first 4 abdominal segments combined, sharply pointed in dorsal view (Figure 38). Pseudorostrum relatively long, almost 1/3 length of carapace from anterior margin of frontal lobe to posterior margin. Viewed laterally, it runs almost horizontally. A denticled median dorsal ridge extends to about middle of carapace and often even somewhat beyond it. Anterior lobe without denticles. Margin of the pseudorostral lobe (Figure 39) finely denticled. Above subrostral angle, which is only slightly extended and not pointed, is a row of small denticles rapidly becoming indistinct toward posterior part.

At posterior margin of last abdominal segment, somewhat on the dorsal side (Figure 43), are 2 spines.

Last article of antennula peduncle (Figure 40) longer than penultimate. Accessory flagellum very short and not reaching much less than midlength of first article of biarticulate main flagellum. Antennula reaches only slightly beyond tip of pseudorostrum.

First pereopod (Figure 41) long. Basis about as long as distal articles combined, excluding dactylus. Carpus is longest of 3 distal articles and propodus is shortest.

Second pereopod (Figure 42) basis somewhat shorter than distal part. Carpus as long as propodus and dactylus combined; propodus somewhat shorter than dactylus.

Uropods (Figure 43) compact. Peduncle about as long as last 2 abdominal segments combined. Endopod about as long as peduncle; distal segment slightly more than 2/3 length of proximal joint. Exopod distinctly longer than endopod. Inner margin of peduncle with a few fine spines, dorsal side with a row of long spines; inner margin of first and second joints of endopod with 6 and 2 spines, respectively.

DESCRIPTION OF ADULT MALE.—Length about 5.5 mm. Pseudorostrum (Figure 44) somewhat shorter and more truncate than in female, but quite long for a male of this genus. Dorsal median row of denticles on carapace completely lacking. Anterior margin of pseudorostrum (Figure 45) slightly denticled above subrostral notch. Subrostral notch broadly rounded; subrostral angle and margin of carapace behind it completely lack denticles.

Main flagellum of antennula (Figure 46) 4-articled; proximal article with group of esthetascs.

Ischium of third pereopod (Figure 47) with 2 long spines close to inner margin, neither particularly stout nor modified in form, and without conspicuous differences from spines on carpus or propodus.

Uropod peduncle (Figure 48) about half as long as last 2 abdominal segments combined. Endopod distinctly longer than peduncle; distal segment only slightly shorter than basipodite. Exopod considerably longer than endopod. Inner margins of peduncle and endopod with abundant and complex armature of fine plumose setae and spines.

MATERIAL EXAMINED.—Woods Hole, Mass., surface, in the evening, 2 May 1888, U.S. Fish. Comm., 1 female, 1 male.

Amityville, Long Island, N.Y., 6 Jul 1938. H. K. Townes, 1 female, 1 male in breeding stage.

Moriches Bay, Long Island, N.Y., H. K. Townes, 42 females and males, among them females in “Brutkleid” and males in breeding stage.

Steamer Fish Hawk Stations in Chesapeake Bay: Sta 8800*, 12.5 m, 3–4, Jul 1920, 2 males; Sta 8803, 10 m, 4 Jul 1920, 10.080/00, 6 females and males; Sta 8804, 12.5 m, 5 Jul 1920, 16.220/00, 2 pulli; Sta 8812*, 12.81 m, 7 Jul 1920, 17.270/00. 1 female, 4 males; Sta 8826*, 45.75 m, 8 Jul 1920, 25.230/00, 5 females (1 adult), 2 males; Sta 8907*, 14.64 m, 6 Dec 1920, 1 male; Sta 8926*, 12.81 m, 9 Dec 1920, salinity 16.780/00, 9 females, 2 males; Sta 8940*, 12.81 m, 24 Jan 1921, 14.720/00, 1 female, 1 male; Sta 8950*, 47.58 m, 26 Jan 1921, 17.700/00, 1 male; Sta 8955*, 12.81 m, 27 Jan 1921, 11.390/00, 1 adult male; Sta 8957, 12.81 m, 27 Jan 1921, 14.250/00, 2 females; Sta 8958*, 20.13 m, 27 Jan 1921, 14.460/00, 1 male; Sta 8961*, 18 m, 28 Mar 1921, 12.990/00, 5 females, 4 males; Sta 8962*, 15 m, 28 Mar 1921, 12.410/00, 1 female, 5 males; Sta 8963*, 9 m, 28 Mar 1921, 9.160/00, numerous specimens, among them adult males, but no adult females; Sta 8968*, 7 m, 29 Mar 1921, 11.840/00, 4 males.

Potomac River at Tall Timbers, Md., 28 Mar 1928, J. E. Benedict, coll., numerous specimens—female and male.

Beaufort, N.C.*, 23 May 1935, from stomach of Penaeus setiferus female, G. Gubsell, coll., 1 male.

One mile inside of May River, S.C.*, 17 Jan 1891, Steamer Fish Hawk, 1 female, 1 male.

Cape Cod to Cape Hatteras

Found in brackish waters in the sublittoral zone, over mud substrate.