Leptochela bermudensis Gurney 1939

Leptochela (Leptochela) bermudensis Gurney

?Leptochela carinata Ortmann, 1893:41 [part, not pl. 4: fig. 1].

Leptochela carinata.—Schmitt, 1924:69.—Gurney, 1936:786, pl. 1: figs. 1–5, pl. 2: figs. 7–12, pl. 3: figs. 14–18, pl. 4: figs. 19–30, pl. 5: figs. 33–34. [Not L. carinata Ortmann, 1893, pl. 4: fig. 1.]

Leptochela bermudensis Gurney, 1939:427, figs. 1–10.—Chace, 1940:131, fig. 10—Holhuis, 1955: fig. 15b.—Springer and Bullis, 1956:10.—Chace, 1972:16.

DIAGNOSIS.—Rostrum with dorsal margin usually straight or concave, occasionally sinuous or even convex throughout. Carapace with 3 longitudinal dorsal ridges in breeding females only. Orbital margin entire, not serrate, without mesially directed tooth on ventral portion; suborbital angle rounded, rarely with minute denticle. Fifth abdominal somite entire, without dorsal elevations or posterior tooth. Telson with 1 pair of dorsolateral spines in addition to anterior mesial pair; posterior margin with pair (rarely fused) of minute mesial spines in addition to usual 5 pairs of prominent spines. Antennal scale little more than ½ as long as carapace. First pereopod with 11 to 30 spines on opposable margin of movable finger. Second pereopod with 18 to 37 spines on opposable margin of movable finger. Third pereopod with exopod not nearly reaching distal end of ischium. Endopod of 1st pleopod of male flared distolaterally. Appendix masculina, not including spines, distinctly overreaching appendix interna. Maximum carapace length 4.5 mm.

DESCRIPTION.—Rostrum (Figure 5a) with dorsal margin somewhat variable, usually nearly straight or concave, occasionally sinuous or even slightly convex from base to tip, rarely overreaching basal segment of antennular peduncle. Carapace with median dorsal carina on anterior 1/5 to ½ of length but without paired dorsolateral carinae in males and nonbreeding females, dorsally tricarinate over most of length in breeding females. Orbital margin (Figure 5b) entire, not serrate, ventral portion without mesially directed tooth; suborbital angle rounded, rarely with minute marginal denticle.

Abdominal terga (Figure 5c) regularly rounded on 3 anterior somites and all but posterior part of 4th. Fifth somite bluntly, sometimes obscurely, carinate dorsally, entire, without dorsal prominences of any kind and without posterodorsal tooth. Sixth somite nearly twice as long as high, with usual transverse swelling and carina near anterior end of dorsal surface, long slender spine on ventrolateral surface and usually distinct, rarely obscure, acute tooth (Figure 5d) on posterodorsal margin of posterolateral lobe. Telson (Figure 5e), not including posterior spines, about 1.6 times as long as 6th somite, little more than 3 times as long as wide, armed with 1 pair of dorsolateral spines at about midlength, in addition to anterior mesial pair; posterior margin (Figure 5f) bearing pair (rarely fused) of minute mesial spines (Figure 5g) between bases of mesial pair of usual 5 pairs of prominent spines.

Eye (Figure 5b) with papilla on mesial surface of stalk proximal to cornea, cornea little if at all wider than stalk.

Antennular peduncle (Figure 5h) with stylocerite reaching nearly as far as distolateral margin of basal segment; 2nd segment longer than distal segment in mesial aspect but distinctly shorter in dorsal aspect.

Antennal scale (Figure 5i) little more than ½as long as carapace, 2.8 to 3.7 times as long as wide, lateral margin slightly sinuous, blade forming rather distinct shoulder at base of distal tooth. Distal segments of antennal peduncle about 2/3 as wide as scale, not reaching midlength of scale.

Mouthparts as illustrated (Figure 6a–f). Third maxilliped (Figure 6f) rarely overreaching antennal scale, distal segment about 2/5 as long as penultimate segment.

First pereopod (Figure 6g) overreaching antennal scale by slightly more or slightly less than length of fingers; fingers 1.2 to 1.7 times as long as palm; dactyl (Figure 6h) armed with 11 to 30 spines on opposable margin. Second pereopod (Figure 6i) rarely overreaching antennal scale by as much as length of fingers; fingers 1.7 to 2.2 times as long as palm; dactyl (Figure 6j) armed with 18 to 37 spines on opposable margin. Third pereopod (Figure 6k) overreaching extreme anterior margin of carapace by about ½ length of dactyl; exopod falling considerably short of distal end of ischium; ischium armed with row of about 6 slender spines near extensor margin and 4 subequally spaced stouter spines on lateral surface; merus with 5 blunt spines on lateral surface; dactyl shorter than propodus. Fourth pereopod (Figure 6f) reaching to about midlength of ischium of 2nd pereopod when both extended anteriorly; dactyl usually shorter than propodus. Fifth pereopod (Figure 6m) similar to and little shorter than 4th, reaching nearly to midlength of ischium of 2nd pereopod when both extended anteriorly; dactyl shorter than propodus.

Endopod of 1st pleopod of male (Figure 7a,b) with lateral margin distinctly flared distally. Appendix masculina (Figure 7c,d) bearing 9 long spines, far overreaching appendix interna, without including spines. Lateral branch of uropod (Figure 5e) armed with 8 to 15 movable spines, in addition to setae.

SIZE.—Carapace lengths of males, 2.1–3.0 mm; of nonbreeding females, 2.1–3.0 mm; of nonovigerous breeding female, 2.7 mm; of ovigerous females, 2.4–3.0 mm; of juveniles, 1.6–1.9 mm. In contrast, Chace (1940) recorded males with a maximum carapace length of 4.5 mm and ovigerous females of 3.2 mm from off Bermuda.

MATERIAL.—GULF OF MEXICO. Cayos Arcas, Bahia de Campeche; 18 m; 11 December 1952; from bonefish stomach; Oregon: 1 (2.2) 2 juv. (1.6, 1.8). Cayos Arcas, Bahia de Campeche; 20°12′N, 91°W; 11 m; 18 July 1957; traplift net with light; Oregon Sta. 1848: 2 juv. (1.6, 1.9).

PUERTO RICO. Playa de Fajardo; 23 February 1933: 8-foot circular net under cargo light; Johnson-Smithsonian Deep-sea Expedition: 1 (2.5). Cayo Icacos; 24 February 1933; 8-foot circular net with cargo light and submarine light; Johnson-Smithsonian Deep-sea Expedition: 9 (2.1– 2.5) 2 (2.1–2.4). Canal de Luis Peña, Isla de Culebra; 25 February 1933; 8-foot circular net under cargo light; Johnson-Smithsonian Deep-sea Expedition: 3 (2.5–2.5). Same; 3-foot net towed from port launch: 21 (2.3–2.6).

VIRGIN ISLANDS. Brewers Bay, Saint Thomas; 1 March 1933; 8-foot circular net under cargo light; Johnson-Smithsonian Deep-sea Expedition: 10 3 (2.4–2.7) 5 (2.6– 3.0).

LEEWARD ISLANDS. Off Oyster Pond Landing, Barbuda; 5 April 1956; 7:00–8:30 p.m.; light over side at anchorage in 5.5 m; Smithsonian-Bredin Caribbean Expeditions Sta. 84–56: 2 (3.0) 1 ovig. (3.0). Prince Rupert Bay, Dominica: 28 March 1956; 8:45–9:30 p.m.; light over side at anchorage in 7 m; Smithsonian-Bredin Caribbean Expeditions Sta. 64–56: 1 (2.5).

WINDWARD ISLANDS. West by north of telegraph station, Barbados, little more than ½, mile off; 55–119 m; rocks and sand; 5 June 1918; University of Iowa Barbados-Antigua Expedition Sta. 79: 1 ovig.. (2.5). Off Lazaretto, Barbados; 37 m; bottom rough; 6 June 1918; University of Iowa Barbados-Antigua Expedition Sta. 87: 1 ovig. (2.4).

HABITAT.—Although most of the specimens listed above were taken in relatively shallow water (5.5–18 m), the type-series (Gurney, 1939) and material subsequently collected off Bermuda (Chace, 1940) were taken in the open ocean between the surface and 1200m.

Seven of the 11 lots currently available to me were obtained at night under a light, yet there is some evidence that L. (L.) bermudensis may be less strongly photopositive than is L. (L.) serratorbita, which is sympatric with it over much of its range. At five stations where a light was used and both species were collected, L. (L.) serratorbita outnumbered L. (L.) bermudensis 676 to 33. At only one station (Cayo Icacos, Puerto Rico) was the latter more numerous (11 to 8), while at two stations (Playa de Fajardo, Puerto Rico, and Barbuda) L. (L.) serratorbita outnumbered L. (L.) bermudensis by about 150 to 1. On the other hand, the lot collected with a townet in Canal de Luis Peña, Puerto Rico, contained 21 L. (L.) bermudensis and only 4 L. (L.) serratorbita, whereas a light station at that locality on the same night produced 27 L. (L.) serratorbita and only 3 L. (L.) bermudensis. Such evidence must be treated with caution, however, because of the probability that swarming occurs in both species.

TYPE-LOCALITY.—Seven miles south of Bermuda between 1000 meters and the surface.

DISTRIBUTION.—Bermuda to Barbados and southwestern Gulf of Mexico, between 1000 meters or more and the surface in the open ocean and in inshore depths as shallow as 5.5 meters.