Hemus magalae, Windsor, Amanda M. & Felder, Darryl L., 2011

Windsor, Amanda M. & Felder, Darryl L., 2011, A new species of Hemus (Majoidea: Majidae: Mithracinae) from the Pacific coast of Panamá, with a key to the genus, Zootaxa 2799, pp. 63-68 : 64-66

Hemus magalae n. sp.

( Figures 1 , 2 D)

Material examined. Male holotype carapace length 6.47 mm, carapace width 5 mm at widest point ( USNM 1149374). Islas de las Perlas, Pacific Ocean coast of Panamá (08°10’8.00”N; 78°52’6.00”W). R/V Urraca, station 2, dredge over rocks at 27 m depth, 23 February 2007.

Diagnosis. Carapace without lateral teeth; cardiac prominence not elevated above gastric regions; orbits incomplete, unprotected above. Rostrum broad, tips widely separated, minutely developed to either side of broad terminal sinus. Antenna first movable article quadrate, slightly longer than broad. Meri of ambulatory pereopods broad, anterior and posterior margins cristate, concave above, margins strongly denticulate.

Description. Carapace widest at mesobranchial region, little constricted across hepatic region; gastric and cardiac regions with patches of small granules, both equally elevated, mesobranchial region relatively less elevated; hepatic region depressed, mesogastric region bearing cluster of small, hooked hairs; margin of carapace with ridge of granules and fine setae, eight tufts of long setae arranged symmetrically near posterior carapace margin; orbits incomplete, unarmed. Rostrum broad, trapezoidal with ridge of minute granules along lateral border, anterior tips widely separated, minutely developed to either side of broad, shallow terminal sinus. Antenna with fused basal article bearing large granule visible in dorsal view; first movable article longer than broad, quadrate form derived from strong angular anteromesial, and posterolateral flanges, anterior margin arched, margins denticulate.

Chelipeds slender, chelae distally bent towards carapace front, lacking gape when fingers closed. Both first ambulatory pereopods missing in holotype, remaining pereopods posteriorly decreasing in size; merus broad, dentate anterior and posterior margins strongly cristate, continuous at rounded juncture proximally, marginal denticles rounded, anterior larger, tending to flattened lobes, dorsal surface broadly concave overall, weak longitudinal elevation within concavity along article midline, joining setose tubercle distally; scattered tufts of long setae along and below margins; carpus bearing short posterior marginal flange; anterior and posterior margins of carpus and propodus with regularly spaced line of rounded denticles; propodus and dactylus with well-developed locking articulation between articles; dactylus curved strongly near acute, corneous tip.

Male abdomen with six free segments and telson, first two segments with sparse, long setae along finely denticulate lateral margins; two to four sets of granules on ventral surface that sometimes overlap proceeding segment, third segment through telson finely granulate, setose; terminal segment broadly subtriangular to rhomboidal, subtruncate terminally. Entire lateral margin of abdomen fringed with short setae. First gonopod stout with minute spinules at tip, sparse setae along length.

Etymology. The epithet magalae is an arbitrary euphonic derivation of the Latin word for pearl (margarita) to indicate that the holotype was collected from Islas de las Perlas (“Pearl Islands”), Panamá. It is used as a noun in apposition.

Remarks. This species may be the same as the Hemus sp. of Hendrickx (1993, 1999), which apparently remains undescribed. Compared to the illustrations by Hendrickx (1999, pg. 165, fig. 94) and Garth (1958, pg. 550 pl. X), the first movable article of the antenna of H. magalae is broader and more quadrate than that of H. finneganae , while the carapace is comparatively flatter and less sculptured than in either H. finneganae or H. analogous . The first gonopod is heavier than in any of the other three species ( Fig. 2 A-D). As in H. analogus , the gonopod of H. magalae lacks the characteristic double lateral flange of H. finneganae described and illustrated by Garth (1958, pg. 423, pl. Y, fig. 7).

Figures

FIGURE 1. Hemus magalae n. sp. (USNM 1149374). A) Dorsal view of carapace and appendages, B) male abdomen, C) third maxilliped, D) ventral surface of basal antennal article, E) lateral view of merus of first ambulatory pereopod, F) lateral view of carapace, G) left first gonopod, abdominal view. All scale bars = 1 mm.

FIGURE 2. Gonopods from A) Hemus analogus Rathbun, 1898, B) H. cristulipes A. Milne-Edwards, 1875 ULLZ 5783, C) H. finneganae Garth, 1958, D) H. magalae n. sp. (USNM 1149374). A, C re-drawn from Garth, 1958. Scale bars = 1 mm.