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Description of Male.
Length 3 mm.; depth ½ mm.; width 1 mm. Eyelobes rounded, rostrum small, not extending past eyelobes.
Antennae. First: Length 1 ¾ mm.; flagellum of 8 segments, a little longer than 1st segment of peduncle, minute end segment has terminal setae, other segments have a few distal setae, are longer than wide; last 2 or 3 have a long flaccid sensory seta distally. Peduncle, 1st segment width ⅖ length, margins slightly convex, setose; inferior margin has 4 stout spines along length, numerous long setae; 2nd segment slightly shorter than 1st, width ⅕ length; margins setose, especially superior; 3rd segment narrower, ⅖ length 2nd, a few setae medially and distally. Second: Length 2 ¼ mm.; peduncle stout, spine on gland-cone; 3rd segment, width twice length, a few setae inferiorly and on surface; 4th very stout, width nearly ½ length, length more than 4 times 3rd; inferodistal angle produced to long
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Text-Fig. 3.
Corophium acutum Chevreux. 26—Antenna 1, ♀. 27—Antenna 2, ♀. 28—Gnathopod 1, ♂. 29—Gnathopod 2, ♀. 30—Peraeopod 4, ♀. 31—Epimeral plate 1. 32—Epimeral plate 2. 33—Epimeral plate 3. 34—Urosome, ♂. Corophium acherusicum Costa. 35—Antenna 1, ♀. 36—Antenna 2, ♀. 37—Gnathopod 1, ♀. 38—Gnathopod 2, ♀. 39—Urosome, ♀.
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slender tooth, above it on end margin a smaller tooth; 2 small strong spines on inferior surface; single and paired setae on margins and surface; 5th segment, length ¾ 4th, width less than ¼ length, long setae in groups on margins especially inferiorly; inferior margin produced downwards proximally to small tooth; distal margin produced as strong lobe ½ along 1st flagellar segment. Flagellum 1st segment ½ length 5th peduncle segment, narrower, small tufts of setae on margins; 2nd segment ½ length 1st, strongly setose distally; 3rd segment very small, setose, 2 apical spines.
Gnathopods. First: Subchelate, much as in C. sextonae, fewer palmar spines, palm straighter, distal angle more clearly defined; dactylos reaching a little past end of palm. Second: As in C. sextonae but dactylos quadridentate.
Peraeopods. Not greatly different from C. sextonae; small variations in proportions and spination; Pr. 4 carpus has rows of 4 and 5 stout hooked spines.
Urosome. Segments fused, uropods 1 and 2 attached ventrally; lateral margins of urosome without notches, with fringe of fine bristles, several marginal setae.
Uropods. All reaching about same distance. First: Rami subequal, ½ peduncle length; outer distal angle produced downwards a little in blunt tooth, peduncle outer margin has about 6 stout seta-tipped spines, end margin produced medially to blunt triangular tooth more than ⅓ along between rami; rami relatively stout; outer has 4 seta-tipped spines on outer margin, 2 short end setae, outer distal angle produced to short stout sharp point; slightly convex inner margin naked; inner ramus outer margin has 3 seta-tipped spines, distal angle acute, inside it on end margin a small and a large spine; straight inner margin naked. Second: Length ½ 1st; inner ramus ½ peduncle length, outer ¾ peduncle length; peduncle width ½ lenth; outer margin like that of outer ramus with a few setae and fringe of fine bristles. Outer ramus margins slightly convex, outer distal angle acute, short stout spine on inner distal angle. Inner margins of both rami and outer margin o inner ramus naked; inner ramus margins straight, end margin truncate forming acute outer angle, strong spine on inner distal angle. Third: Peduncle about ¾ ramus length, slightly convex outer margin has fringe of fine bristles; ramus distally convex, about 10 long setae and fringe of fine bristles on end and outer margin. Telson: Subtriangular; reaching a little past uropod 3 peduncle; 2 rows each of about 3 very short spines on surface distally and almost parallel with outer margins; short seta on outer proximal surface.