Halmyrapseudes cooperi (Brown, 1954)

Kakui, Keiichi & Angsupanich, Saowapa, 2013, Description of three species of Halmyrapseudes (Crustacea: Tanaidacea: Parapseudidae), with a discussion of biogeography, Zootaxa 3736 (4), pp. 345-367 : 358-364

Halmyrapseudes cooperi (Brown, 1954)

Figures 8–11

Apseudes cooperi Brown, 1954 , 939–942, figs. 1–11.

Apseudes cooperi: Brown 1956 , 705; Băcescu & Guţu 1974, 100; Băcescu & Guţu 1975, 112; Bamber et al. 2002, 296. Apseudes digitalis Brown, 1956 , 707–709, fig. 1–8.

Apseudes digitalis: Băcescu & Guţu 1974 , 100; Băcescu & Guţu 1975, 112. Halmyrapseudes digitalis: Bamber et al. 2002 , 295, 296; Guţu 2008, 51. Halmyrapseudes cooperi: Guţu 2008 , 51.

Material examined. One subadult male (SAM A19360.1, BL 3.08, CW 0.59, 5 slides and 1 vial). Labeled “ APSEUDES COOPERI BROWN, 1954 /Station No. HAV 20D/DATE 15·I·1950/LOC. BASHEE R. 2 1/ 2 mi. FROM MOUTH OPP. FIRTH KRANTZ, THE HAVEN/GEAR HAND NETTING IN REEDS/PRES 70% EtOH/ COLL UCT ECOLOGICAL SURVEY/DET A C BROWN”. One subadult male (SAM A19361.1, BL 4.62, CW 0.85, 5 slides and 1 vial). Labelled “ APSEUDES DIGITALIS BROWN, 1956 /Station No. RHB 127H/DATE 26·I·1951/LOC. 2ND MANGROVE CLUMP±80yds FROM MOUTH OF UMSINGASI R. RICHARDS BAY/ GEAR HAND NETTING/PRES 70% EtOH/COLL UCT ECOLOGICAL SURVEY/DET A C BROWN”. One preparatory female (SAM A19361.2, BL 4.41, CW 0.82, 3 slides and 1 vial): same collection data as for SAM 19361.1. One female (SAM A19361.3, BL 2.96, CW 0.59, 3 slides and 1 vial): same collection data as for SAM 19361.1.

Diagnosis. Lacinia mobilis with 3 teeth. Mandibular palp article 2 without dorsal simple setae. Pereopod 1 carpus with 4,2, 2,2 or 4,3 ventral simple setae proximal to each spiniform seta.

Redescription of male (SAM A19360.1; partly based on SAM A19361.1). Body ( Fig. 8 A) dorsoventrally flattened, 5.2 times as long as wide. Cephalothorax 0.21 times BL, as long as wide, with one pair of lateral simple setae. Posterior region with dorsal groove. Eyes not confirmed; without ommatidia. Rostrum rounded. Pereonites and pleon typical for genus.

Antennule ( Fig. 8 B) 2.39 times as long as carapace. Article 1 0.77 times as long as remaining articles and outer flagellum combined, with four outer and three inner simple setae, and several minute simple setae and plumose sensory setae. Article 2 0.43 times as long as article 1, with six outer, two mid-inner, and three inner distal simple setae, and five plumose sensory setae. Article 3 0.37 times as long as article 2, with two outer, one mid-inner, and three inner simple setae. Article 4 with one plumose sensory seta, and two simple setae and one plumose sensory seta at insertion of inner flagellum. Outer flagellum with eight articles; four terminal articles with three, zero, one, five simple setae (from proximal to distal), respectively; second and fourth articles from the end with one aesthetasc; distal article with one plumose sensory seta; the other articles each with simple setae as illustrated. Inner flagellum with two articles; article 1 with one plumose sensory seta; article 2 with three simple setae and one plumose sensory seta.

Antenna ( Fig. 8 C) 0.44 times as long as antennule, with nine articles. Article 1 with inner distal lobe bearing four simple setae. Article 2 with one outer and one inner simple setae. Article 3 with three inner simple setae. Article 4 with one outer and one inner simple setae, and two plumose sensory setae. Article 5 with two outer and four inner simple setae, and three plumose sensory setae. Articles 1–5 combined 0.72 times as long as remaining articles. Articles 6–8 with simple setae as illustrated. Article 9 with five simple setae. Squama with three simple setae.

Labrum ( Fig. 8 D) bipartite, with fine setae as illustrated; distal margin slightly convex. Mandibles ( Figs. 8 E–G, 10B, C) with molar process well developed, bearing distal row of denticles. Left mandible ( Figs. 8 E, G, 10B) incisor with four teeth; setiferous lobe with several (ca. 12) complex setae; lacinia mobilis with three teeth ( Fig. 10 B; SAM A19361.1). Right mandible ( Figs. 8 F, 10C) incisor with four teeth; setiferous lobe with ca. eight setae ( Fig. 10 C; SAM A19361.1). Palp ( Fig. 8 E) with three articles; article 1 with two ventral simple setae; article 2 with 11 ventral simple setae; article 3 with eight ventral pinnate setae. Labium ( Fig. 8 H) with lobe bearing outer serration and ventral setation. Palp setulated, with two multifurcate setae. Maxillule ( Fig. 8 I, i1) with palp bearing two subdistal and one distal setae. Outer endite with 11 distal spiniform setae (some spiniform setae with minute teeth: Fig. 8 i1), two subdistal setae, and outer and inner clumps of simple setae. Inner endite curving inward, with four distal setulate setae, several outer and inner simple setae, and one outer process. Maxilla ( Fig. 8 J, j1, 2) with inner lobe of fixed endite bearing 11 setae and two biserrate setae; outer lobe of fixed endite with six simple setae, two pinnate setae, one upswept pinnate seta, one setulate seta, one branch-shaped seta ( Fig. 8 j2), and three multifurcate spiniform setae; inner lobe of movable endite ( Fig. 8 j1) with ca. 10 simple setae and three combshaped setae; outer lobe of movable endite with two subdistal and five distal comb-shaped setae. Maxilliped ( Fig. 8 K, k1) with coxa. Basis with four simple setae. Endite with two simple setae, eight complex spiniform setae, and setulation in distal region; outer region with serration; inner region with six basally setulate setae and four coupling hooks. Palp article 1 with one ventral and one outer distal simple setae; article 2 with one outer simple seta, and five inner ventral and 21 inner simple setae; article 3 with 12 narrower and three thicker simple setae in inner region; article 4 with three subdistal simple setae and four distal pinnate spiniform setae. Epignath ( Fig. 8 L) cupshaped, with setulate terminal seta.

Cheliped ( Fig. 9 A) with coxa bearing one simple seta. Basis ca. 1.4 times as long as wide, with several small and one inner distal simple setae; ventral region with two middle and five subdistal simple setae. Merus with three outer and one inner simple setae in dorsal region; ventral region with one subdistal and three inner distal simple setae. Carpus twice as long as wide, with 11 outer and 12 inner simple setae in dorsal region; ventral region with four marginal and two outer simple setae, and one inner semicircular expansion. Propodal palm with two outer, two inner, two ventral, and one inner ventral simple setae; insertion of dactylus with six simple setae and one serrate seta. Fixed finger with three ventral simple setae; cutting surface with seven outer and one inner simple setae and seven biserrate lamellar setae. Dactylus longer than fixed finger, with one simple seta and two pinnate setae in inner region; cutting surface with six narrow serrate setae and three fine setae. Exopod with three articles; distal article with four plumose setae.

Pereopod 1 ( Fig. 9 B) 0.36 times BL, longest of pereopods. Coxa with five simple setae. Basis 0.36 times total pereopod 1 length, 1.92 times as long as wide, with one long and several minute simple setae in dorsal region; ventral margin with four simple setae; distal region with five simple setae and two short setae. Ischium wider than long, with one short and three long simple setae. Merus widening distally, with four dorsal, one outer, seven inner ventral, nine ventral, and one ventrodistal short simple setae, and one inner dorsal and one ventral spiniform setae. Carpus slightly shorter than merus, expanding dorsodistally; dorsal region with row of simple setae (consisting of 17 simple setae), three outer simple setae, and one spiniform seta; ventral region with one inner proximal, two inner distal, one outer distal, and one outer simple setae, two spiniform setae, and four and two simple setae proximal to each spiniform seta. Propodus slightly shorter than carpus, with seven simple setae, one plumose sensory seta, and two spiniform setae in dorsal region; ventral region with three outer and one distal simple setae, one inner distal serrate seta, three spiniform setae, and six, three, three simple setae proximal to each spiniform seta. Dactylus together with unguis shorter than propodus; dactylus with one mid-dorsal simple seta and one ventral serration; unguis 0.4 times dactylus length. Exopod with three articles; distal article with five plumose setae.

Pereopod 2 ( Fig. 9 C) 0.82 times pereopod 1 length. Coxa with one simple seta. Basis 2.4 times as long as wide, with three ventral and six ventrodistal simple setae, several minute dorsal simple setae, and several plumose sensory setae. Ischium with one short and three long simple setae. Merus with one outer distal, six ventral, and one ventrodistal simple setae, one inner dorsodistal seta, and one ventrodistal and two outer conical setae. Carpus as long as merus, expanding dorsodistally; dorsal region with row of simple setae (consisting of eight simple setae), and five conical setae; ventral region with seven ventral simple setae and three conical setae. Propodus longer than carpus, with six simple setae, one plumose sensory seta, and one conical seta in dorsal region; ventral region with one inner distal serrate seta, one outer and two ventral conical setae, and three, three simple setae proximal to each conical seta. Dactylus together with unguis as long as propodus; dactylus with one mid-dorsal simple seta.

Pereopod 3 ( Fig. 9 D) shorter than but otherwise similar to pereopod 2, except that numbers of simple setae, plumose sensory setae, and conical setae on each segment differ slightly as illustrated.

Pereopod 4 ( Fig. 9 E) with coxa bearing one simple seta. Basis with two middle and three distal simple setae and one plumose sensory seta in ventral region; dorsoproximal region with three plumose sensory setae. Ischium like that of pereopod 3. Merus with five outer and three inner simple setae in ventral region; dorsodistal region with one seta. Carpus longer than merus; outer region with seven simple setae and three conical setae; inner region with seven simple setae and four conical setae. Propodus shorter than carpus, with five ventral simple setae, one dorsal plumose sensory seta, two distal pinnate setae, and distal row of serrate setae (consist of ca. 13). Dactylus together with unguis far shorter than on other pereopods, but longer than serrate setae on propodus, with one mid-dorsal and two ventrodistal fine setae.

Pereopod 5 ( Fig. 9 F) with coxa to carpus similar to those of pereopod 4, except that number of simple setae and conical setae on each segment differ slightly as illustrated. Propodus as long as carpus, with one plumose sensory seta; ventral region with two simple setae, and two ventral and one ventrosubdistal conical setae; distal region with seven long and one short simple setae, one inner setulate (ca. twice as long as serrate seta: Fig. 9 f1) seta, and one inner serrate seta. Dactylus together with unguis like that of pereopod 2.

Pereopod 6 ( Fig. 9 G) with coxa naked. Basis with three plumose sensory setae, dorsal and ventral setal rows consisting of 12 and 5 plumose setae, respectively, and two ventrodistal plumose setae. Ischium with one short and two long simple setae. Merus with four ventral and one ventrodistal simple setae, and three outer and five dorsal plumose setae. Carpus longer than merus, with seven long and one short ventral, and one outer distal simple setae, one ventrodistal spiniform seta, three outer conical setae, and six dorsal and two outer distal plumose setae. Propodus slightly shorter than carpus, with one distal and one outer simple setae, one ventroproximal and two distal conical setae, two distal setulate setae, five dorsodistal serrate setae bearing short teeth, and two distal and 14 (one of them longer than others) ventral serrate setae. Dactylus togehter with unguis like that of pereopod 5.

Pleopods ( Fig. 9 H) biramous, all similar in shape. Basal article as long as wide, with three inner plumose setae. Exopod slightly widening distally, with one mid-inner, one outer proximal, 16 outer plumose setae. Endopod larger than exopod, oval, with 18 plumose setae and one mid-inner distally hooked plumose seta.

Uropod ( Fig. 9 I) with basal article bearing six distal simple setae and two distal plumose setae. Exopod with four articles; article 1 with one seta; article 4 with four simple setae. Endopod broken.

Redescription of female (SAM A19361.2). Body generally similar to that of male, except genital cone lacking.

Antennule is 1.44 times as long as carapace. Article 1 half as long as remaining articles and outer flagellum combined. Article 2 is 0.43 times as long as article 1. Article 3 is 0.48 times as long as article 2. Setation on articles 1–4 as on male, except one mid-inner simple seta on article 2 in female. Outer flagellum with seven articles; four terminal articles similar to those of male, except aesthetascs only on penultimate article in female; other articles similar to those of male. Inner flagellum like that of male.

Antenna is 0.51 times as long as antennule, with 10 articles, as in male.

Most mouthparts not studied, except for left mandible. Left mandible incisor with four teeth; setiferous lobe with ca. eight complex setae; lacinia mobilis with three teeth. Palp with three articles; article 1 with two ventral simple setae; article 2 with 15 ventral simple setae; article 3 with nine ventral pinnate setae.

Cheliped ( Fig. 10 A) with basis 1.67 times as long as wide, with several short, two inner proximal, and two inner distal simple setae; ventral region with one middle and five subdistal simple setae. Merus with four outer and one inner dorsal simple setae; ventral region with three middle, one subdistal, and five inner distal simple setae. Carpus with 13 outer and 14 inner simple setae in dorsal region; ventral region with seven marginal and three outer simple setae. Propodal palm with one dorsal, two outer, two inner dorsal, and one inner ventral simple setae; insertion of dactylus with seven simple setae and one serrate seta. Fixed finger with five ventral simple setae; cutting surface with 12 outer and one inner simple setae and 11 biserrate lamellar setae. Dactylus longer than fixed finger, with one simple seta and two pinnate setae in inner region; cutting surface with eight narrow serrate setae and thee fine setae. Exopod like that of male.

Pereopods 1–6 and pleopods similar to those of male, except number of setae is slightly different. Uropod with basal article and exopod similar to those of male; endopod similar to that of H. gutui , with serially repeated articles bearing simple setae and plumose sensory setae.

Variation and remarks. Numbers of simple setae in the ventral region of the pereopod 1 propodus and carpus are variable: the propodus has 6,3,3 and 5,5,4 simple setae in males (SAM A19360.1 and 19361.1, respectively), and 4,4,4 and 3,3,3 simple setae in females (A19361.2 and 19361.3, respectively); the carpus has two (A19361.3) or four (in the other three) simple setae, proximal to the more proximal of the two ventral spiniform setae. Although the cheliped in A19360.1 lacks the inner proximal simple setae on the basis and the mid-ventral simple setae on the merus, the other three bear these setae. One of three outer ventral simple setae in the chelipedal carpus and one dorsal simple seta on the propodal palm only appear in A19361.2. One ventrosubdistal conical seta on the pereopod 5 propodus in A19360.1 is spiniform in the other three. Only in A19361.1 does the pleopodal basal article bear four plumose setae. The numbers of simple setae and conical setae in most positions, and of plumose setae on the pereopod 6 and the pleopodal rami, are variable.

The number of articles in the antenna and the outer flagellum of antennule is variable: Antenna has nine (A19360.1, 19361.3) or 10 (A19361.1, 19361.2) articles (articles 1–5 are similar in all antennae); the antennule flagellum has six or seven articles in females and eight or 10 in males.

In addition to the other dimorphic characters (see the variation section for H. gutui ), the following characters in each sex may be consistently dimorphic: the pereopod 1 basis has two ventrodistal short simple setae in males, one in females; the pereopod 4 basis bears two mid-ventral simple setae in males, none in females; the article 2 of the antennule has two mid-inner simple setae in males, one in females.

In his descriptions, Brown (1954, 1956) noted “eyes small” for H. cooperi and “eyes absent” for H. digitalis (both then placed in Apseudes ). We detected no ommatidia in three specimens of H. cooperi , but observed a few, colourless ommatidium-like structures in one female (A19361.3) ( Fig. 11 ). This raises the possibility that our samples include both species. However, as described above, the specimens we attribute to H. cooperi share many other detailed characters, and we attribute the apparent lack of ommatidia as a possible artifact due to length of preservation, poor fixation, etc.

Antennule in one male (A19361.1) bears a shallow groove on the part of the article 4 that connects to the inner flagellum ( Fig. 10 D: arrowhead). This looks like a trace or rudiment of an articulation. At this point, we cannot judge whether the groove becomes an articulation, leading us retain this species in Halmyrapseudes .

Figures

FIGURE 11. Eye condition in Halmyrapseudes cooperi (Brown, 1954). A, carapace of male (SAM A 19360.1) without any ommatidia, dorsal view; B, carapace of female (SAM A 19361.3) with some ommatidium-like structures (arrowheads). Both specimens are after dissection. Scale bar: 0.1 mm.