Notopoma africana, Lowry & Berents, 1996

Lowry, J. K. & Berents, Penelope B., 1996, The Ericthonius group, a new perpective on an old problem (Crustacea: Amphipoda: Corophioidea), Records of the Australian Museum 48 (1), pp. 75-109 : 91-95

Notopoma africana n.sp.

Figs 9-12

Type data. HOLOTYPE, male, 2.48 mm, SAM A15547 ; PARATYPE, female, 3.56 mm, SAM A41200 ; 14 PARATYPES, 7 males, 7 females, SAM A41201 ; 4 PARATYPES, 2 males, 2 females, AM P40663 ; south-east of St. Lucia, South Africa, 28°31.7'S 32°34.0'E, 680 m, biological dredge, RV Meiring Naude, 24 May 1976, stn SM103 .

Material described. Based on holotype male, 2.48 mm; dimorphic characters based on paratype female, 3.56 mm.

Diagnosis. Antennae: long, slender. Mandible: palp article 2 long, slender, length 2.8 x breadth, article 3 slender, blade-like. Maxilla 1: outer plate with 7 setal-teeth. Gnathopod 2: male propodus very broad, sightly curved, length 1.7 x width. Peraeopod 7: dactylus with two accessory hoods. Pleopod 2: biramous. Pleopod 3: small, uniramous.

Description. Head: rostrum short, curved down, apically acute, length 0.29 x head; lateral cephalic lobe well developed, ventral corner rounded, subocular margin deeply recessed, anteroventral corner subquadrate, ventral margin horizontal, posterior margin vertical. Antenna 1: long, 0.53 x body length, peduncle with tiny scales; peduncular article 1 produced dorsodistally and dorsomedially, dorsodistal projection 0.1 along article 2, length 1.1 x peduncular article 3; accessory flagellum absent; flagellum long, 4-articulate (female 5), aesthetascs present along ventral margin, article 1 long, 2 x article 2. Antenna 2: subequal in length to antenna 1; peduncle without scales; flagellum 5-articulate (female 6), article 1 long, 2.3 x article 2.

Epistome and upper lip: fused, produced, subacute. Mandible: left and right incisors each with 5 cusps; left lacinia mobilis with 4 cusps, right with 1 large and 1 small cusp and minutely serrate margin; left accessory setal row with 3 pappose robust setae (damaged on holotype, 3 on paratype male), with 3 intermediate plumose setae (damaged on holotype, 3 on paratype male), right accessory setal row with? pappose robust setae, with 2 intermediate plumose setae; molar triturating, molar flake only on right side, molar seta; only on left side; palp article 2 long, slender, length 2.8 x breadth, 1 x article 3, with 1 proximal and 1 distal A2-setae, 4 submarginal B2.,.setae and 2 D2-setae along posterior margin; article 3 slender, blade-like, long, 3.4 x breadth, with 3 proximal A3-setae, 2 submarginal A3- and 2 submarginal B3-setae, and 7 E3-setae. Maxilla 1: inner plate small, with 1 simple apical seta; outer plate with 7 setal-teeth; right and left palps each with 3 terminal robust setae, flag seta present on distolateral corner, right and left palps each with 1 subterminal setae. Maxilla 2: not known. Maxilliped: inner plate subrectangular with 3 nodular robust setae, with 1 subterminal seta on medial corner, oblique setal row with 6 plumose setae; outer plate with 3 apical plumose setae, and 2-3 apicomedial robust. setae; palp article 2, length 2.8 x breadth, article 3, length 1.7 x breadth.

Peraeonite 5: male, length 1 x breadth, female, length 1.3 x breadth. Gnathopod 1: subchelate; coxa not fused to peraeonite 1 in male or female, length 1.2 x depth, without anteroventral lobe; basis in male with sparse setae along anterior margin, in female with sparse setae along anterior margin, without robust setae along anterior margin; carpus length 1.6 x depth with setose posterior lobe, anterior margin without setae in male and female; propodus length 1.7 x depth, with 4 rows of anteromedial setae; palm extremely,acute, sparsely setose, with barbed robust setae. Gnathopod 2: carpochelate in male, subchelate in female; coxa not fused to peraeonite 2 in male or female, length 1.3 x depth, without anteroventral lobe; basis shQrt, broad, length 1.1 x breadth; carpus massive, long, broad, length 1.1 x breadth, posterior margin without tooth; palm transverse, palm narrowly excavate, anterodistal tooth small, located distal to articulation with propodus, posterodistal tooth well defined, medium in size, length 1.4 x width, without robust setae; propodus very broad, slightly curved, length 1.7 x width, without tooth on posterior margin, with tooth on posterodistal corner; dactylus, length 0.74 x propodus.

Peraeopod 3: coxa not fused to peraeonite 3 in male or female, length 3.3 x depth, without anteroventral lobe; basis length 1.8 x breadth, without inflated anterodorsal corner, with plumose setal group, without denticles along anterior margin; ischium length 1 x breadth; merus without ridges; carpus with 1 plumose seta along distal half of anterior margin, with 3 plumose setae along distal half of posterior margin; propodus with 3 plumose setae along posterior margin. Peraeopod 4: coxa not fused to peraeonite 4 in male or female, length 1.9 x depth, without anteroventral lobe; basis length 1.7 x breadth, without setal group along anterior margin; ischium short, length 0.9 x breadth; carpus with 1 plumose setae along distal half of anterior margin, with 2 plumose setae along distal half of posterior margin; propodus with 3 plumose setae along posterior margin. Peraeopod 5: coxa, length 1.7 x depth, without patches of small setae; anterior lobe of merus not extending beyond anterior margin of carpus, posterior lobe with 3 plumose setae; propodus with 1 seta along posterior margin, dactylus short, uncinate with two accessory spines. Peraeopod 6: coxa without patch of small setae; basis with short, sparse setae anteriorly, without small denticles along posterodistal margin; merus, length 1.6 x breadth, without small anterodistal lobe; carpus without anterodistal lobe, with posterodistal lobe, posterodistal corner bearing small setal bunch; propodus, anterodistal corner bearing large setal bunch; dactylus short, uncinate with two accessory spines. Peraeopod 7: coxa tapering and truncated posteriorly, without patch of small setae; basis without denticles along anteroproximal margin, without small denticles along posterodistal margin; merus, length 1.7 x breadth, without small anterodistal lobe, posterodistal corner bearing small setal bunch; carpus without anterodistal lobe, with well-developed posterodistal lobe, anterodistal corner bearing small setal bunch; propodus, posterodistal corner without setal bunch, anterodistal corner bearing large setal bunch; dactylus short, uncinate with two accessory spines.

Oostegites: from gnathopod 2 to peraeopod 5. Gills: from peraeopod 3 to peraeopod 6.

Pleopods 1 to 3: decreasing in size. Pleopod 1: peduncle without patch of small setae, with 2 small distomedial hooks; rami subequal in length; inner ramus withotlt patch of small setae, 6-articulate;. outer ramus, article 1 with straight medial margin, 7-articulate. Pleopod 2: peduncle without patch of small setae, with 1 small distomedial hook; biramous, ramus without patch of small setae, inner ramus reduced, I-articulate, length 0.5 x outer ramus; outer ramus broad, 3­ articulate, without patch of small setae. Pleopod 3: peduncle without patch of small setae, with 1 small distomedial hook; inner ramus absent. Uropod 1: biramous, peduncle with distoventral corona of cuticular teeth, length 1 x outer ramus, without distoventral spine; outer ramus with lateral row of denticles, with 4 lateral setae, with large apical robust seta; inner ramus length 0.8 x outer ramus, without setae, with apical robust seta. Uropod 2: uniramous, peduncle length 2.6 x breadth, 1.7 x ramus; ramus small, with denticles and 1 apical robust seta. Uropod 3: uniramous, peduncle length 1.5 x breadth; ramus with 2 curved spines. Telson: length 0.7 x breadth, cleft 0.74 x length, each lobe with 14 to 11 anteriorly directed spines in two rows.

Tube. Composed of annulated fine detrital grains with large grains of sand or shell grit at one end.

Etymology. The name africana refers to the distribution of the species.

Remarks. Notopoma africana shows similarities to N. fallohidea in the long slender antenna and deeply cleft telson, but in N. africana the mandibular palp is more slender, the outer plate of maxilla 1 has 10 setal-teeth, article 2 of the maxillipedal palp is longer and pleopod 3 is uniramous.

Notopoma sismithi also has a long slender first antenna and the maxillipedal palp article 2 is long and slender as in N. africana . But N. sismithi has a shorter, broader mandibular palp and the shape of the palm in the male second gnathopod is convex.

Distribution. South-east of St Lucia, South Africa, Indian Ocean in 680 m depth.

Figures

Fig. 9. Notopoma africana n.sp., lateral view, urosome, telson, male holotype, 2.48 mm, SAM A15547; dorsal view, male paratype, SAM A41201; lateral view, female paratype, SAM A41201, off St. Lucia, South Africa. Scales for urosome and telson represent 0.05 mm.

Fig. 10. Notopoma africana n.sp., male holotype, 2.48 mm, SAM A15547; off St. Lucia, South Africa. Scales. represent 0.1 mm.

Fig. 11. Notopoma africand n.sp., male holotype, 2.48 mm, SAM A15547; female paratype, SAM A41200; off St. Lucia, South Africa. Scales represent 0.1 mm.

Fig. 12. Notopoma africana n.sp., tube; off St. Lucia, South Africa.