Byblisoides richardi, Peart, 2018

Peart, Rachael A., 2018, Antarctic and New Zealand Byblisoides (Amphipoda: Ampeliscidae) with a key to the world species, Zootaxa 4441 (2), pp. 347-365 : 355-362

Byblisoides richardi n. sp.

( Figs. 6–10 )

Type material. Holotype: NIWA 6948, ovigerous female, 14 mm (no eggs), Chatham Rise, 43.0017°S 179.002°W, 546 m, 12/09/1989, V371.

Paratype: NIWA 6939, 1 specimen, Chatham Rise, 44.0875°S 177.0008°E, 1086 m, 16/09/1989, V386; NIWA 126935, 1 specimen, Chatham Rise, 43.5874°S 179.3779°E, 520–529 m, 09/04/2007, TAN0705/83.

Other material examined. NIWA 31838, 1 specimen, female, Kaikoura Canyon, 42.9468°S 174.4762°E, 950–971 m, 28/04/2007, TAN0705/291, coarse sediment; NIWA 31813, 1 specimen, Chatham Rise, 42.7872°S 176.4266°E, 996–1009 m, 16/04/2007, TAN0705/163; NIWA 31783, 1 specimen, Chatham Rise (south), 44.4815°S 177.1448°E, 1238–1241 m, TAN0705/46; NIWA 31781, 1 specimen, Chatham Rise (south), 44.48133°S 177.1430°E, 1230–1235 m, TAN0705/43; NIWA 126933, 3 specimens, Chatham Rise, 43.0390°S 174.5595°E, 933–940 m, 13/04/07, TAN0705/127; NIWA 126948, 5 specimens, Chatham Rise, 42.4692 °S 176.4291°E, 1023–1026 m, 16/04/2007, TAN0705/160; NIWA 126952, 1 specimen, Chatham Rise, 43.5874°S 179.3779°E, 520–529 m, 09/04/07, TAN0705/83; NIWA 126937, 2 specimens, Chatham Rise, 43.1742°S 175.3313°E, 638–644 m, 14/04/2007, TAN0705/136; NIWA 126938, 1 specimen, Chatham Rise, 43.1742°S 175.3313°E, 638–644 m, 14/04/2007, TAN0705/136; NIWA 126940, 6 specimens, Chatham Rise, 43.1742°S 175.3313°E, 638–644 m, 14/04/2007, TAN0705/136; NIWA 126942, 1 specimen, Chatham Rise, 42.4692°S 176.4291°E, 1023–1026 m, 16/04/2007, TAN0705/160; NIWA 126950, 2 specimens, Chatham Rise, 42.7872°S 176.4266°E, 996–1009 m, 16/04/2007, TAN0705/136; NIWA 126949, 2 specimens, Chatham Rise (south), 44.2917°S 177.0848°E, 1235–1239 m, TAN0705/49; NIWA 126954, 1 specimen, Chatham Rise, 42.4692°S 176.4291°E, 1023–1026 m, 16/04/2007, TAN0705/160; NIWA 126939, 1 specimen, Chatham Rise, 42.4692 °S 176.4291°E, 1023–1026 m, 16/04/2007, TAN0705/160; NIWA 126951, 1 specimen, Chatham Rise (south), 44.2917°S 177.0848°E, 1235–1239 m, TAN0705/49; NIWA 126945, 1 specimen, Chatham Rise, 42.4692 °S 176.4291°E, 1023–1026 m, 16/04/2007, TAN0705/160; NIWA 126955, 1 specimen, Chatham Rise, 43.1742°S 175.3313°E, 638–644 m, 14/04/2007, TAN0705/136; NIWA 31806, 2 specimens, Chatham Rise, 43.2908°S 184.4377°E, 638–644 m, 14/04/2007, TAN0705/138; NIWA 31819, 1 specimen, Chatham Rise, 42.5390°S 178.33817°E, 1404–1414 m, 20/04/2007, TAN0705/203; NIWA 31762, 1 specimen, Chatham Rise, 45.0583°S 175.4743°E, 1238–1258 m, 03/04/2007, TAN0705/15; NIWA 126936, 1 specimen, Chatham Rise (south), 44.2917°S 177.0848°E, 1235–1239 m, TAN0705/49; NIWA 126947, 1 specimen, Chatham Rise, 43.5874°S 179.3779°E, 520–529 m, 09/04/07, TAN0705/83; NIWA 6936, 1 specimen, Chatham Rise, 42.8308°S 178.9925°E, 1048 m, 11/09/1989, V369; NIWA 6942, 2 specimens, Chatham Rise, 42.5720°S 176.995°E, 1390 m, 17/09/1989, V392; NIWA 6950, 1 specimen, Chatham Rise, 43.8245°S 176.9818°E, 495 m, 14/09/1989, V379; NIWA 6951, 1 specimen, Chatham Rise, 43.0017°S 179.0002°E, 546 m, 12/09/1989, V371; NIWA 31770, 1 specimen, Chatham Rise, 44.1313°S 174.8445°E, 516–518 m, 04/04/07, TAN0705/25; NIWA 63941, 1 specimen, Chatham Rise, 42.1250°S 174.5395°E, 1190 m, 25/04/2010, TAN1004/104; NIWA 42878, 2 specimens, Chatham Rise, 43.1712°S 174.4671°E, 555–558 m, 28/04/07, TAN0705/289; NIWA 126941, 3 specimens, Challenger Plateau, 40.1277°S 170.2115°E, 803–805 m, 05/06/2007, TAN0707/105; NIWA 126943, 3 specimens, Challenger Plateau, 40.8883°S 170.855°E, 529–534 m, 06/06/2007, TAN0707/119; NIWA 126946, 1 specimen, Challenger Plateau, 40.8883°S 170.855°E, 529–534 m, 06/06/2007, TAN0707/119; NIWA 126944, 1 specimen, Challenger Plateau, 38.6177°S 168.9428°E, 480–482 m, 29/05/07, TAN0707/29; NIWA 126956, 1 specimen, Challenger Plateau, 38.6223°S 168.9453°E, 478 m, 29/05/07, TAN0707/26; NIWA 126953, 1 specimen, Chatham Rise, 43.8363°S 176.7092°E, 478–479 m, 05/04/2007, TAN0705/41.

Diagnosis. Anteroventral corner of head acute, produced to length of anterior margin of head. Antenna 1 short, reaching to three-fourths of antenna 2 peduncle article 4, flagellum with one (male) or two (female) articles. Coxa 1 ventral margin not strongly angled anteriorly, broadly rounded. Pereopod 5 basis posterior margin weakly uneven, slightly sinuous. Pereopod 7 carpus anterior margin without plumose setae. Pereopod 7 basis posteroventral corner rounded. Uropod 2 inner ramus bearing marginal robust setae.

Description. Based on holotype female, 14 mm length (ovigerous). Head anteroventral corner produced forward, reaching just past the anterodorsal corner of the head, anterior margin, excavate at antenna 2 insertion, antennal lobe straight, rostrum absent, head longer than deep, ventral margin straight. Antenna 1 short, reaching to three-fourths length of antenna 2 peduncle article 4; peduncle article 1 longer than article 2 (1.3 ×), article 2 longer than article 3 (4 ×), article 3 shorter than article 1 (0.2 ×); flagellum shorter than peduncle, comprising of two articles (article 1 longest, but appears fused with article 2), ventral margin of peduncle article 1 with long plumose, slender setae, flagellum margins lined with short slender setae. Antenna 2 comparatively stout, reaching to just under half body length; 2.3 × length of head; peduncular article 4 slightly longer than article 5 (1.2 ×), article 5 ventral and dorsal margin smooth, with long, slender, strong setae; flagellum shorter than peduncle, with 4 articles.

Mandible molar well-developed, triturating, 7 plumose robust setae in accessory setal row; incisor toothed; lacinia mobilis with many teeth of different sizes; palp long, article 1 very short, article 2 longer than article 3 (2.0 ×) and slightly curved with sparse setae on inner margin, article 3 longer than article 1 (2.5 ×), inner margin smooth and weakly setose. Lower lip bilobed, inner plate half height of outer. Maxilla 1 inner plate rounded and medium sized, with long slender plumose seta; outer plate topped with toothed robust setae; palp with 2 articles, article 2 not reaching length of toothed robust setae on outer plate, tipped with 3 long plumose setae and no facial slender setae. Maxilla 2 inner plate similar length to outer plate, both tipped with long plumose setae. Maxilliped inner plate very short, rounded, tipped with 2 short robust setae and 2 slender setae; outer plate not twisted around palp, inner lateral margin lined with smooth robust setae becoming slender plumose setae distally. Maxilliped palp broad, simple; article 2 broad, bearing many strong, slender plumose setae and 4 robust setae; article 3 ovoid (narrow proximally), not folded over article 2, reaching only one-third length, strongly setose; article 4 straight, acutely tipped, reaching two-thirds length of article 3.

Gnathopod 1 coxa reaching just past head anterior margin, coxa slightly expanded distally, ventral margin broadly rounded, lined with long plumose slender setae, and few medial plumose setae, posteroventral corner with small tooth; basis narrow, lateral margins lined with long plumose, slender setae, medial setae long and plumose; merus lobate and strongly setose particularly medially and posteriorly; carpus longer than merus and longer than propodus, strongly setose, particularly medially and posteriorly with long plumose setae, slightly lobate; propodus ovoid, weakly subchelate, palm not well defined, anterior and posterior margins and medially lined with long plumose slender setae, slight anterodistal lobe, posterior margin slightly serrate; dactylus short and curved, onethird length of propodus, inner margin proximally with several teeth, distally with small setae. Gnathopod 2 coxa similar length and shape to coxa 1, fringed with many medial and marginal long plumose setae; basis long and narrow, posterior and anterior margins with fringe of long slender plumose setae, merus with rounded posterior lobe, long plumose setae on both anterior and posterior margins and medially; carpus considerably longer than merus (2.6 ×) and longer than propodus (1.8 ×), narrow and not lobate, covered in long, plumose setae (mainly on posterior margin); propodus narrow, ovoid, covered in long plumose setae (mainly on posterior margin and medially); dactylus short, about one-third length of propodus and slightly curved, inner margin serrate and setose.

Pereopod 3 coxa resembling coxa 2, without posteroventral tooth; basis long and narrow, anterior and posterior margins with short setal fringe; merus narrow, shorter than basis, subequal to carpus and propodus together, both margins with sparse long plumose setae; carpus with long plumose setae on posterior margin; propodus longer than

carpus, without setae on margins, posterior margin slightly concave; dactylus long and narrow, slightly curved, shorter than propodus.

Pereopod 4 coxa trapezoid, posterior margin with extended truncated lobe, posterior margin below lobe concave, ventral margin straight and strongly setose, anteroventral corner subacute; basis shorter than coxa, posterior margin smooth with fringe of long plumose setae along the whole length, anterior margin with short slender setae along length; ischium setose along posterior margin; merus long and narrow, shorter than basis, longer than carpus and propodus together, setose with plumose setae along complete length of posterior margin and distal half of anterior margin; carpus shorter than propodus, setose along posterior margin; propodus long and narrow, setose on proximal anterior margin; dactylus long, narrow and straight, shorter than propodus.

Pereopod 5 basis skewed ovoid, narrow distally, anterior margin broadly rounded evenly, lined with long plumose setae, anterior margin uneven, bisinusoidal, bilobate with medium proximal distal lobe; ischium with acute posterior lobe; merus longer than ischium, with one long plumose seta on anterior margin, no setae on posterior margin; carpus longer than merus, longer than propodus, weakly setose along anterior margin (all plumose), slight posterodistal lobe, bearing two long strong, slender setae; propodus narrow, plumose setose along distal half of anterior margin, posterior margin with row of setules, anterodistal lobe present and tipped with 2 very long, strong, slender setae; dactylus short, weakly curved and smooth.

Pereopod 6 basis nearly rounded, anterior margin evenly rounded, lined with short slender setae proximally and many long plumose setae distally, posterior margin rounded proximally and narrow distally, with only distal setae, basis with small anterodistal lobe; ischium with acute posterior lobe; merus longer than ischium, not lobate, anterior margin with three slender setae but no robust setae, posterior margin without setae; carpus longer than merus and longer than propodus, anterior margin lined with 3 long robust setae, anterior margin no setae, distal corner produced distally with 2 long robust setae; propodus and dactylus damaged and broken in holotype, but similar to pereopod 5 distal articles in intact specimens. Pereopod 7 basis widest distally, posteroventral margin broadly rounded, lobe reaching just past merus, medial surface partially setose, anterior margin not setose, ventral and partly posterior margin lined with long plumose setae extending to junction with ischium, posterior corner smooth; ischium short and not setose, except for anterodistal corner; merus as long as ischium, not lobate, anterior margin without robust setae, posterior with 3 long plumose setae and distally with robust seta; carpus narrow, longer than merus, subequal to propodus, anterior margin without robust setae and 2 distal slender setae, posterior margin with long plumose slender seta, with 2 short distal robust setae; propodus long and narrow, anterior margin without setae, posterior margin with 2 robust setae; dactylus long, straight, narrow, as long as propodus.

Pleon. Epimeron 1 posteroventrally broadly rounded, ventral margin with small proximal robust setae. Epimeron 2 posteroventrally broadly rounded, ventral margin with small proximal robust setae. Epimeron 3 posteroventrally produced to form strong rounded tooth, posterior margin convex, ventral margin with 4 small proximal robust setae. Urosomite 1 produced weakly to form small, rounded–subacute, unilobed carina. Uropod 1, in situ, reaching to tip of uropod 2 rami; peduncle longer than rami, outer margin lined with 2 short robust setae, inner margin without robust setae, but with 2 slender setae, medial with 3 robust setae; rami subequal in length, outer ramus lined with 4 robust setae; inner ramus with 4 robust marginal setae. Uropod 2 peduncle longer than rami, outer margin with 6 robust lateral setae and 1 medial robust setae; without medial fringe of long, plumose, slender setae; inner ramus equal in length to outer ramus; outer ramus with 4 short marginal robust setae, and long subterminal robust seta; inner ramus 3 short marginal robust setae. Uropod 3 peduncle shorter than rami, with 3 distal short robust setae; inner ramus shorter than outer ramus, both rami narrow; inner ramus lined with long robust setae laterally (both margins); outer ramus with 4 short robust setae laterally. Telson longer than wide (1.4 ×), 67 % cleft; each lobe rounded truncated distally, each lobe with 2 dorsal robust setae, 1 robust apical and 1 slender apical seta.

Male variations. Based on paratype, male, 15 mm. Antenna 1 flagellum with 1 long article, lined with long slender setae. Antenna 2 article 4 subequal to article 5. Epimeron 3 posteroventral corner tooth more acute. Urosomite 1 carination more defined laterally. Uropod 3 inner ramus shorter than outer ramus; both rami with slender plumose setae on margins. Telson with 1 dorsal robust seta per lobe, 1 robust seta and 1 slender plumose seta apically per lobe.

Other variations. Most variation is size related including the setation on the antennae (increasing with size), the extent of the carination on urosomite 1 (the height with respect to the rest of the urosome, and the extent of production of the posterior corner, depending on moult stage and age—more sharply defined immediately after a moult). There are also slight variations in proportions and setation of the pereopod 3 and 4 distal articles including length of the dactylus to the propodus and increased setation with size.

Etymology. This species is named for Dr Richard Wysoczanski, whose project, along with Dr Monica Handler brought about the discovery of this species. Used as a noun in the genitive.

Remarks. Byblisoides richardi n. sp. is closest morphologically to B. esferis and B. monicae n. sp. The differences and similarities with B. richardi and of B. monicae are discussed in the Remarks of the latter. Again, although slight, the differences between B. richardi and B. esferis are significant at specific level, including antenna 2 length 2.3 × head length (versus 1.5 × in B. esferis ), the coxa 1 ventral margin being evenly rounded (versus slightly projected forward), the coxa 4 posterior margin below lobe being concave (versus straight), the pereopod 5 carpus being longer than the merus (versus subequal to merus), the pereopod 7 merus being subequal to the ischium (versus longer than ischium), and urosomite 1 with an acute projection in lateral view (versus carination not discernible).

Distribution. Chatham Rise and Challenger Plateau, New Zealand; 475–1414 m depth.

Figures

FIGURE 6. Byblisoides richardi n. sp. Holotype, NIWA 6948, female, length 14 mm, Chatham Rise, Pacific Ocean, 546 m, habitus, head and epimeron. Paratype, NIWA 6939, male, length 15 mm, Chatham Rise, Pacific Ocean, 1086 m. Habitus. Scale represents 0.5 mm.

FIGURE 7. Byblisoides richardi n. sp. Holotype, NIWA 6948, female, length 14 mm, Chatham Rise, Pacific Ocean, 546 m. Paratype, NIWA 6939, male, length 15 mm, Chatham Rise, Pacific Ocean, 1086 m, antenna 1. Scales represent 0.5 mm.

FIGURE 8. Byblisoides richardi n. sp. Holotype, NIWA 6948, female, length 14 mm, Chatham Rise, Pacific Ocean, 546 m. Scales represent 0.5 mm.

FIGURE 9. Byblisoides richardi n. sp. Holotype, NIWA 6948, female, length 14 mm, Chatham Rise, Pacific Ocean, 546 m. Paratype, NIWA 6939, male, length 15 mm, Chatham Rise, Pacific Ocean, 1086 m, telson and uropod 3. Scales represent 0.5 mm.

FIGURE 10. Byblisoides richardi n. sp., distribution, New Zealand.