Neobirsteiniamysis inermis ( Willemoes-Suhm, 1874 )

Daneliya, Mikhail E., 2023, Mysid Subfamily Boreomysinae (Crustacea: Mysida: Mysidae) in the Southeast Australian Deep-sea, Records of the Australian Museum (Rec. Aust. Mus.) 75 (2), pp. 87-124 : 110-120

Neobirsteiniamysis inermis ( Willemoes-Suhm, 1874)

Figs 11–15

Petalophthalmus inermis Willemoes-Suhm, 1874 : xv, xix; 1876a: 575; 1876b: 588, 592. G. O. Sars, 1885a: 178, 179.

Petalophthalmus armiger Willemoes-Suhm, 1874 : xiv (partim, female only); 1875: 41, 44, pl. 7, figs 1, 3–14 (partim, female only); 1876b: 588 (partim, female only).— Perrier, 1893: 1026 (partim, female only).

Boreomysis scyphops G. O. Sars, 1879b: 429–430 ; 1883: 34; 1885a: 12, 35, 172, 174, 178, 179, 184, plate

32, figs 10–20; 1885b: 56, plate 6, figs 1, 2; 1886: 14.—Filhol, 1885: 145.— Norman, 1886: 9; 1905: 10.—Hansen, 1887: 212; 1908: 99–100, fig. 1; 1910:

5, 25; 1921: 71; 1927: 22.— Stebbing, 1893: 268, 269.— Ortmann, 1894: 106.— Ohlin, 1901: 71, 73, 90.—Calman, 1901: 23; 1909: 173, 180.—Gerstaecker & Ortmann, 1901: 621, 654, 671, 672, 675, 677, 678, 681, 683.— Zimmer, 1904: 429, 433, 473, 480, 483, 484, 486, 488, figs 43–46; 1905: 149; 1909: 52, 57, figs 87–90.—Holt & W. M. Tattersall, 1906: 22.— Linko, 1908: 39, 41, 42.— Stephensen, 1918: 65.— Illig, 1930: 559.— Nouvel, 1943: 6, 46, 103; 1950: 4.— Zenkewitch, 1954: 82.—Elofsson & Hallberg, 1977: 169, 170, 174, 176, figs. 1A, 3A, 4–7.—Staff of the Zoological Society of London, 1985: 399.— Kathman et al., 1986: 108.— Brattegard & Meland, 1997: 70, 78, 79.

Boreomysis suhmi Faxon, 1893: 218 .

Boreomysis distinguenda Hansen, 1908: 100 , fig. 2a–b; 1910: 5, 25; 1927: 22.—W. M. Tattersall, 1913: 866, 869.— Zimmer, 1927: 623.— Illig, 1930: 559.

Boreomysis inermis .—W. M. Tattersall, 1951: 8, 46–47.—O. S. Tattersall, 1955: 6, 19, 20, 22, 25, 67, 75.—Gordan, 1957: 342.—Holmquist, 1957: 9.—Birstein & Tchindonova, 1958: 279, 282–284, 335, 348–349, 350, fig. 9.—Birstein & Tchindonova, 1962: 62.— Ii, 1964:

8, 9, 13, 18–22, 32, 33.— Mauchline & Murano, 1977: 49.— Mauchline, 1980: 227, 235.—Băcescu, 1981:

36, figs A–Д.— Kathman et al., 1986: 25, 29, 108, figs a–e.— Laubitz, 1986: 15.— Lancraft et al., 1989: 227.— Ledoyer, 1989: 67; 1990: 37, 40, 44; 1995: 602, 603.— Müller, 1993: 25.—Hargreaves, 1997: 54, 56, 59, 61,

63, 64.—Brandt et al., 1998: 5, 6, 8.—De Jong-Moreau, Casanova & Casanova, 2001: 235, 236, 237, 238–240, figs 1A, B, E, 3A.— Meland & Willassen, 2007: 1086, 1091, 1100.—Castellani et al., 2017: 479, figs. O–R.

Not Boreomysis inermis Hansen, 1910: 11 , 24, 26, 27,

pl. II, fig. 4a–c.— Illig, 1930: 560.— Nouvel, 1943: 51.—Holmquist, 1956: 427–428, 442–443 ( Boreomysis hanseni Holmquist, 1956 ).

Birsteiniamysis inermis .— Tchindonova, 1979: 102;

1981: 28–29; 1993: 153–155.—Staff of the Zoological Society of London, 1985: 398, 399.—Petryashev, 1989: 378, 382, 384, plate 15–1d; 1993a: 79, 93, 94, 102,

104, fig. 3–3; 1993b: 71, 75, figs 1, 2, 3; 2004a: 126,

140, 141, 142, fig. 1; 2004b: 132; 2005a: 10; 2005b: 963–964, 968, 970, figs 4 (6–11); 2009a: 98; 2009b:

125, fig. 2–1, 3–7, 8; 2014a: 184, 187; 2014b: 150, 151.— Sirenko et al. 1996: 349, 351.— Fukuoka, 2009: 418.— Wittmann et al., 2014: 201, 217, 238, 241, 347,

figs 54.5B, 54.14A, 54.24C, 54.25L.— Wittmann, 2020: 6.— Kou et al. 2020: 3, fig. 9.

Birsteiniamysis inermis ochotsckii Tchindonova, 1981:

29, nomen nudum.—Staff of the Zoological Society of London, 1985: 398 (first mention as an undescribed subspecies).

Birsteiniamysis scyphops .— Tchindonova, 1981: 28–29 (removed there from synonymy).—Staff of the

Zoological Society of London, 1985: 399.

Boreomysis inermis peruana Băcescu, 1981: 36 , figs A–D, nomen nudum.

Boreomysis scyphos .— Ledoyer, 1989: 67; 1995: 603

(lapsus calami).

Neobirsteiniamysis inermis .—Hendrickx et al., 2020: 21.—Hendrickx & Tchindonova, 2020: 2.—Hernández-Payán & Hendrickx, 2020: 2, 3, 11, 14, figs 1–10.

Type specimens. Probably lost.

Type locality. Southern Indian Ocean near Crozet Islands .

Material. Female , 49 mm, Southern Ocean, Great Australian Bight, 34°32'55"S to 34°34'27"S 129°36'07"E to 129°34'18"E, 3389–3540 m, 21 Apr 2017, coll. RV Investigator, BPT, A. Murray, F. Criscione, IN2017 _ C01_198, beam trawl ( AM P.102493); subadult female, 38 mm, 2 juveniles, Bass Strait , 39°27'43"S to 39°27'54"S 149°16'37"E to 149°14'46"E, 2774– 2695 m, 22 May 2017, coll. RV Investigator, BPT, L. E. Hughes, F. Köhler, E. K. Kupriyanova, IN2017 _ V03 _023, BES ( AM P.106627).

Diagnosis. Telson ( Fig. 13B,E ) 2.3–3.8 times as long as wide anteriorly, its lateral margins nearly straight or slightly convex, with 35–59 spiniform setae, longer alternated by one to three shorter; cleft 0.16–0.25 of telson length, with convex margins, bearing 58–60 spinules. Eyes ( Figs 11 , 12A , 13A ) reaching distal margin of antennular peduncle segment 1 or half of segment 2, laterally flattened, cup-shaped, with lateral hollow. Antennular peduncle ( Figs 11 ; 12A,B,D ; 13A ) not reaching half of antennal scale; segment 3 is 1.5–3.0 times as long as segment 2. Antennal scale ( Fig. 12A,G ) 4.5–7.0 times as long as wide, apically truncated, with obtuse-angular distomedial corner.Antennal peduncle stretching beyond half of antennal scale. Uropods with exopod ( Fig. 13B,F ) rather wide, 4.3–5.3 times as long as wide; outer margin with one to three spiniform setae at 0.22–0.29 of ramus length. Uropodal endopod ( Fig. 13F ) with one to five spiniform setae.

Comparison. Neobirsteiniamysis inermis differs from N. caeca by the less transparent cuticle (rather thin and transparent in N. caeca ); the less protruding eyes (reaching antennular peduncle segment 3 in N. caeca ); the presence of the concavity on the eye lateral side (distally in N. caeca ); the antennal scale being five to seven times as long as wide (four times as long as wide in N. caeca ), with distomedial corner obtuse-angular (acute-angular in N. caeca ); the antennular peduncle stretching beyond the half of the antennal scale (not reaching the half of the scale in N. caeca ); the uropods slightly wider, with exopod 4.3–5.3 times as long as wide (5.6 times as long as wide in N. caeca ), bearing spiniform setae at 0.22–0.29 of the ramus length (at 0.16 of the ramus length in N. caeca ); the telson with nearly straight lateral margins (convex, almost rounded in N. caeca ); the cleft 0.16–0.25 of the telson length, with convex margins (0.14, with straight margins in N. caeca ).

Description of Australian specimens (females). Anterior margin of carapace angular apically rounded, not reaching antennular peduncle, subapically slightly concave, dorsolaterally convex; laterally without minute concavity; anteroventral lobes large, triangular, apically rounded. Posterior margin of last abdominal segment, lateral lobes (scutella paracaudalia) triangular, apically pointed; ventrolateral lobes apically rounded; ventral lobes concave with blunt inner process. Telson 1.2–1.4 times as long as last abdominal segment, 2.3–2.9 times as long as maximum width, and 0.42–0.56 times as wide posteriorly as its largest width; lateral margins nearly straight, bearing about 45–57 spiniform setae, with longer alternated by groups of one to three shorter; longest terminal spiniform seta 0.07–0.08 of telson length; cleft 0.18–0.24 of telson length, with convex margins, bearing about 58–60 spinules.

Eyes large, laterally flattened, cup-shaped, with lateral hollow, almost square in lateral view, reaching half of antennular peduncle segment 2, 0.61 times as long as head width. Medially with concavity, flanked by keel, and dorsal papilla.

Antennula. Peduncle not reaching half of antennal scale, rather slender. Segment 1 slightly longer than segment 3; proximally with a group of about eight short lateral setae; distally with long setae: single lateral and three bunches, distolateral, distomedial and anterior. Segment 2 with lateral bunch of short setae, long medial seta and two long anterolateral setae. Segment 3 is 2.4 times as long as segment 2; distally with one long medial seta, anterior tubercle with short apical seta and a group of eight short posteromedial setae. Outer flagellum rather thick basally, with numerous long smooth ventral setae, arranged in pattern of double waving line.

Antenna. Sympod with lateral acute process; antennal cone small, spindleform. Peduncle segment 2 is 1.5 times as long as segment 3, each with groups of medial long setae. Antennal scale about 5 times as long as wide, apically truncated, with obtuse-angular distomedial corner and distolateral spine projecting beyond distal margin.

Labrum, proximal articulated lobes with numerous spinules. Mandible: left corpus, processus incisivus and lacinia mobilis both 5-cuspate, rather similar, pars centralis with nine serrated setae, pars praemolaris with fine setules, pars molaris rather broad, with apical spinules; right corpus, precessus incisivus and lacinia mobilis smaller than on left corpus, pars centralis with rather short, spine-like setae, pars praemolaris with fine setules, pars molaris rather narrow, with apical spinules. Mandibular palp segment 2 with rather long setae set apart, medial setae smooth, other setae with setules; segment 3 is 0.74 times as long as segment 2; with five lateral, one anterior distomedial and more than 50 long, densely set, medial setae; its margins nearly parallel. Maxilla 1. Outer ramus with ten posterior serrated setae, three of them grouped medially and three shifted to medial margin, apical spiniform setae smooth. Inner ramus with four lateral, ten medial and six apical long setae, four apical setae distally serrated, similar to those of maxilla 2 and maxilliped 1 endites. Maxilla 2. Exopod oval, 2.2 times as long as wide, about as long as endopod, with plumose setae. Endopod segment 1 with eleven anteromedial and four posteromedial setae, segment 2 is 2.2 times as long as wide, with lateral plumose setae and apical serrated setae; coxal endite notably prolonged; basal endites with strong serrated setae, similar to those of maxilliped 1 endites.

Maxilliped 1. Coxa with one short, plumose medial seta. Basis endite rather long, reaching proximal part of carpus, with long setae of two types: thinner, longer and flexible, with setules, and thicker, shorter and stout, distally with rough serrations and spear-like apex. Preischium endite short, but well-established, compared to rather reduced ischium endite; both with long plumose setae. Merus the longest segment, 2.6 times as long as wide, with long, plumose medial setae. Ischium and merus with a few weakly setulose lateral setae. Carpopropodus 0.7 times as long as merus, distally with long, plumose setae on medial and lateral margins. Dactylus 0.56 of carpopropodus, proximally with numerous long, weakly setulose setae; its distomedial margin with about 12 serrated setae; distolateral strong, serrated seta near dactylary unguis. Unguis strong, serrated, 0.68 of dactylus length.

Maxilliped 2. Exopod basis with acute distolateral angle; flagellum, three proximal segments differentiated, two large and one small between them. Endopod with rather thin, prolonged segments, bearing numerous long medial setae. Preischium with seven setae. Ischium with small distomedial lobe. Carpopropodus 0.9 of merus length, with distomedial concavity, marked in its proximal part with five strong spine-like, apically thin setae; numerous setae around distal third. Dactylus with numerous setae around; its medial setae serrated, differentiated into thin long and short claw-like setae. Unguis smooth.

Pereopods. Oostegite of pereopod 3 reaching mid of merus. Exopod basis with smoothly rounded distolateral angle. Preischium with five or six long setae. Ischium and merus with numerous long medial, anteromedial and posterolateral plumose setae. Merus also with numerous long plumose lateral and anterolateral setae; its anteromedial setae distally converge to anterolateral angle. Carpus with nine anteromedial groups of long plumose setae and four or five single shorter lateral setae; anteromedial groups made of anterior row of curved setae, one or two medial rather long setae and single straight thinner seta. Propodus with smooth medial and long plumose lateral setae; four medial paradactylary setae long and finely serrated. Dactylus with one lateral seta, one anterodistal seta and a bunch of thin medial paraungual setae. Unguis rather strong. Length ratio between ischium, merus, carpus, propodus and dactylus (including unguis), respectively: 2.6–2.9 / 4.9–5.6 / 2.5–2.6 / 1.2–1.4 / 1.

Pleopods uniramous, increasing in length posteriorly. Uropodal exopod 1.6 times as long as last abdominal segment, 1.3 times as long as telson, 5.3 times as long as wide and 1.2–1.3 times as long as endopod. Uropodal exopod with one or two lateral spiniform setae at 0.22–0.25 distance from ramus base (ratio between segment 1 and 2 length 0.31–0.32). Endopod with one or two medial spiniform setae set apart.

Body length of female 49 mm (40–85 mm in other parts of the range). The largest species in the order ( Mauchline & Murano, 1977).

Coloration uniformly red, crimson ( Fig. 11 ) (previously also Elofsson & Hallberg, 1977).

Variation. In additional to variation of the diagnostic characters, mentioned above, the carapace anterior margin can be apically from rounded to acute with straight to concave lateral sides. Eyes from rather oblong and flattened dorsoventrally to relatively shortened and wide from lateral view. Băcescu (1981) reported the white colour of the lateral hollow of the eyes in the specimens from the Peru-Chile Trench (normally red), which may have taxonomic importance. The maxilliped 2 propodus can be with or without the distomedial concavity. Geographical regularity in the variation has not been confirmed.

Molecular characters. I was not able to obtain the DNA from the Australian specimens. The GenBank holds the following gene fragments of N. inermis specimens from the North Atlantic: 18S rRNA (AM422482) ( Meland & Willassen, 2007), mtDNA COI (MK803439), enolase (MK798080) and 28S rRNA (MK798060) ( Kou et al. 2020). I incorporated the COI sequence into the analysis in this study.

Distribution. Bipolar-amphitropical species. Originally described from sub-Antarctic waters of the Indian Ocean and the tropical Atlantic and Southern Ocean ( Willemoes-Suhm, 1874, 1875; Willemöes-Suhm, 1876a, 1876b; G. O. Sars, 1885a), it was later discovered in the North Atlantic (G.O. Sars, 1879b; Ohlin, 1901; Hansen, 1908; Hargreaves, 1997), Canary Basin ( Nouvel, 1943), in Weddell Sea (W. M. Tattersall, 1913; Ledoyer, 1990) and Scotia Sea of South Atlantic ( Lancraft et al., 1989), East Pacific, West Pacific in Bering Sea and Okhotsk Sea (W. M. Tattersall, 1951), extended further north from the South Atlantic to South Georgia (O. S. Tattersall, 1955; Tchindonova, 1993), Arctic Polar Basin (Birstein & Tchindonova, 1958; Lomakina, 1964; Mauchline, 1986; Petryashov, 1993a, b, 2004a, 2009a; Hargreaves & Murano, 1996), the Pacific sector of the Southern Ocean (Birstein & Tchindonova, 1962), Peru-Chile Trench (Băcescu, 1981), Southwestern Pacific near Macquarie Island and Southern Ocean near Balleny Islands ( Tchindonova, 1993), near Kerguelen Island ( Ledoyer, 1995), North-West Pacific off Japan (Fukuoka, 2009), and recently in the East Central Pacific off Mexico and in the Gulf of California (Hernández-Payán & Hendrickx, 2020). In the North Pacific, it is found along North American continental slope from the California Peninsula (17°N), further along Aleutian Ridge towards the Okhotsk Sea and Kuril-Kamchatka Trench (44°N) (Fukuoka, 2009). In the South Pacific, from the Peru-Chile Trench (8°25'S) and Sub-Antarctic Front to the Antarctic coast. In the Arctatlantic, from the Canadian Basin to the Canarian Basin (O. S. Tattersall, 1955; Tchindonova, 1981; Petryashev, 2005a, 2014b). First time reported from the Great Australian Bight and Bass Strait ( Fig. 16 ).

Habitat and feeding. Bathyal-abyssal (Birstein & Tchindonova, 1958; Petryashov, 1993b, 2004a, b) or bathyalpseudoabyssal ( Petryashov, 1989) species. Benthopelagic (Birstein & Tchindonova, 1958), bathypelagic ( Petryashov, 1989), suprabenthic-bathypelagic (Hargreaves, 1997), benthic (Brandt et al., 1998), nektobenthic (hyperbenthic) ( Petryashov, 2004a, 2014b) or pelagic (De Jong-Moreau et al., 2001) species. Depth 700–7200 m (Birstein & Tchindonova, 1958; Tchindonova, 1981; Ledoyer, 1995; Petryashov, 2005b). In Australian waters at 2696–3540 m. Stenothermal in the Arctic basin, found at temperatures of –1°C to –0.7°C ( Petryashov, 1989, 2004a), but generally eurythermal species, capable of living in the range between –1°C and 3.3°C ( Petryashov, 2004a). In the North Atlantic found at temperature of –1.3°C to –0.7°C, over soft bottom (G. O. Sars, 1879a; Brattegard & Meland, 1997). In the North Pacific, at temperature of 1.7°C to 2.6 °C, over muddy and sandy bottom, occasionally with presence of rocks, and salinity 33.69–34.54‰ ( Petryashov, 1993a). In the Arctic basin, at temperatures –0.88°C–+0.60°C and salinity 34.84– 34.99‰, over muddy bottom, occasionally with presence of sand, clay or rocks ( Petryashov, 1993b, 2004). Omnivorous species with phytophagous tendency: crustaceans and alga (De Jong-Moreau et al., 2001). Relatively unabundant, <10 individuals per 1000 m 3 (Hargreaves, 1997).

Remarks. Willemoes-Suhm (1874), in the letter to Carl von Siebold, written onboard HMS Challenger, provided rather short description of Petalophthalmus armiger Willemoes-Suhm, 1874 , collected from the tropical Atlantic in 1873, and P. inermis , collected the same year off Crozet Islands in southern Indian Ocean and in 1874 in Southern Ocean. Both species had very peculiar eyes, not found in any other mysids. Simultaneously he sent a detailed account with proper descriptions and illustrations of P. armiger to the Linnean Society of London, which was published a year later ( Willemoes-Suhm, 1875). He mentioned P. inermis again in two more reports he sent to the Director of the Civilian Scientific Staff, published posthumously ( Willemöes-Suhm, 1876a, 1876b), as he suddenly died in the course of the Expedition. The name indicated the absence of the prehensile structure of the mandibular palp, characteristic for other Petalophthalmus , as well as for the males of P. armiger .

G. O. Sars (1879b), probably unaware of what species Willemoes-Suhm dealt with, described much in detail and well illustrated Boreomysis scyphops (currently a junior synonym of N. inermis ), collected by the Norwegian North-Atlantic Expedition. He was the first to describe its uniform red body colour, the truncate antennal scale, pereopods and other features. Later, G. O. Sars (1883) received the Challenger material, as well as the notes and drawings of Willemöes-Suhm, but not the specimens of P. armiger , which, judging from Willemöes-Suhm’s descriptions, was rather related, in his opinion, to Boreomysis . He also synonymized P. inermis from Southern Indian Ocean with B. scyphops , although the former was described earlier than the latter. Finally, G. O. Sars was able to obtain the male of P. armiger and in a more detailed report of his work (G. O. Sars, 1885a) recognized it as distinctly belonging to Petalophthalmus . The female, described and illustrated by Willemoes-Suhm (1875), was lost. He also noticed a special incurvation of the maxilliped 2 propodus (“gnathopod” in Sars’ terminology), overlooked by subsequent authors. G.O. Sars was the first to study the nervous system of N. inermis , which has been described only for few mysid species.

Hansen (1887) assigned P. armiger female to B. scyphops . Faxon (1893) designated a new species for this female, Boreomysis suhmi Faxon, 1893 . Then Hansen (1908) compared material on B. scyphops from the North Atlantic and the Southern Ocean, found difference in the structure of the eyes and antennal scales and described the latter specimens as B. distinguenda Hansen, 1908 . The eyes of the Australian specimens in my disposal have rather square than oblong eyes, closer in this respect to the North Atlantic specimens, originally described as B. scyphops . By this, I do not find a support for Hansen’s distinction between the Northern and Southern Hemisphere species.

In his later work Hansen (1910) described another new species B. inermis Hansen, 1910 , from the East Indies expedition, probably not associating P. inermis with Boreomysis . He also (Hansen, 1921) described so called “dorsal organ” in B. scyphops , which differed from other species of Boreomysis . I do not include its description into the diagnosis of N. inermis , as we do know yet its structure in N. caeca . [“in front of the gastric groove a moderately large and rather shallow depression, at the middle of which is seen a somewhat low, a little oval, rounded and very distinct protuberance with one to three minute pits”, Hansen, 1921, p. 71]

W. M. Tattersall (1951) confirmed the difference between B. scyphops and B. distinguenda , and proposed to return the original name B. inermis instead of B. scyphops from sub-Antarctic waters, B. suhmi and B. distinguenda . The name B. scyphops was maintained only for the North Atlantic and Arctic populations. He also noticed that Hansen’s B. inermis turned out to be B. rostrata Illig, 1930 . This was later described by Holmquist (1956) as B. hanseni Holmquist, 1956 . O. S. Tattersall (1955) continued to treat B. scyphops and B. inermis separately, with the latter species distinguished by more quadrangular eyes with thicker marginal rim, following Hansen (1908).

Birstein & Tchindonova (1958) described B. caeca , closely related to B. inermis . This required an update of the diagnosis for B. inermis . According to them, the species differed by the structure of the cuticle, the eyes, the antennal scales and the uropods. Among other characters B. inermis had two (cf. one in B. caeca ) spiniform setae on the uropodal exopod and endopod. One of the new Australian specimens, which I examined, had the same number of uropodal spiniform setae as in B. caeca , otherwise constructed typically for B. inermis . I therefore exclude these characters from the updated diagnosis. The authors also followed G. O. Sars’ (1885a) view, considering the Southern and Northern Hemisphere populations of B. inermis conspecific.

Ii (1964) clearly separated B. inermis together with B. scyphops from other species of Boreomysis by the absence of ommatidia (considering them blind species), but he continued to distinguish the two species separately. He also considered that B. rostrata orientalis Ii, 1964 , maybe nearer to B. inermis Hansen, 1910 , than to its nominotypical subspecies (“variation” in his concept, p. 19, 23, 32, 33). The name inermis for the Hansen’s taxon must be altered in his opinion ( Ii, 1964), which was earlier done by Holmquist (1956), who described it as B. hanseni .

Elofsson & Hallberg (1977), in a specific study of the eye structure, actually found the thick pigment cell layer and large number of ommatidia behind it, as well as various optico-neural structures and muscles. The ommatidia lacked the dioptric structure. More details on the eye ultrastructure can be consulted in their paper. This work remained unnoticed, and the lack of eye pigmentation kept repeating as a character in keys and descriptions.

Tchindonova (1981) made a detailed study with the Antarctic and North Pacific material of B. inermis . She also had the South American collections at her disposal, but did not study them. Morphological differences between the populations of Northern and Southern Hemispheres in the world fauna, including the new taxa described here.

Boreomysinae Holt et Tattersall, 1905

Boreomysis G. O. Sars, 1869

Boreomysis (Boreomysis) G. O. Sars, 1869

Boreomysis (Boreomysis) acuminata O. S. Tattersall, 1955

Boreomysis (Boreomysis) arctica (Krøyer, 1861)

Boreomysis (Boreomysis) atlantica Nouvel, 1942

Boreomysis (Boreomysis) bispinosa O. S. Tattersall, 1955

Boreomysis (Boreomysis) brucei W. M. Tattersall, 1913

Boreomysis (Boreomysis) californica Ortmann, 1894

Boreomysis (Boreomysis) chelata Birstein et Tchindonova, 1958

Boreomysis (Boreomysis) curtirostris Birstein et Tchindonova, 1958

Boreomysis (Boreomysis) dubia Coifmann, 1937

Boreomysis (Boreomysis) fragilis Hansen, 1912

Boreomysis (Boreomysis) hanseni Holmquist, 1956

Boreomysis (Boreomysis) illigi O. S. Tattersall, 1955

Boreomysis (Boreomysis) incisa Nouvel, 1942

Boreomysis (Boreomysis) inopinata sp. nov.

Boreomysis (Boreomysis) intermedia Ii, 1964

Boreomysis (Boreomysis) jacobi Holmquist, 1956

Boreomysis (Boreomysis) latipes Birstein et Tchindonova, 1958

Boreomysis (Boreomysis) longispina Birstein et Tchindonova, 1958

Boreomysis (Boreomysis) macrophthalma Birstein et Tchindonova, 1958

Boreomysis (Boreomysis) microps G. O. Sars, 1883

Boreomysis (Boreomysis) nobilis G. O. Sars, 1879

Boreomysis (Boreomysis) obtusata G. O. Sars, 1883

Boreomysis (Boreomysis) oparva Saltzman et Bowman, 1993

Boreomysis (Boreomysis) pearcyi Murano et Krygier, 1985

Boreomysis (Boreomysis) plebeja Hansen, 1910

Boreomysis (Boreomysis) rostrata Illig, 1906

Boreomysis (Boreomysis) semicoeca Hansen, 1905

Boreomysis (Boreomysis) sibogae Hansen, 1910

Boreomysis (Boreomysis) sphaerops Ii, 1964

Boreomysis (Boreomysis) tanakai Ii, 1964

Boreomysis (Boreomysis) tattersalli O. S. Tattersall, 1955

Boreomysis (Boreomysis) tridens G. O. Sars, 1870

Boreomysis (Boreomysis) vanhoeffeni Zimmer, 1914

Boreomysis (Boreomysis) verrucosa W. M. Tattersall, 1939

Boreomysis (Petryashovia) subgen. nov.

Boreomysis (Petryashovia) insolita O. S. Tattersall, 1955

Boreomysis (Petryashovia) kistnae Pillai, 1973

Boreomysis (Petryashovia) megalops G. O. Sars, 1872

Boreomysis (Petryashovia) urospina sp. nov.

Neobirsteiniamysis Hendrickx et Tchindonova, 2020

Neobirsteiniamysis caeca (Birstein et Tchindonova, 1958)

Neobirsteiniamysis inermis ( Willemoes-Suhm, 1874)

were minimal ( Tchindonova, 1981), and she removed B. scyphops from the synonymy, suggesting that each bipolar species could equally be considered either a widespread variable species or a sibling species, found in different hemispheres. In the absence of additional material she was not ready to make final decision. In the same work Tchindonova (1981) also corrected her earlier (Birstein & Tchindonova, 1962) misidentification of B. scyphops as B. inermis . She also mentioned a new subspecies B. inermis ochotsckii Tchindonova, 1981 , without providing a description. This was first noted by the staff of the Zoological Society of London (1985), and the name is to be considered nomen nudum.

Băcescu (1981) suggested that B. inermis from the Peru-Chile Trench “possibly” belongs to a separate subspecies, B. inermis peruana . He provided some characters and mentioned “n. ssp.” after the subspecies name, but did not designate any type specimens (Băcescu, 1981, p. 36). According to the Code, Article 16.4.1 (ICZN, 1999), the type specimens do not have to be designated in the publication before the year 2000. However, the expression “possibly” makes his proposal conditional, i.e. with stated reservation (the Code Glossary), and, thus, unavailable, according to Article 15.1. By this, Boreomysis inermis peruana is a nomen nudum.

Ledoyer (1989, 1995) explicitly noted that the boreal form was not conspecific with B. inermis , but twice misspelt B. scyphops as B. scyphos . He was also, probably, unaware of Birsteiniamysis , designated for B. inermis by Tchindonova (1979, 1981, 1993). Designating informal groups for B. inermis , B. scyphops and B. caeca, Tchindonova (1993) also continued treating the first two as separate species. Simultaneously, Petryashov (1993a) accepted the combination with Birsteiniamysis , but considered B. scyphops synonymic with B. inermis , though without specifications. Hargreaves (1997) also treated B. inermis and B. scyphops as synonyms, but Brattegard & Meland (1997) still distinguished B. scyphops separately from B. inermis .

De Jong-Moreau et al. (2001) made a SEM study of the mandibles, labrum, and paragnaths. Particularly interesting was the finding of pores surrounding the apical part of the mandibular processus molaris.

Meland & Willassen (2007) obtained the first DNA sequence of B. inermis , which they still considered a part of Boreomysis . Since the specimen came from the North Atlantic, the authors evidently treated B. scyphops as the synonym of B. inermis , although this was not explicitly indicated. This was a fragment of the ribosomal 18S rRNA gene. Later Kou et al. (2020) sequenced the 28S rRNA, enolase and the mtDNA COI gene fragments from the same North Atlantic material. They accepted the species position within Birsteiniamysis .

Hendrickx et al. (2020) first time used the species name in combination with a newly designated Neobirsteiniamysis . Hernández-Payán & Hendrickx (2020) discovered that N. inermis possessed plumose setae in the telson cleft. This primitive character is rather important and usually characterizes a subfamily or a genus in various other mysid groups. Its finding in boreomysines is an outstanding discovery. However, none of the specimens at my disposal possessed such setae, and this character still requires verification. The authors also reported considerable variation in the shape of the carapace and eyes among the specimens from East Central Pacific.

Figures

Figure 11. Neobirsteiniamysis inermis, female, 49 mm, Great Australian Bight, AM P.102493. Scale (mm): 10.0. Photographed by K. G. Holmes, with permission.

Figure 12. Neobirsteiniamysis inermis. (A–F) female, 49 mm, Great Australian Bight, AM P.102493; (G) subadult female, Bass Strait, AM P.106627. (A) head, dorsal; (B) antennular peduncle, ventral; (C) setae pattern on outer flagellum of antennular peduncle, ventral; (D) antennular peduncle, dorsal; (E) proximal part of antenna, dorsal; (F) proximal part of antenna, ventral; (G) antennal scale. Scale (mm): A = 10.0; B, D–G = 1.0; C = 0.5.

Figure 13. Neobirsteiniamysis inermis. (A–D, F) female, 49 mm, Great Australian Bight, AM P.102493; (E) subadult female, Bass Strait, AM P.106627. (A) head, lateral; (B) posterior part of body, dorsal; (C) posterior margin of abdomen, lateral; (D) posterior margin of abdomen, ventral; (E) telson; (F) uropods, ventral. Scale (mm): 1.0.

Figure 14. Neobirsteiniamysis inermis, female, 49 mm, Great Australian Bight, AM P.102493. (A) mandibular palp, posterior; (B) left mandible, dorsal; (C) maxilla 1, posterior;(D) maxilla 2, posterior; (E) apical serrated seta of maxilla 2 endopod; (F) apical seta of maxilla 2 endite; (G) maxilliped 1, anterior; (H) long plumose seta of maxilliped 1 basal endite; (I) short serrated seta of maxilliped 1 basal endite. Scale (mm): A, B, D, G–I = 1.0; C = 0.5; E, F = 0.25.

Figure 15. Neobirsteiniamysis inermis, female, 49 mm, Great Australian Bight, AM P.102493. (A) maxilliped 2, anterior; (B) distal part of maxilliped 2 endopod (only modified setae shown), anterior; (C–E) dactylar setae of maxilliped 2; (F) robust seta of maxilliped 2 carpopropodus; (G) pereopod 3, anterior; (H) dactylus of pereopod 3, anterior; (I) medial seta of pereopod 3 merus; (J) lateral seta of pereopod 3 merus; (K) medial seta of pereopod 3 carpus. Scale (mm): A, B, G = 1.0; C, E, F, I–K = 0.5; D, H = 0.25.

Figure 16. Records ofthe species ofthe subfamily Boreomysinae inAustralia and adjacent waters(the whitesymbols indicate formerrecords).