Bairdoppilata simplex ( Brady, 1880 )

Brandão, Simone N., 2008, New species of Bairdioidea (Crustacea, Ostracoda) from the Southern Ocean and discussions on Bairdoppilata simplex (Brady, 1880),? Bairdoppilata labiata (Müller, 1908) and Bythopussella aculeata (Müller, 1908) *, Zootaxa 1866, pp. 373-452 : 379-384

Bairdoppilata simplex ( Brady, 1880)

(Figs. 3.20a, b; 4; 5 G, H; Tab. 3 )

1880 Bairdia simplex Brady : 51, Pl. 7.1a–d.

1890 non Bairdia simplex Brady : 492.

1969 in part Bairdoppilata ( Bairdoppilata ?) simplex , Maddocks: 77–78. 1976 Bairdia simplex, Puri & Hulings : 266, Pl. 3.11–13. 1989 non Bairdoppilata simplex, Hartmann : 211.

1993 non Bairdoppilata simplex, Dingle : 7–10, Figs.3.C–F, 4. 1993 non Bairdoppilata simplex, Hartmann : 230.

1995 non Bairdoppilata sp. cf. B. simplex, Whatley et al. : 21, 22, Pl.1.7–12. 1996 non Bairdoppilata sp. cf. B. simplex, Whatley et al. : 55, Pl. 1.3. 1997 non Bairdoppilata (Bairdoppilata) simplex, Hartmann : 47, Fig. 11. 1997 non Bairdoppilata sp. cf. B. simplex, Whatley et al. : 18, Pl.1.11–13. 1998 non Bairdoppilata simplex, Whatley et al. : 116, Pl. 1.15. 2000? Bairdoppilata cf. B. simplex, Dingle : 486.

Material. Lectotype: Bairdia simplex Brady, 1880 , 1 RV and 1 LV of the same specimen, contained on the Challenger slide no. 142, labelled “station no. 151, off Heard Island, depth 75fms (= 137m)”, BMNH cat. no. 81.5.13. This specimen was designated and described by Puri & Hulings (1976, p. 266, Pl. 3.11–13), also examined by Maddocks (1969, p. 77). This specimen is probably an adult since the calcified inner lamella is very wide. Herein this lectotype is illustrated in Figs. 3.20a, b, and 5.G, H.

Distribution. Off Heard Island, Southern Ocean (Indic Sector), 137m.

FIGURE 3. Occurrence of specimens previously recorded as Bairdoppilata simplex ( Brady, 1880) . Legend: — B. simplex ( Brady, 1880) ; —? B. labiata ( Müller, 1908) ; — B. cf. simplex (dubious records); * Bairdioidea spp. (misidentifications, surely not B. simplex ). Stations are numbered herein in alphabetical order of first author of the publications citing them (see table. 3, last column). The numbers related to the illustrated valves (all external view) indicate the station(s) (on the map) where they were collected, and consequently the author(s) who published this occurrence. 1– Brady (1880); 2– Brady (1890); 3–modified after Benson and Maddocks (1964, Pl.1.3, 1.6), 3a, LV, 3b, RV; 4– Briggs (1978); 5– Chapman (1902); 6–modified after Dingle (1993, Fig. 3.C, D), 6a, RV, 6b, LV; 7– Dingle (1995); 8–modified after Dingle (2000, Fig. 5 .C), RV; 9– Dingle et al. (1996); 10– Dingle and Giraudeau (1993); 11– Hartmann (1974), 11a– LV, ZMH K­30230, 11b–LV, ZMH K­30070; 12– Hartmann (1989), LV, ZMH K­33798; 13– Hartmann (1993), RV, ZMH K­ 35474; 14– Kaesler et al. (1979); 15– Maddocks (1969), RV, USNM 121347; 16– Maddocks (1969); 17– Maddocks (1969), 17a, LV, 17b, RV, USNM 121348; 18– Müller (1908); 19– Neale (1967); 20– lectotype of B. simplex designated by Puri and Hulings (1976), 20a, RV, 20b, LV; 21–modified after Whatley et al. (1995, Pl. 1.7, 1.8), 21a, LV, 21b, RV; 22– modified after Whatley et al. (1996, Pl. 1.33), RV; 23– Whatley et al. (1997a); 24–modified after Whatley et al. (1997b, Pl. 1.13), RV; 25–modified after Whatley et al. (1998b, Pl. 1.15), LV; 26–? Bairdoppilata sp. 2 aff.? B. labiata , ANDEEP III # 133–2–E (herein); 27–? Bairdoppilata sp. 1 aff.? B. labiata , ROSSMIZE, H in 4 (herein). Scale bar: 500 µm (applies to all valves illustrated).

Measurements ( Fig. 4 ). Lectotype: LV L 1.50mm, H 0.86mm; RV L 1.48mm, H 0.76mm.

Diagnosis (modified from Brady 1880; Puri and Hulings 1976). In lateral view, LV oblong, subovate, fairly equilateral, nearly twice as long as high, anterior and posterior margins rather narrow, evenly rounded; dorsal margin gently arched, ventral margin straight or slightly convex. RV equilateral, fairly subpentagonal. Anterior and posterior margins of both valves smooth (without denticles). Carapace compressed, ovate in dorsal view, about twice as long as broad, widest in the middle, extremities subacuminate. Shell surface smooth, with numerous open and evenly distributed radial pore canals. Zone of concrescence wide, vestibules well developed and widest at anterior end. Hinge terminal elements faintly denticulated. Marginal pore canals numerous, simple and straight.

Remarks. In the report on Ostracoda from the German South Polar Expedition, Müller (1908) described Nesidea labiata from the Gausstation (Indic Sector of the Southern Ocean, 385m depth) (see Fig. 3.18 herein). After studying the subfossil lectotype of Bairdoppilata simplex , and based on Müller’s published illustrations (1908, Pl. 14.1–5), Maddocks (1969: 77) considered N. labiata to be a junior synonym of B. simplex . On the contrary, after I studied the type material of B. simplex and N. labiata , I consider the second species as valid. The transference of N. labiata to the genus Bairdoppilata , as suggested by Maddocks (1969), is here considered dubious, since the diagnostic “4–6 tiny denticles on ends of right valve ridge articulating with sockets beneath left valve overlap” are not present in the types of N. labiata . No true hinge denticulation was observed in specimens of the Gausstation ( Fig. 6.C, D, F, J), in a few cases some kind of undulating structure was observed, but it was more likely due to an irregular relief on the hinge elements than to real teeth ( Fig. 6.A, G, L). Otherwise, the anterodistal seta of podomere VI of AII is enlarged, clawlike ( Figs. 8.A, C, 9.F), which is a diagnostic character of Bairdoppilata . For this reason, the assignment to the genus is considered dubious—? B. labiata ( Müller, 1908) . The differences observed between the lectotype of B. simplex (Figs. 3.20a, b, 5.G, H) and types of? B. labiata are described below.

(1) The most conspicuous features that differentiate B. simplex ( Fig. 5 .G, H) from? B. labiata ( Fig. 5 .A–D, I–K) are the more arcuate dorsal margin and more broadly rounded posterior margin of the latter species. These differences are not due to sexual dimorphism since both sexes from N. labiata present these characteristics.

(2) Also conspicuous is the difference in dorsal view:? B. labiata presents very inflated, subhexagonal shape ( Fig. 7.N), while B. simplex is more elongate, less wide ( Brady, 1880, Fig.b, c).

(3) The hinge denticulation of B. simplex is conspicuous even under an optic microscope, while in? B. labiata it is very faint, if not absent, even under electron microscopic magnifications ( Fig. 6.A, C, D, F, G, J, L).

(4) RV in both species present tri­segmented dorsal margin, but in B. simplex it is more rounded, with inconspicuous posterodorsal angle ( Fig. 5 .A, C, G).

Maddocks (1969) also assigned to B. simplex specimens from three other localities in the Southern Ocean, and dubiously assigned to B. simplex subfossil specimens from the Southeastern Atlantic. Part of this was restudied herein, one male (USNM 121348, from the Pacific Sector of the Southern Ocean) and one female (USNM 121347, from the Atlantic Sector of the Southern Ocean), and the differences between B. simplex and? B. labiata (described above) could also be observed between B. simplex and these 2 last specimens, which are herein identified as Bairdoppilata sp. 1 aff.? B. labiata ( Müller, 1908) (see below).

The RV from off Antarctic Peninsula (Fig. 3.13 herein) recorded by Hartmann (1993) as B. simplex was re­studied and illustrated herein, see below? Bairdoppilata sp. 4, and is considered a misidentification. Hartmann’s specimen is most probably an adult (see the very wide calcified inner lamella in Fig 15.P), which presents a similar shape to the lectotype of B. simplex , but which is much smaller—length 0.84mm, instead of 1.50mm.

Based on the published illustrations, the specimens “AM/4, AM/1, AM/2” from the Malvinas Island identified as B. sp. cf. B. simplex ( Whatley et al. 1995, Pl. 1.7–12) are not co­specific to B. simplex . The following differences between Whatley’s material and the lectotype of B. simplex are: RV mid­height anterior to midlength, instead of at mid­length; and LV with rounded posterodorsal margin (Fig. 3.20a, b), the carapace is more elongate, less wide in dorsal view.

Dingle’s (2000) illustrated RV, from the Quaternary of Victoria Land Basin, Antarctica, is similar to the lectotype of B. simplex , but could also be co­specific to? B. labiata or other bairdioid species.

Other specimens assigned to B. simplex (Dingle 1993, Whatley et al. 1996, 1997, 1998b) should be included in other bairdiid species and genera (Fig. 3.3, 3.6, 3.21, 3.22, 3.24, 3.25). Some of these specimens present a more globose form and comprise at least 4 different species: (1) from the Halley Bay, Antarctic Peninsula ( Whatley et al., 1998b) (Fig. 3.25 herein); (2) off South Georgia, Scotia Sea ( Hartmann 1989), (see Bairdoppilata sp. 3 herein, Figs. 3.12, 15.A–G); (3) from Knysna Estuary, Namibia (“ Bairdia villosa ? Brady, 1880 ” from Benson & Maddocks 1964, assigned to B. simplex by Dingle 1993) (Fig. 3.3 herein); (4) in Lüderitz Bay, South Africa (part of Bairdoppilata sp. 44 from Hartmann 1974, assigned to B. simplex by Dingle 1993, identified herein as Bairdoppilata sp. 5) (Figs. 3.11a and 16); (4) Simon’s Bay, South Africa (“ Bairdia ovata Bosquet, 1853 ” from Brady 1880 assigned to B. simplex by Dingle 1993). Other specimens assigned to B. simplex present a more angulated outline and occur (1) off South Africa and Namibia (Dingle 1993) (Fig. 3.6 herein), part of Bairdoppilata sp. 44 from Hartmann (1974) (assigned to B. simplex by Dingle 1993 and herein identified as Bairdoppilata sp. 6 (Figs. 3.11b); (2) Straight of Magellan ( Whatley et al., 1996) (Fig. 3.22 herein). Other misidentifications of B. simplex include specimens with RV higher anteriorly, instead of higher at mid­length; and RV with rounded posterodorsal margin ( Whatley et al. 1995) (Fig. 3.21 herein). Also, the records from the warm water littoral of Fiji, SW Pacific ( Brady 1890) are very improbable.

Figures

FIGURE 4. Length: height scatter plot of the valves of specimens previously recorded as Bairdoppilata simplex (Brady, 1880) (including all misidentifications). Legend: Measurements taken from: B. simplex – lectotype of B. simplex; B. labiata – lecto­ and paralectotypes; B. aff. 1 – B. sp. 1 aff. B labiata (as identified herein); B. aff. 2 – B. sp. 2 aff. B labiata (as identified herein); B. spp. – all other misidentifications of B. simplex (Dingle 1993; Neale 1967; Maddocks 1969; Hartmann 1989; Hartmann 1993; Whatley et al. 1995, 1996, 1997 a; Whatley et al. 1998 b).

FIGURE 5.? Bairdoppilata. labiata (Müller, 1908), B. simplex (Brady, 1880),? B. sp. 1 aff.? B. labiata, and? B. sp. 2 aff.? B. labiata. Legend:? B. labiata (Müller, 1908): A, B, A M (lectotype, ZMB 13069, SNB 0683); C, D, A M, K, A F (subfossil paralectotypes, ZMB 13069); I, J, A F (paralectotype, ZMB 13069, SNB 0682).? B. sp. 1 aff.? B. labiata: E, F, A M (USNM 121348); N, A F (USNM 121347). B. simplex (Brady, 1880): G, H, lectotype (BMNH cat. no. 81.5.13).? B. sp. 2 aff.? B. labiata: L, M, A F (ZMH K­ 41359, SNB 0386). A, C, E, G, I, L, N, RV, ev; B, D, F, H, J, K, M, LV, ev. Scale bars: 500 µm.