Bairdoppilata simplex
(modified by Brandão, 2008 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.
Bairdoppilata simplex is very similar to ?Bairdoppilata labiata (Müller, 1908) (see remarks for details).
Lectotype: LV L 1.50mm, H 0.86mm; RV L 1.48mm, H 0.76mm.
See remarks.
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 lectotype and described by Puri & Hulings (1976, p. 266, Pl. 3.11–13), also examined by Maddocks (1969, p. 77) and Brandão (2008, p. 379-382, Figs. 3.20a, b, and 5.G, H) . This specimen is probably an adult since the calcified inner lamella is very wide.
H, Height; L, length; LV, left valve; RV, right valve.
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.
2008 Bairdoppilata simplex, Brandão: 379-382, Figs. 3.20a, b, 5.G, H, Tab. 3.
<p>Bairdoppilata simplex is one of the species described by Brady (1880) which was subsequently recorded from many distant localities, in this specific case, from the Southern Hemisphere (Fig. 1), including the Pacific (Brady 1890, Chapman 1902), the Atlantic (Eastern: Dingle 2003; and Western: Whatley et al. 1995, 1996, 1997a), and the Southern oceans (Brady 1880, Dingle 2000, Hartmann 1989, 1993, 1997, Maddocks 1969, Neale 1967, Whatley et al. 1998b). Several of these records obviously do not involve the species B. simplex and also involve other bairdioid genera (Brandão, 2008, Fig. 3.3, 3.6, 3.11b, 3.12, 3.22, 3.24). This is the case, for example, of the specimens from the “Gausstation” (Indic Sector of the Southern Ocean, 385m), which were described by Müller (1908) as Nesidea labiata, and later considered a junior synonym of B. simplex (Maddocks 1969: 77). The re-study of part of the specimens previously assigned to B. simplex shows that more than ten different species are represented (see below), and that B. simplex is restricted to its type locality (off Heard Island).</p> <p>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. 1.18 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 Brandão (2008) studied the type material of B. simplex and N. labiata, she 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, 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. Otherwise, the anterodistal seta of podomere VI of the antenna II is enlarged, clawlike, which is a diagnostic character of Bairdoppilata. For this reason, the assignment to the genus was considered dubious—?B. labiata (Müller, 1908). The differences observed between the lectotype of B. simplex and types of ?B. labiata are described below.</p> <p>(1) The most conspicuous features that differentiate B. simplex from ?B. labiata 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.</p> <p>(2) Also conspicuous is the difference in dorsal view: ?B. labiata presents very inflated, subhexagonal shape, while B. simplex is more elongate, less wide (Brady, 1880, Fig.b, c).</p> <p>(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.</p> <p>(4) RV in both species present tri-segmented dorsal margin, but in B. simplex it is more rounded, with inconspicuous posterodorsal angle.</p> <p> 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 were herein identified by Brandão (2008) as Bairdoppilata sp. 1 aff. ?B. labiata (Müller, 1908). The RV from off Antarctic Peninsula recorded by Hartmann (1993) as B. simplex was re-studied and illustrated by Brandão (2008) and identified as?Bairdoppilata sp. 4, and was considered a misidentification. Hartmann’s specimen is most probably an adult (because of its very wide calcified inner lamella), 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 co-specific to B. simplex. The following differences between Whatley’s material and the lectotype of B. simplex are: RV mid-height anterior to midlength, instead of at mid-length; and LV with rounded posterodorsal margin (Fig. 1.20a, 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 co-specific 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. 1.3, 1.6, 1.21, 1.22, 1.24, 1.25). 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. 1.25 herein); (2) off South Georgia, Scotia Sea (Hartmann 1989), (see Bairdoppilata sp. 3 herein, Figs. 1.12); (3) from Knysna Estuary, Namibia (“Bairdia villosa? Brady, 1880” from Benson & Maddocks 1964, assigned to B. simplex by Dingle 1993) (Fig. 1.3 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. 1.11a); (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. 1.6 herein), part of Bairdoppilata sp. 44 from Hartmann (1974) (assigned to B. simplex by Dingle 1993 and herein identified as Bairdoppilata sp. 6 (Fig. 1.11b); (2) Straight of Magellan (Whatley et al., 1996) (Fig. 1.22 herein). Other misidentifications of B. simplex include specimens with RV higher anteriorly, instead of higher at mid-length; and RV with rounded posterodorsal margin (Whatley et al. 1995) (Fig. 1.21 herein). Also, the records from the warm water littoral of Fiji, SW Pacific (Brady 1890) are very improbable.</p>.
Recent (collected as subfossil (=empty valves)). Off Heard Island, Indic Sector of the Southern Ocean, 137m.
See remarks for a discussion on previous records of Bairdoppilata simplex in other regions.
Brandão, S. 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: 373–452.
(this publication can be freely downloaded from http://www.mapress.com/zootaxa/2008/f/zt01866p452.pdf)