Bairdoppilata labiata Muller 1908

? Bairdoppilata labiata (Müller, 1908)

(Figs. 3.18, 4, 5.A–D, I–K, 6, 7, 8.A, C, F, G, J, M–O, R, T, 9.A–F)

1908 Nesidea labiata Müller: 99, Fig. 1.a–d.

1967?non Nesidea labiata, Neale: 5, 6.

1997 in part Bairdoppilata (Bairdoppilata) simplex, Hartmann: 47, Fig. 11.a–c, e–g. 2000?non Bairdoppilata cf. B. simplex, Dingle: 486.

Material. Previously the syntype series used by Müller to describe “ Nesidea labiata ” were in a glass containing alcohol and labelled “ Nesidea labiata G. W. Müller, Gaus Station (177a), 385m, Deut. Südpolar Exp., 1901–1903, ZMB 13069”. Inside of this larger glass there were six small vials labeled “177a­1.03”, “177a­ 2.03”, “177a­4.02”, “177a­6.02”, “177a­10.02a”, and “177a­12.02” (see below). These labels most probably indicate the date of collection of each sample, since Müller (1908) stated that these samples were collected between March 1902 and February 1903, and that N. labiata was especially abundant in December. The vial labelled “177a­12.02” is the one with the largest number of specimens. Finally, three more glass slides with valves and dissected soft parts also form part of Müller’s syntype series.

Lectotype (herein designated with the purpose of clarifying the application of the name ? B. labiata to the taxon): 1 dissected A M (SNB 0683), soft parts on glass slides with permanent medium “Hydromatrix” and 2 valves on a micropaleontological slide, ZMB 13069. Previously this specimen was in a vial containing alcohol and labelled “ Nesidea labiata G. W. Müller, Gaus Station (177a.12.02), 385m, Deut. Südpolar Exp., 1901– 1903, ZMB 13069”. A newly dissected specimen was chosen as the lectotype, since the three slides containing the specimens dissected and illustrated by Müller (1908) can not be observed under the higher magnification objective (100X) of an optical microscope because of the large quantity of preserving medium. Furthermore, the valves of these 3 specimens were also preserved in permanent medium (which contain cracks) on glass slide, being impossible to study them accurately.

Paralectotypes: 58 *live specimens preserved in alcohol, 7 RV, 11 LV on micropaleontological slides. All these specimens were in six small vials (see below) and three slides:

*Part of the material listed below as live A, (A­1), (A­2), (A­3), (A­4), (A­5) might or might not contain soft parts, since all the valves from the Gausstation were opaque, it was not possible to be sure if some specimens were live or subfossil.

1) Vial labelled “177a­4.02”—subfossil: 2 A RV, 1 (A­4) RV, 1 A LV, 1 (A­1) LV.

2) Vial labelled “177a­6.02”—*live: 1 A F, 1 (A­1); subfossil: 1 A RV, 1 A LV.

3) Vial labelled “177a­10.02a”—*live: 4 (A­1), 1 (A­4) (one of them dissected SNB 0686).

4) Vial labelled “177a­12.02”—*live: 9 A F (one of them dissected SNB 0682), 9 A M, 5 (A­1) F (one of them dissected SNB 0685), 6 (A­2), 1 (A­3), 9 (A­4), 1 (A­5); subfossil: 1 A RV, 1 (A­2) RV, 4 A LV, 3 (A­1) LV, 1 (A­2) LV.

5) Vial labelled “177a­1.03”—*live: 1 A, 4 (A­1), 1 (A­4); subfossil: 1 (A­4) RV.

6) Vial labelled “177a­2.03”—*live: 1 (A­2), 1 (A­4).

7) 1 glass slide with permanent medium containing appendages and 2 valves of 1 A M, and labelled “ Nesidea labiata, 1672, Gauss., 177a­12.02, 1 adult male”.

8) 1 glass slide with permanent medium containing appendages and 2 valves of 1 A M, and labelled “ Nesidea labiata, 1674, Gauss., 177a­12.02, 1 adult male”.

9) 1 glass slide with permanent medium containing appendages and 2 valves of 1 A F, plus one closed carapace positioned in dorsal view, and labelled “ Nesidea labiata, 1680, Gauss., 177a­12.02, 1 adult female”.

Distribution. Known only from the type locality, Southern Ocean (Indic Sector), 385m.

Measurements (Fig. 4). Lectotype, LV, L 1.52mm (with spines and fringe) 1.50mm (without spines and fringe), H 0.93mm RV, L 1.61mm (with spines and fringe) 1.53mm (without spines and fringe), H 0.87mm.

Paralectotypes, LV, A L 1.64–1.83mm, H 0.94–1.10mm; (A­1) L 1.32–1.39mm, H 0.80–0.84mm; (A­2) L 1.00– 1.08mm, H 0.62–0.68mm; (A­3) L 0.80mm, H 0.50mm; (A­4) L 0.60­0.64mm, H 0.38–0.40mm; (A­ 5) L 0.49mm, H 0.30mm.

Diagnosis. LV and RV subtriangular, smoothly rounded, equilateral in female, fairly inaequilateral in male, not caudate in lateral view. Valve surface of adults and juveniles smooth. Hinge anterior and posterior elements without visible teeth. Carapace subhexagonal, very inflated medially in dorsal view. Podomere VI of AII with 1 medium­sized anterodistal claw, 1 long posterodistal claw, 2 small setae, and 1 medium­sized, fused seta. Fu with 7 setae; setae 2 and 4 longest. Genital lobe oval, with very long and tightly coiled internal tube, and an external elongated process. Hemipenis with subrectangular basal element, subhemispherical medial element, and elongated distal element, the last one terminates in a finger­like process; copulatory tube very elongate and strongly sclerotized; an elongated, flattened process arises from the distal part of medial element.

Description. LV and RV subtriangular, smoothly rounded, equilateral in female, fairly inaequilateral in male, not caudate in lateral view. Males tend to be not as long, and not as high as females. Valve surface of adults smooth. Valves of adults and juveniles covered by many conspicuous sensilla of variable length, from very short to very long; long sensilla barbed. Normal pore canals simple, with narrow rims or without rim. Anterior fringes and posterior marginal denticles well developed. Marginal pore canals long and straight, not very numerous. Calcified inner lamella medium­sized. Hinge anterior and posterior elements with or without very faint denticulation, medial bar finely striate. Carapace subhexagonal, very inflated in dorsal view, with rounded contour, maximum width at mid­length. Eight adductor muscle scars present.

AI with several very long setae; chaetotaxy 1(0/0), 2(.1/0), 3(.1/0), 4(.1/.1), 5(.2/.2), 6(.2/.2.), 7(0/0:3). AII with elongated podomere IV and V; exopodite with 1 very long and 2 short setae; podomere VI with 1 medium­sized anterodistal claw (its length about ¾ that of posterodistal claw), 1 long posterodistal claw, 2 small setae, and 1 medium­sized, fused seta in males; females present a more robust fused seta (claw­like); chaetotaxy 1(0/0: 2i), 2(.1/0: 1i), 3(0/.3.2), 4(0/.2), 5(.1.2./.1,1), 6[male:(0/0:1c,1c,1,1fs); female:(0/ 0:1c,1c,2,1fc)]. Masticatory process of Md with several setae, and 1 simple, plus 5 trifurcate, plus 1 bifurcate teeth; exopodite with 1 very long and 2 long setae; podomere IV palp with 1 robust, feathered, distal claw; chaetotaxy of palp 1(0/.1.: 1i), 2(.2/.2: 1i), 3(.4./.1: 2i), 4(.1./3pc,2). Vibratory plate of MxI with 6 subequal strahlen and 25 feathered setae; endites with modified, broad, feathered, distal claws, and also simple setae and claws; chaetotaxy of palp (.3./1:1,1pc). Vibratory plate of ApV with 4 proximally segregated strahlen, and 13 feathered setae, chaetotaxy 1(.1.2. 2­3. 1/0), 2(.2/0), 3(.1/0), 4(0/0:1r,1c). Chaetotaxy of Ap VI and VII 1 (.1.1.1.1/0), Exopodite(0/0:2), 2(2/0), 3(.1/0), 4(.1/0), 5(0/0:1r,1c). Fu with 7 setae; seta 1 (more distal one) thick, seta 2 the longest and distally feathered; seta 4 also long, other setae short, but not vestigial. Brushshaped organ assymetrical. Genital lobe oval, with very long and tightly coiled internal tube and an external elongated process. Hemipenis with subrectangular basal element, followed by a medial subhemispherical element and terminated by an elongated, irregularly shaped distal element, the last terminates in a finger­like process; copulatory tube very elongate and strongly sclerotized; an elongated, flattened process arises from the distal part of the medial element.

Remarks. The differences between ? B. labiata and B. simplex are presented in the Remarks of the last species.

The juvenile LV recorded by Neale (1967, Fig. 2) from the Halley Bay, Antarctic Peninsula, presents a more broadly rounded posterior margin. Consequently this record is herein considered dubious.

Dingle’s (2000) illustrated RV (identified as B. simplex), 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.