Bythopussella aculeata Muller 1908

Bythopussella aculeata (Müller, 1908)

(Figs. 43, 45.P–S)

1908 Anchistrocheles aculeata Müller: 100–102, Pl. 14.7–14, Pl. 15.1–5. 1969 non Anchistrocheles? sp. aff. A. aculeata, Maddocks: 113, Fig. 60m. 1990 Anchistrocheles aculeata, Warne: 114.

1997 Anchistrocheles? aculeata, Hartmann: 55, Fig. 16.

Material. Since B. aculeata is the type species of the genus Bythopussella, I prefer not to designate a lectotype for B. aculeata, because the 5 adult specimens available are in very bad conditions (fragmented soft parts and valves). I think that the designation of a lectotype should be done when new material (in good condition) is available.

The syntype series of B. aculeata includes one glass containing specimens in alcohol and labelled “ Anchistrocheles aculeata Müller, Gauss­Station, 385m, Deut. Südpolar Exp., 1902­1903, ZMB 13086”:

1) This vial contained seven juveniles with completely decalcified valves – 6 (A­1), 1 (A­2). Additionally, four glass slides with dissected specimens and valves also form part of Müller’s syntype series:

2) Glass slide with permanent medium containing appendages, 1 RV and pieces of LV of 1 A F, and labelled “ Anchistrocheles aculeata, 1649, Gauss., 177b female, 11.02”.

3) Glass slide with permanent medium containing very fragmented appendages, 1 RV and pieces of LV of 1 A M, and labelled “ Anchistrocheles aculeata, 1652, Gauss., 177b male, 12.02”.

4) Glass slide with permanent medium containing very fragmented appendages, 1 RV and pieces of LV of 1 A M, and labelled “ Anchistrocheles aculeata, 1662, Gauss., 177b male, 12.02”.

5) Glass slide with permanent medium containing fragmented appendages, 1 LV and pieces of RV of 1 juvenile?, plus one RLV positioned in dorsal view, and labelled “ Anchistrocheles aculeata, 1677, Gauss., 177b, 1.03”.

Other specimens studied herein were in the vial of the types of Bairdoppilata labiata (ZMB 13069):

6) 1 A M (dissected by myself, SNB 0687), and 1 (A­2) were previously together with the type series of Bairdoppilta labiata (Müller, 1908), in the vial labelled “ Nesidea labiata G. W. Müller, Gaus Station (177a), 385m, Deut. Südpolar Exp., 1901­1903, ZMB 13069, 177a ­ 12.02”. The adult male specimen is herein illustrated (Fig. 45.P–S);

7) 1 (A­2) in vial labelled were previously together with the type series of Bairdoppilta labiata (Müller, 1908), in the vial labelled “ Nesidea labiata G. W. Müller, Gaus Station (177a), 385m, Deut. Südpolar Exp., 1901­1903, ZMB 13069, 177a – 1.03”.

Distribution. Only known from the type locality, Southern Ocean (Indic Sector), 385m.

Measurements. Syntypes: LV, A M (SNB 0657) L 0.94mm, H 0.54mm; (A­1) L 0.84mm, H 0.48mm; (A­ 2) L 0.63mm, H 0.40mm.

Diagnosis. Valves fairly large, bairdiid in aspect, with conspicuous lateral punctation in the central area of lateral surface (anterior and posterior are smooth); both valves with small spines on anterior margin; LV with 1 medium­sized spine on posterior margin. AII with elongate, slender podomeres; podomere VI with 1 long claw, and 1 medium­sized and 1 small setae in males and females. MxI with 7 strahlen. ApV robust.

Podomere V of ApV to VII with 1 long terminal claw, and one vestigial seta. Fu with 1 large and 1 mediumsized claws, and 2 medium­sized setae. Genital lobe subcircular with short, internal tube. Hemipenis with elongated/sub­hemispherical basal capsule, which presents a beaked­shaped distal part; short, fairly straight copulatory tube, and one rigid, chitinized, short, medial process.

Remarks. Details in chaetotaxy could not be studied in B. aculeata since all adults dissected and are preserved in a large quantity of permanent medium, which impedes their observation under the larger microscope objective magnification (100X).