Bathycalanus tumidus, Bradford-Grieve, Janet M., Blanco-Bercial, Leocadio & Boxshall, Geoffrey A., 2017

Bradford-Grieve, Janet M., Blanco-Bercial, Leocadio & Boxshall, Geoffrey A., 2017, Revision of Family Megacalanidae (Copepoda: Calanoida), Zootaxa 4229 (1), pp. 1-183 : 108

Bathycalanus tumidus n. sp.

( Figs 46 , 67–70 )

Type locality. 29.5333o N, 137.233o E.

Material examined. Antipode IV, IKMT: Stn 52D, 0–1900 m, 1♀ (10.9 mm) holotype; Stn 53A, 0–2000 m, 2♀ (10.0, 10.5 mm) paratype; Stn 53D, 0–2500 m, 1♀ (10.2 mm). ANTXIV/1, MOC10, Stn 2, 2000–3000 m, 1♀ (9.5 mm) Co375.1.1, 1♀ (9.3 mm) Co375.1.3, paratype. MV 73-I, IKMT, Stn 53, 0–2000 m, 1♀ (10.4 mm).

Type specimens. Deposited in the collection of the Scripps Institution of Oceanography, California. Holotype female: PIC- 140409 - 0012-HT; Paratype series: PIC- 140409 -0013-PT. Deposited in the collection of the National Institute of Water and Atmospheric Research , Wellington: NIWA 85230 (Co375.1.3) 1 vial plus 1 slide.

Genetic material. Co375.1.1, Co375.1.3. GenBank numbers in Table 6.

Morphological description. Following description based on holotype specimen from Antipode IV Stn 52D. As for genus with following additional specific level features.

Female ( Fig. 67 A–F). Total length 10.6 mm (mean = 10.11 mm, range = 9.3–10.9 mm, n = 7). Anterior margin of head, in dorsal view, produced into distinct short rounded projection located dorsal to base of rostrum and bearing pair of small stout divergent spine-like processes. In lateral view, posterolateral corners of pedigerous somite 5 symmetrical, rounded. Genital double-somite bulbous, symmetrical in dorsal view, slightly wider than long, widest width at approximately midlength, with small anteroventral genital operculum, seminal receptacles not observed.

Antennule ( Figs 67 F, 68) lengths of antennule segments (µm) as follows. Measurements taken along posterior border of each segment but two (posterior (shortest) and anterior) measurements taken of ancestral segment I. I (327, 644); II– IV (478); V (268); VI (288); VII (673); VIII (384); IX (357); X–XI (587); XII (406); XIII (406); XIV (495); XV (618); XVI (692); XVII (766); XVIII (819); XIX (878); XX (951); XXI (998); XXII (760); XXIII (703); XXIV (782); XXV (772); XXVI (372); XXVII (-); XXVIII (-). Anterior and posterior borders of antennule ancestral segments XVI–XXI smooth.

Antenna ( Fig. 69 A) exopod segment IV with short seta extending beyond distal border of segment VIII and bearing short setules.

Maxillule ( Fig. 69 C) praecoxal arthrite with 15 setae including 4 on posterior surface and 2 small anterior surface setae; coxal endite with 1 seta, basal endites 1 and 2 with 2 and 4 setae respectively, basis and endopod segments 1 and 2 fused although demarcation between segments visible, segment 3 separate; endopod segments with 2 (subequal), 2 (subequal), 5+1 smaller anterior surface seta.

Maxilliped ( Fig. 69 E) syncoxal endite 4 with large toothed seta extending half way along endopod segment 2.

Leg 1 ( Fig. 67 G) exopod with articulation between exopod segments 2 and 3 well developed.

Male. Unknown.

Distribution. Bathycalanus tumidus n. sp. is an upper abyssopelagic species taken in the eastern and western North Pacific and the Atlantic off West Africa near the Cape Verde Islands where it was found at depths between 2000 and 3000 m ( Fig. 46 , Table 1 ).

Species comparisons. This species is very like Ba. richardi except the genital double-somite is of a bulbous shape in dorsal view, widest at midlength and wider than long. The maxillule praecoxal arthrite has 4 posterior surface setae, unlike any other species of Bathycalanus ; the coxal endite has one relatively well-developed seta unlike most other known Bathycalanus except Ba. pustulosus n. sp.; and basal endite 2 has 4 setae whereas in Ba. pustulosus it has only 2 setae ( Table 10 ). The genetic distance data suggest that this species may represent an as yet unrecognised genus (see Tables 14–17).

Etymology. The species name is derived from the Latin adjective “ tumidus ” meaning swollen, referring to the shaped of the genital double-somite.

Figures

FIGURE 46. Distribution of Bathycalanus species: filled triangle = Bathycalanus bradyi; open triangle = Ba. milleri n. sp.; filled square = Ba. richardi; open square = Ba. dentatus n. sp.; open circle = Ba. tumidus n. sp.; open diamond = Ba. adornatus n. sp.; filled star = Ba. pustulosus; filled diamond = Ba. unicornis; filled circle = Ba. bucklinae n. sp.; cross = Ba. eximius.

FIGURE 67. Bathycalanus tumidus n. sp. female: A, dorsal view; B, dorsal view of anterior head; C, lateral view of anterior head; D, dorsal view of urosome; E, lateral view of genital double-somite; F, antennule; G, posterior view of leg 1. Scale bar represents 1.0 mm on all figures. Illustrated specimen from Antipode IV, Stn 52 D.

FIGURE 68. Bathycalanus tumidus n. sp. female antennule ancestral segments: A, segments I – XIV; B, segments XV – XVIII; C, segments XIX – XXII; D, segments XXIII – XXVI; E, segments XXVII – XXVIII; F, detail of segment XXVIII. Scale bar represents 1.0 mm on figures A – E; 0.1 mm on remaining figure. Illustrated specimen from Antipode IV, Stn 52 D.

FIGURE 69. Bathycalanus tumidus n. sp. female: A, antenna; B, mandibular palp; C, maxillule; D, maxilla; E, maxilliped. Scale bar represents 1.0 mm on figures D, E; 0.1 mm on remaining figures. Illustrated specimen from Antipode IV, Stn 52 D.

FIGURE 70. Bathycalanus tumidus n. sp. female: A, anterior view of leg 2; B, anterior view of leg 3; C, anterior view of leg 4; D, posterior view of leg 5. Scale bar represents 1.0 mm on all figures. Illustrated specimen from Antipode IV, Stn 52 D.