Zygophylax infundibulum Millard 1958

Zygophylax infundibulum Millard, 1958

Plate 4 A–F

Zygophylax infundibulum Millard, 1958: 180–181, fig. 4b–c; Millard, 1968: 266; Millard, 1973: 32; Millard, 1975: 197–198, fig. 65d–e; Millard, 1978: 200; Millard, 1979: 140; Millard, 1980: 131, 143–144, fig. 4d; Rees & Vervoort, 1987: 84; Calder & Vervoort, 1998: 28; Vervoort & Watson, 2003: 69; Miranda et al., 2015: 506.

Type Series. Holotype—Several stems and two whole mounts, without gonophores (SAM H36) (Millard, 1979).

Type Locality. Coll. Pieter Faure, St. 10781, Natal coast, Durban, South Africa, 29°53’S 31°11’E, 155 m, 17 December 1900.

Material examined. Coll. T. Mortensen Exp. 1929, St. 24, near Durban coast, South Africa, 29°48’30’’S 31°18’E, 219 m, 22 August 1929, det. N.H.A. Millard, small colonial fragments, without gonophores (ZMUC-HYD 271); Coll. Benthedi, St. S 93, Indian Ocean, off northern Madagascar, 11°32.3’S 47°16’E, 400–556 m, 07 April 1977, without gonophores (RMNH-Coel. slide 253); Coll. Marion Dufresne, St. FA 117, as Z. cf. infundibulum, La Réunion, 20°57’S 54°08’E, 470–540 m, 31 August 1982, without gonophores (RMNH-Coel. slide 261).

Description of additional material. (ZMUC-HYD 271) Stem rectilineous, mostly polysiphonic with only distamost part monosiphonic, not divided into nodes; hydrothecae facing one side of the colony. Hydrocladia polysiphonic proximally and monosiphonic distally (Pl. 4A), divided into transversal nodes, each internode with three hydrothecae; hydrocladia with axillary hydrotheca on axial apophyses, with subopposite arrangement, planar; hydrothecal apophyses developed, separated from hydrocladia by septum and constricton of perisarc. Hydrothecae tubular, slightly sigmoid, adcauline wall concave under rim, abcauline wall convex (Pl. 4C–D), pedicel long, rectilineous, slightly wrinkled (Pl. 4B), diaphragm thick, convex. Nematothecae tubular on hydrothecal apophysis (Pl. 4E–F).

Measurements. Stem: distance between two subsequent hydrothecae 156–390 µm; diameter 182–442 µm; distance between subsequent hydrocladia at the same side 1.7–1.8 mm. Hydrocladia: lenght 5.1–7.4 mm; diameter at base 130–156 µm. Hydrothecae: length of adcauline wall from rim to diaphragm 350–370 µm; lenght from base budding of the axis to rim 540–610 µm; diameter at rim 130–150 µm; diameter at diaphragm 70 µm; diameter of pedicel on adcauline side 240–270 µm; diameter at apophysis 50 µm. Nematothecae: lenght 40–160 µm; diameter at rim 20–30 µm.

Diagnosis of reproductive structures. “Gonothecae not adpressed, narrow at base and widening distally, then divided into two outwardly curved necks bearing the terminal apertures. Protective tubular structures numerous, arising amongst the gonothecae and rising above them, completely obscuring them and forming a bristly coat to the coppinia; each branching irregularly and bearing many nematothecae similar to those to the trophosome. Each gonothecae apparently arising from the base of one of the tubular structures” (Millard, 1980: 143–144).

Geographical distribution. southern Brazil (Miranda et al., 2015); off Natal, South Africa, 115–219 m (Millard, 1975); off northern Madagascar, 400–556 m (present study).

Remarks. Zygophylax infundibulum Millard, 1958 is known from the Indian coast of South Africa (Millard, 1958, 1975, 1979, 1980), recently also recorded for Brazil by (Miranda et al., 2015) and now for Madagascar (this study). The gonosome of the species was subsequently described (Millard, 1980). We did not have access to any of the materials deposited in the South African Museum (SAM). The species may be diagnosed by the triangular shape of gonothecae with two short projections with apertures, the coppinia with numerous protective tubes, the hydrothecae curved at the distamost third and facing one side of the colony, and the long pedicels on well-demarcated apophyses.

Zygophylax infundibulum has similarities with Z. unilateralis, such as the sigmoid hydrothecae, hydrothecae oriented towards one side of the colony, distinct apophyses, non-adnate elongated gonothecae widening basally, and the many protective tubes in the coppinia. However, Z. unilateralis differs by the larger and thicker hydrothecae, globular to bi or trilobate nematothecae on hydrothecal apophyses, hydrocladia and secondary axial tubes, pedicel varying from totally smooth to slightly wrinkled or even segmented throughout its extension (e.g., in the holotype BMNH 29.10.28.77), and the 2–3 processes in the gonothecae of Z. unilateralis.

Millard (1980) also reported trophosomal and gonosomal similarities between Z. infundibulum and Zygophylax sibogae Billard, 1918, like the curved hydrothecae resembles of Z. infundibulum similar to those of young colonies of Z. sibogae (e.g., RMNH-Coel. slide 258), the shape of the gonothecae, and of the high density of protective tubes in the coppinia, although Z. sibogae has more elongated projections facing to opposite directions. Other characters listed above also help to differentiate between the species.

Colonies of Z. infundibulum undertake regeneration processes leading to the segmentation of the apophyses, the pedicels or even the hydrothecae, by the duplication of the diaphragms (Millard, 1958). We observed pedicels slightly segmented or wrinkled in some specimens (ZMUC-HYD 271, South Africa; RMNH-Coel. slide 253, Madagascar). This regeneration process and the resulted pedicelar annulations differ from those of Z. naomiae sp. nov. (see above). In the same specimen, regeneration processes also alter the number of renovations on rim (up to 11), increasing significantly the length, as well as the nematothecae of the secondary axial tubes of the stem vary from tubular to extremely thin and elongated, with a widened apex with one aperture.