Plumularia gaimardi ( Lamouroux, 1824 )

Schuchert, Peter, 2013, The status of Plumularia lagenifera Allman, 1885 (Cnidaria, Hydrozoa) and related species, Zootaxa 3613 (2), pp. 101-124 : 122

Plumularia gaimardi ( Lamouroux, 1824)

Figs 12A–D , 13A–G , 14 A–D

Aglaophenia Gaimardi Lamouroux, 1824: 611 , pl. 95 figs. 9–10.

not Plumularia Gaimardi. – Kirchenpauer, 1876: 27, pl.1 fig 6, pl. 3 fig 6.

Plumularia lagenifera var. septifera . – Ritchie 1909: 65, fig. 7a–b.

[not Plumularia lagenifera var. septifera Torrey, 1902 ]

Plumularia setacea var. gaimardi . – Billard 1909: 325, fig. 10.

Plumularia lagenifera . – Broch 1914: 26. – Millard 1957: 230. – Millard 1962: 300. – Millard 1975: 392, fig. 124A–D.

[not Plumularia lagenifera Allman, 1885 ]

Material examined. See table 1. Note that the sample SAM-H-2230 contained two separate colonies, one female on red algae (2230A, with deep hydrothecae) and one male (2230B, shallow hydrothecae) on a laminarian algae. Additionally the sample contained isolated plumes of a female with short hydrothecae and isolated male plumes with deep hydrothecae. These isolated plumes are potentially contaminations from other samples.

Description. As P. setacea described above but abcauline walls of hydrotheca always distinctly convex, always thick-walled or with thickening near rim, intrasegmental perisarc thickenings regularly present. Plume heights 6–30 mm, occasionally also branched. Only one nematotheca on apophyses of stem segments. Stolons in colonies on laminarians band-like with internal ridges, or hydrorhiza coalesced to plate, often with large nematothecae. Colonies always gonochoristic. Female gonothecae paddle-shaped with neck that is often recurved. Male gonotheca spindle or paddle-shaped, with or without neck.

Dimensions. See table 1.

Type locality. Cape of Good Hope , on macroalgae .

Distribution. Endemic to South Africa.

Remarks. As discussed above, hydroids of South African P. lagenifera sensu Millard (1975) are here referred to P. gaimardi .

Plumularia gaimardi has rather frequently large nematothecae on the stolons ( Fig. 14C ). However, this is not a unique feature as it is also found in P.setacea and P. lagenifera (observations made on material used for this study).

In the form with shallow hydrothecae ( Fig. 12 , rows A and B), a series of desmocytes near the base of the hydrotheca is frequently visible ( Fig. 12B 2 , 12B 3 ). These desmocytes are sometimes rather indistinct or very close to the hydrothecal base and thus difficult to observe. They are, however, not a unique feature of this species as they can also be present in P. setacea , although they are usually indistinct and close to the bottom of the hydrotheca, thus very difficult to observe.

Figures

FIGURE 2. Comparison of colony silhouettes and variability. Scale bar valid for all sections. (A) Fertile Plumularia setacea from the intertidal region of Roscoff (Brittany, MHNG-INVE-79899). Note the small size of the plumes, likely due to the turbulent environment. (B) Plumularia setacea from a depth of at least 20 m collected in the Bay of Morlaix (Brittany, MHNG- INVE-36292). Note the large plumes, some of which are even branched. (C) Plumularia lagenifera, colony from Vancouver Island and identified by C. M. Fraser (BMHN1915.3.6.44). (D) Plumularia gaimardi, form on laminarians (MHNG-INVE- 34019). (E) Plumularia gaimardi, form with deep hydrothecae (SAM-H-1788).

FIGURE 3. Graphic illustration of measured values of the perisarc skeleton. (A) Single plume, ph = plume height. (B) Stem segments; cs = cauline segement length, cd = diameter of cauline segment in middle region, ah = origin of apophysis, al = apophysis length. (C) Repeated hydrocladial segments; as = length of ahydrothecate segment, hs = length of hydrothecate segment, td = depth of hydrotheca, nl = length of lateral nematotheca, tp = position of base of hydrotheca, np = position of infrathecal nematotheca.

FIGURE 12. Variability of microscopic structures of Plumularia gaimardi from South Africa. First row (A1–D1): stem segments and first hydrocladial segment. Second row (A2–D2): hydrothecate and ahydrothecate segments from the hydrocladia. Third row (A3–D3): abcauline walls of hydrothecae.

FIGURE 13. Variation of the gonothecae of Plumularia gaimardi, sex is indicated by symbols (♀ female, ♂ male).

FIGURE 14. Details of Plumularia gaimardi. (A) Hydrocladial segments in frontal view, note the narrowing upper part of the hydrotheca (SAM-H-1788). (B) Nematotheca lateral to hydrotheca in side view (SAM-H-0229). (C) Stolons with a nematotheca (SAM-H-2230B).