Two new species of Haleciidae (Hydrozoa: Hydroida) from southern Australia

4 Pages·1993·1.1 MB·

by  Jeanette E Watson

TWO NEW SPECIES OF HALECIIDAE (HYDROZOA: HYDROIDA) FROM
SOUTHERN AUSTRALIA
Jeanette E. Watson
Honorary Associate, Museum of Victoria, 285 Russell Street, Melbourne, Victoria 3000
Watson, Jeanette E., 1993:03:31. Two new species of Haleciidae (Hydrozoa: Hydroida)
from southern Australia. Proceedings of the Royal Society of Victoria 105 (1): 81-84
ISSN 0035-9211.
Two new species of Haleciidae arc described from southern Australia. Halecium
amphibolum sp. nov. is a seagrass epiphyte and Campalecium alcoicum sp. nov. is cpizoic
on a crustose bryozoan. The latter species is the first record of Campalecium from
Australia.
TWO new species of hydroids referrable to the mal width 0.08-0.14 mm, distal width below
family Haleciidae were found during ecological hydrotheca 0.12-0.15 mm, secondary and later
studies in Port Phillip Bay, Victoria. One of the pedicels arising from geniculation just below
species, belonging to Halecium, occurs in the primary' hydrophore. Branching sympodia! to
epiphytic hydroid community of the seagrass roughly dichotomous, occurring below proximal
Amphibolis antarctica (Labill.) Sonder & hydrotheca on older stems.
Aschersen at QueensclifF, near Port Phillip Hydrotheca deep, not sessile, expanding to
Heads. The other species, belonging to Campa¬ margin. Margin at right angles to axis of pedicel,
lecium, is epizoic on a crustose bryozoan grow¬ strongly everted, with outrolled rim, width
ing on a jetty in shallow water. It is the first 0.18-0.23 mm, diaphragm distinct, width 0.11-
record of Campalecium from Australia. 0.13 mm, depth from margin to diaphragm
Type material lodged in the Museum of 0.05-0.08 mm, a few desmocytcs visible in
Victoria is denoted by the prefix NMV. empty hydrothecae. Up to three hydrothecal
replications common in older stems, replicated
Family Haleciidae Hincks, 1868 hydrothecae given off from diaphragm of pre¬
ceding one, pedicel short to absent. Hydranth
Halecium amphibolum sp. nov. large, robust, with about 20 tentacles.
Colonies dioecious. Gonothecae of both sexes
Fig. 1A-D similar in overall shape and size, irregularly
Etymology. The specific name refers to the host ovate, laterally flattened, length 0.7-0.9 mm,
plant. maximum width 0.5-0.8 mm, perisarc smooth,
borne on short, thick pedicel 0.10-0.15 mm
Type material. Holotypc NMV F59426, microslide,
long, arising below a hydrotheca on proximal
female colony from Amphibolis antarctica, 3 m,
Qucenscliff, Victoria, coll. J. E. Watson, 16 Nov. 1986. stem region or from hydrorhiza. Aperture of
Paratype NMV F59427, male colony (formalin pre¬ male gonotheca circular, 0.17-0.20 mm wide,
served) on Amphibolis antarctica, 3 m, Qucenscliff, with small upraised collar distally situated on
Victoria, coll. J. E. Watson. 24 Jun. 1986. one side of capsule, spermatogcnic mass con¬
tained within reticulated spadix. Aperture of
Description. Colonies consisting of up to six
mature female gonotheca an angular notch in
small, branched stems.
summit; gonophore containing up to eight large
Hydrorhiza tubular, thick and robust, 0.1 mm
ova.
in width, adherent to seagrass leaf. Stems short,
Perisarc of colonics honey-coloured, hydran-
unfascicled, up to 6 mm in height, taller stems
ths yellow', gonophores creamy-pink, aperture of
bearing several hydrothecae but many hydro¬
gonotheca dark brown.
thecae borne directly on hydrorhiza. Pcrisarc of
primary stem or pedicel thick, with at least three Remarks. In size of colony, Halecium amphibo¬
deep proximal annulations above junction with lum sp. nov. resembles some of the smaller
hydrorhiza, these continuing into distal region species of Haleciidae such as //. pusillum Sars,
but sometimes fading into smooth perisarc. Pri¬ 1857, Ii. nanum Alder, 1859 and H. corrugatis-
mary pedicel straight, 0.3-0.7 mm long, proxi¬ simum Trebilcock, 1928. However, careful
81
82 JEANETTE E. WATSON
Fig. 1. A-D, Halecium amphibolurn sp. nov. A, stem from holotype colony. B, female gonotheca with mature
gonophore. C, nearly mature male gonophorc. D, immature male gonophorc. E-H, Campalecium alcoicutn sp.
nov. E, hydrophorc with extended hydranth. F, gonotheca with nearly mature medusoid gonophorcs. G, micro-
basic mastigophorc from tentacles. H, oral microbasic mastigophore. Bar scales: A-D, 0.5 mm; E, 0.25 mm:
G, H, 10 mm. F not drawn to scale.
NEW SPECIES OF HALECIIDAE 83
examination of a large sample of fertile material gonotheca found on the colony was damaged
revealed no evidence of a degenerate hydranth before measurements could be made.
associated with the female gonophore such as Campalecium is best known from one widely
occurs in //. nanum; the gonothecae are lenticu¬ distributed species, C. medusiferum Torrcy,
lar in shape with smooth perisarc, unlike the 1902. The hydroid phase of C. medusiferum has
rugose gonothecae of 77 corrugatissimum\ and been recorded from the Mediterranean Sea, the
the aperture of the female gonotheca is a notch in Indo-West Pacific Ocean and the California
the perisarc, not tubular as in II. pusillum. coast, and the medusa has been recorded from
the Mediterranean Sea, the tropical Atlantic
Ecology. Halecium amphibolum sp. nov. is a sea-
Ocean and Malaysia.
grass obligate epiphyte (Watson 1992), found
Millard & Bouillon (1975) reported fertile col¬
only at the type locality of Queenscliff in south¬
onies (without liberated medusae) of Campale¬
eastern Australia. The colonies grow in the shel¬
cium cirratum (= Eucheilota cirrata Haeckel,
tered microhabitat of the axils of the seagrass
1879) from the Seychelles and included C.
leaves. They have a life-span of a few weeks from
medusiferum in its synonymy. Boero (1981),
settlement to senescence and are fertile in
however, doubted that these species are conspe-
spring.
cific because: (i) the newly liberated medusa of
C. medusiferum is different from that of C. cir-
Campalecium alcoicum sp. nov.
ratum; and (ii) the cnidomc of the Seychelles
Fig. 1E-F species differs from that of C. medusiferum, the
former containing microbasic mastigophores
Type material. Holotype NMV F51789, a colony (al¬
cohol preserved) on a bryozoan from wharf piles, 3 m, and “several other types of nematocyst in the
Point Henry, Port Phillip Bay, Victoria, coll. J. E. tentacles” (Millard & Bouillon 1975: 8) while
Watson, 11 Jan. 1992. the latter has both macrobasic and microbasic
mastigophores. He thus considered the Sey¬
Description. Colony stolonal, many hydrophores
chelles specimens probably to represent a new
arising from tubular hydrorhiza 0.04-0.06 mm
species.
in width. Hydrophores tubular, to 0.3-0.4 mm
Campalecium alcoicum is not closely related
high, of same diameter as hydrorhiza, distal end
to either C. medusiferum or C. cirratum?, the
expanded into shallow dish-shaped hydrotheca
differences being: (ij the larger hydrocaulus and
0.01 mm deep and 0.04-0.07 mm wide at mar¬
the several kinds of tentacular nematocysts in
gin. A ring of desmocytcs present.
the Seychelles species, compared with two kinds
Fully extended hydranth at least twice as high
both of smaller size in C. alcoicum; (ii) the oral
as hydrophore, column thin, thickening a little
macrobasic mastigophores of C. medusiferum
below origin of tentacles. Hypostome conical,
(see Boero 1981, fig. 5) were not found in A.
surrounded by single, amphicoronate whorl of
alcoicum; and (iii) the absence of an intertenta-
18-20 fine, filiform tentacles.
cular web from C. alcoicum.
Nematocysts small microbasic mastigo-
The finding of microbasic mastigophores in
phores, capsule 6-7 pm x 2pm, shaft about same
C. medusiferum would bring the apparent re¬
length as capsule, thread very long (to 500 pm),
lationship between this species and C. alcoicum
numerous on tentacles; a few larger microbasic
much closer. Examination of living material re¬
mastigophores around hypostome, capsule ba¬
vealed no trace of an intertacular web. If present,
nana- shaped, 20 x 4 pm, shaft very thick and
it is so reduced as to be vestigial. Since an inter-
ropy, about 35 pm long, thread a little thinner, at
tentacular web is diagnostic of Campalecium, its
least twice length of shaft.
absence from the Australian species suggests
Gonotheca arising from base of hydrophore
that the concept of the genus needs to be revised
and larger than it, top-shaped, widening distally
to accommodate varied development of this
to truncated summit, walls smooth, perisarc
structure.
thin, containing three medusa buds at different
stages of development.
Colonies transparent to white. Each medusa
bud with a yellow spot. REFERENCES
Remarks. The bryozoan substrate of Campale¬ Alder, J., 1859. Description of three new sertularian
zoophytes. Annals and Magazine of Natural
cium alcoicum sp. nov. was on the mussel
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Mytilus edulis planulatus (Lamarck) growing on
Boero, F., 1981. Systematics and ecology of the
wharf pilings in sheltered water. The single hydroid population of two Posidonia oceanica
84 JEANETTE E. WATSON
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