Ceriantharia (Cnidaria) from Australia, New Zealand and Antarctica with Descriptions of Four New Species
Author
Stampar, Sérgio N.
Laboratório de Evolução e Diversidade Aquática-LEDA, Departamento de Ciências Biológicas, Universidade Estadual Paulista (UNESP), FCL / Assis, Av. Dom Antônio, 2100, 19806 - 900, Assis, SP, Brazil
Author
Mills, V. Sadie
NIWA Invertebrate Collection, National Institute of Water and Atmospheric Research, 301 Evans Bay Parade Hataitai, 6021 Wellington, New Zealand
Author
Keable, Stephen J.
Australian Museum Research Institute, Australian Museum, 1 William Street, Sydney NSW 2010, Australia
text
Records of the Australian Museum
2020
2020-07-29
72
3
81
100
journal article
10.3853/j.2201-4349.72.2020.1762
2201-4349
4654407
62E3C79A-499F-48DE-AFD9-111D52235D33
Pachycerianthus delwynae
Carter, 1995
Fig. 1
A–D
Pachycerianthus delwynae
Carter, 1995: 2–3
; figs 1b, 2.
Pachycerianthus longistriatus
Carter, 1995: 3–4
, junior
synonym.
Specimens examined
. Australian Museum (AM)—
Australia
, Sydney—G15399 (
holotype
of
P. delwynae
) Port Jackson, Chowder Bay,
33°50'30"S
151°15'12"E
(
15/ ix/1989
), depth
15 m
;
G15404
Port Jackson
,
Manly Pool
,
33°50'S
151°17'E
(1957)
;
G14526,
Port Jackson
,
Camp Cove
,
33°50'S
151°16'E
(
2 specimens
)
;
G15808
Port Jackson
,
Vaucluse Bay
,
33°51'S
151°16'E
(many specimens)
;
G15400 (
paratype
of
P. delwynae
)
Port Jackson
,
Bottle
and
Glass Rocks
,
33°50'54"S
151°16'12"E
(
13/vii/1989
), depth
5 m
;
G15401 (
paratype
of
P. delwynae
)
Port Jackson
,
Bottle
and
Glass Rocks
,
33°50'54"S
151°16'12"E
(
20/vii/1989
), depth
7 m
;
G12555 (
paratype
of
P. longistriatus
)
Port Jackson
;
G15403 (
paratype
of
P. longistriatus
)
Port Jackson
,
Chowder Bay
,
33°50'S
151°17'E
;
G12554 (
paratypes
of
P. longistriatus
)
Port Jackson
(09/1886) (
5 specimens
in jar but only
3 in
good condition and only 3 cited by
Carter (1995))
;
G15406 (
paratypes
of
P. longistriatus
)
Port Jackson
,
Off Dawes Point
,
33°50'S
151°12'E
(
2 specimens
)
;
G12553 (
paratype
of
P. longistriatus
)
Port Jackson
;
G13558 (
paratype
of
P. longistriatus
)
Port Jackson
;
G13561 (
paratype
of
P. longistriatus
)
Port Jackson
,
G15405 (
paratype
of
P. longistriatus
)
Port Jackson
,
Drummoyne
(
viii/1963
)
;
G15402 (
holotype
of
P. longistriatus
)
Port Jackson
,
Taylors Bay
,
33°50'S
151°17'E
(
20/vii/1989
), depth
5 m
.
Remarks
. Closely related sympatric species always arouse much curiosity, especially regarding how the processes of speciation have occurred. However, the occurrence of two species of
Pachycerianthus
described from Sydney (Port Jackson) by
Carter (1995)
are not supported.
Carter (1995)
notes that separation of the two species based on anatomy is difficult because the differences in mesenterial organization are slight, but the external morphology, especially tentacle colouration, is more consistent with banded marginal tentacles in
P. delwynae
and with distinctive longitudinal stripes on the marginals in
P. longistriatus
.
However, colour patterns have been shown to be highly variable in Cnidaria, especially in
Ceriantharia
, where numerous examples of different colour morphs have been found to represent a single species when other characters are considered (e.g.,
Molodtsova
et al.
, 2011
;
Stampar
et al.
, 2012
(including molecular data);
Stampar
et al.
, 2015
). Some species have different colour morphs depending on the reproduction season that each polyp was produced (Stampar
et al.
, submitted), consequently, colour is not a reliable taxonomic character in
Ceriantharia
. Leaving aside tentacle colouration patterns, the two main anatomical features listed by
Carter (1995)
that differentiate the species are not consistent, presenting variations that overlap. The first of these is the arrangement of mesenteries.
Carter (1995)
indicates that in
P. delwynae
the M2 mesentery is longer than the M1 and indicates an opposite pattern in
P. longistriatus
, in which mesentery M2 is shorter than M1. Observing the same specimens studied by
Carter (1995)
it is possible to verify this pattern is only present in some individuals, in other specimens this pattern does not exist or is not as evident as described. However, two specimens (AM G12554 and AM G15405, both nominally
paratypes
of
P. longistriatus
) display a mixture of both morphological patterns; one side (from siphonoglyph to multiplication chamber) has mesenteries with the M2 longer than the M1, the other side has the inverse mesentery M1 is longer than the M2. The other character used to justify the separation into two species is the distribution of the insertion of the tentacles. This character is much more inconsistent than the form of the mesentery, at least four different arrangements occur. However, the most important aspect is that there is no difference in the number of pseudocycles of the tentacles of each type (marginal or labial) in all specimens. Therefore, it is not possible to keep these specimens as two separate species,
Pachycerianthus delwynae
is retained instead of
P. longistriatus
based on page precedence in
Carter (1995)
.