Bibliographic Detail
Kraft, G.T., Conklin, K.Y. & Sherwood, A.R., 2014
Reference:
Kraft, G.T., Conklin, K.Y. & Sherwood, A.R. (2014). Tylotus laqueatus, a new species of Dicranemataceae (Gigartinales, Rhodophyta) from the Hawaiian Islands. Phycological Research 62: 16-28, 35 figs.
Abstract:
A rarely collected shallow-subtidal Hawaiian macroalga
has been determined anatomically and molecularly
to belong to an undescribed species of Tylotus J.
Agardh, the most widely distributed genus of the
small, mostly Australian-endemic family Dicranemataceae.
Thalli are repent and imbricate on calcareous
boulders at the type locality on Oahu, and are
anchored both basally and by haptera arising marginally
and ventrally on the (sub-)dichotomous, linear
axes. Simple or forked terete haptera can be a means
of perennation by the occasional direct issuing of
adventitious blades. Fronds are multiaxial and consist
of a broad pseudoparenchymatous medulla of thickwalled
cells surrounded on both sides by a two- or
three-layered small-celled pigmented cortex in which
numbers of glandular hairs are embedded. Tetrasporangia
are zonate, and gametophytes are monoecious.
Carpogonial branches are three-celled, directed to the
thallus surface, and borne laterally on inner-cortical
supporting cells; cystocarps are prominently protuberant
and scattered sparingly on dorsal frond surfaces,
the carposporophytes directed outwardly beneath an
ostiolate pericarp and connected to the parent gametophyte
across a broad placental base in which the
remnant auxiliary cell persists centrally. The inner
surface of the pericarp is unusual in producing extensive
patches or isolated islands of short gonimoblast
filaments with terminal carposporangia as an apparent
result of the implantation of gonimoblasts into the
tissue of the lining. Anatomy indicates that the new
species is more closely related to the East-Asian
Tylotus lichenoides Okamura than to the only other
described member of the genus, the type species
T. obtusatus (Sonder) J. Agardh from southern Australia.
An rbcL phylogeny supports placement of
sequences for Hawaiian specimens within the genus
Tylotus but distinct from all previously recorded
sequences of Tylotus. As is widely reported in other
molecular-phylogenetic analyses of the Gigartinales,
we find that support for generic and familial relationships
within the order is strong whereas that for
between-family relationships is low.