Marine Macrodasyida (Gastrotricha) from Hokkaido, Northern Japan
Author
Yamauchi, Shohei
Department of Natural History Sciences, Graduate School of Science, Hokkaido University, Sapporo, Hokkaido 060 - 0810, Japan
Author
Kajihara, Hiroshi
Faculty of Science, Hokkaido University, Sapporo, Hokkaido 060 - 0810, Japan E-mail: kajihara @ eis. hokudai. ac. jp (HK) & Corresponding author
kajihara@eis.hokudai.ac.jp
text
Species Diversity
2018
2018-11-25
23
183
192
journal article
10.12782/specdiv.23.183
2189-7301
5738233
3FA0A429-1676-4326-B8D3-FFBA8FE403C9
Turbanella lobata
sp. nov.
(
Figs 7
,
8
)
Material examined.
Holotype
,
ICHUM 4982
(adult),
Ishikari
beach,
Hokkaido
,
Japan
(
43°15.420′N
,
141°21.438′E
), medium-grained sand,
58 cm
depth,
5 m
landward from high-water level,
14 May 2014
.
Paratype
:
ICHUM
4983 (subadult), same collection data as for
holotype
.
Etymology.
The specific name is an adjective from the Latin
lobatus
(lobed), referring to the lateral lobes at U11.
Description.
Habitus.
Adult Lt 390 µm; L of anterior end to PhJIn (at U30) 132 µm. Body short; head slightly sculpted, with lateral cones at U07 and additional lateral lobes at U11 (
Figs 7A
,
8A
); neck constriction at U11; trunk widest in mid-body region, tapering gradually to caudal base; caudum moderately cleft, incised from its tips to U97, medial cone absent. Glands 35–40 per side, medium in size (6 µm in diameter), scattered in lateral and medial columns.
Adhesive tubes.
TbA four per side (L 5–7 µm), occurring on lobe inserted at U11 (
Fig. 7B
); TbL 10–12 per side (L 8–12 µm), some bearing cilia, irregularly spaced and often asymmetrically arranged, with tow in pharyngeal region, one behind anal opening, and others along intestine; TbD 7–8 per side, with one in pharyngeal region and remainder along intestine; ‘cirrata’ [Seitenfüsschen] tubes occurring at U38; TbP four per side, arrayed along rear edge of each lobe, lengthening medial to lateral (L 3–9 µm) (
Figs 7A, B
,
8C
).
Ciliation.
Mouth surrounded by short sensory cilia (L 3 µm), with longer cilia (L 5 µm) inserted at points of head sculpting on each side; ciliary hairs (L 11 µm) forming cir- cum-cephalic band at U07; sensory cilia (L 9 µm) occurring on trunk in lateral columns; each Tb inserted on trunk, bearing cilium (L 11 µm) arising from rear apex of tube support; ventral locomotory cilia (L 12 µm) running in two longitudinal bands along lateral body margins to anus (
Fig. 7B
)
Fig. 6.
Turbanella cuspidata
sp. nov.
A, SEM image of head and neck region; arrowhead indicates projective organ, left anteroventral view, paratype ICHUM 4991. B–D, Differential interference contrast photomicrographs of holotype (ICHUM 4980); B, head and neck region, ventral view; C, mid-body region showing oocytes; D, caudal part, ventral view, showing medial caudal cone and arrangement of posterior adhesive tubes (TbP). Abbreviation: TbA, anterior adhesive tube.
Digestive tract.
Mouth terminal, of medium width (11 µm); buccal cavity conical-shaped; walls lightly cuticular; pharynx of medium width throughout, with basal pharyngeal pores at U30; intestine narrowing anterior to posterior; anus at U91.
Reproductive tract.
Hermaphroditic; paired testes extending posteriorly from U59, their vasa deferentia recurving anteriorly, but terminal not seen; bilateral oocytes developing posterior to anterior, largest (53×23 µm) in anterior region of intestine (
Figs 7A
,
8B
).
Remarks.
Among approximately 30 species in the genus
Turbanella
, five species share many features with
Turbanella lobata
sp. nov.
:
T. caledoniensis
Hummon, 2008
;
T. lutheri
Remane, 1952
;
T. otti
Schrom, 1972
;
T. pacifica
Schmidt, 1974
; and
T. subterranea
Remane, 1934
. These species differ from
T. lobata
sp. nov.
as follows:
T. caledoniensis
lacks lateral head lobes and the neck constriction;
T. lutheri banelloides
was originally established in
Paradasys
(
Boaden 1960
)
, suggesting that transfer of the species to
Cephalodasys
(
Hummon 1974
)
may require a revision. Our analysis indicates
Cephalodasys
and
Cephalodasyidae
as currently diagnosed (
Hummon and Todaro 2010
; Kieneke
et al.
2015) are not monophyletic (
Fig. 4
). However, additional gene markers may recover them as monophyletic, because support values for basal nodes are generally low (
Fig. 4
). In any case, inclusion of
C. maximus
Remane, 1926
, the
type
species of
Cephalodasys
, as well as
P. subterraneu
, the
type
species of
Paradasys
(see Remarks for
C. mahoae
sp. nov.
above), in molecular phylogenetic context is indispensable to test the appropriateness of the generic placement of
C. mahoae
sp. nov.
, as well as for taxonomic revision of the family.