Conspectus cobitidum - Raffles Museum of Biodiversity Research

THE RAFFLES BULLETIN OF ZOOLOGY 2012
APPENDIX: NEW GENUS-GROUP AND FAMILY-GROUP NAMES
Ambastaia, new genus
Type species. — Botia nigrolineata Kottelat & Chu, 1987.
Diagnosis. — Ambastaia is distinguished from all other genera
of the family Botiidae by its unique colour pattern in
adults consisting in a whitish-yellowish background with a
black midlateral stripe on the flank and another, middorsal
stripe, with vertical bars connecting the two stripes and extending
on the lower half of the body. In A. nigrolineata only
the two stripes are present in juveniles and the bars appear at
about 40–50 mm SL. In A. sidthimunki, the mid-dorsal stripe
is often longitudinally divided by a whitish median area, or
a row of whitish blotches, and the midlateral stripe may appear
as a row of closely connected blotches; the juveniles
have not yet been described.
Etymology. — Named for Ambastai (or Ambastus in Latin),
a river in Ptolemy’s (ca. 90–168) Γεωγραφκ γφγησις
(Geographikê Hyphêgêsis, Geography). This river has been
identified as the Mekong (van der Meulen, 1974, 1975).
Gender feminine.
Remarks. — The colour pattern of A. nigrolineata and A.
sidthimunki and its ontogeny are unique within Botiidae. Both
were originally described in the genus Botia and they were
later transferred to Yasuhikotakia by Nalbant (2002). Still
the colour pattern distinguishes them from that of all species
of Yasuhikotakia, which includes a large blackish blotch at
the base of the caudal fin and, in juveniles, a number of narrow
bars on the flank (see figures in Kottelat, 2001b: 87). In
most individuals, these bars become indistinct with age. Other
elements of the colour pattern (e.g. middorsal stripes, black
spots and subdistal margin on fins) may be present. This
contrasts with Ambastaia in which the stripes appear first,
followed by the vertical elements. Those species of Yasuhikotakia
that have been studied osteologically have a long
process of the frontal along the anterior margin of the orbit
(called “spinous fringe” by Taki, 1972); it is missing in A.
sidthimunki. Based on this and other characters, Taki (1972:
78) commented that A. sidthimunki “appears to be the remotest
from [...] the rest in the group” [his modesta group,
equivalent to Yasuhikotakia]. This condition of the ‘spinous
fringe’ has not yet been checked in all known species and
therefore it is not used here as a diagnostic character.
The molecular phylogeny presented by Šlechtová et al. (2005)
included A. nigrolineata and A. sidthimunki and showed that
they are each other’s closest relative but not closely related
to the other species placed in Yasuhikotakia. On the contrary,
they form the sister-group of Sinibotia and together
they are the sister-group of Syncrossus. This lineage, in turn,
constitutes the sister group of Yasuhikotakia. This clearly
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shows that A. sidthimunki and A. nigrolineata form a distinct
lineage. With the recognition of Ambastaia, Yasuhikotakia
seems now monophyletic.
Admittedly, it is quite weak to diagnose a genus by its colour
pattern; combined with the molecular evidence it seems
however justified to formally recognise this lineage by a name
awaiting for (possible) more detailed anatomical studies.
Assuming that this kind of research will still get support and
be tolerated. I wish to point that to me, in botiids, the ontogeny
of the colour pattern seems much more informative than
the colour pattern itself. Unfortunately there is no published
information on the colour pattern of the juveniles of the
Chinese genera (Sinibotia, Leptobotia, Parabotia).
Theriodes, new genus
Type species. — Acanthophthalmus sandakanensis Inger &
Chin, 1962: 120.
Diagnosis. — Theriodes is distinguished from the other genera
of the family Cobitidae in Southeast Asia in having the
black marking at the base of the caudal-fin made of a single
small black spot; it is slightly vertically elongated, at midheight
of the caudal-fin base. The gill opening is small, oval,
its length is about equal to the length of the base of the pectoral
fin and it is located entirely above the base of the pectoral
fin. The anterior nostril is at the tip of a short conical
tube and the posterior nostril is not immediately adjacent to
the tube, but separated by a distance about equal to its own
diameter (shared with Kottelatlimia katik). The pectoral fin
has 5 branched rays. In the male the first two pectoral rays
are thickened and have a few tubercles along the anterior
edge; the second ray is branched but there is no membrane
between the branches and the posterior branch is much thinner
than the anterior one; superficially the ray may appear
unbranched (as originally described by Inger & Chin, 1962);
the branches are more discernible in females and juveniles.
The other pectoral rays are clearly branched, but the branching
point is close to the tip of the rays.
The following characters also help to distinguish the genus,
although none is unique to it: pelvic fin with 1 simple and 4
branched rays; dorsal-fin origin about halfway between pelvic-fin
origin and anal-fin origin; caudal fin rounded; lower
lip interrupted medially, each half with an inner, thickened
mental lobe; membrane connecting mental lobe to corner of
mouth with two barbel-like projections, one of them continuing
the mental lobe; barbels short, broad, somewhat triangular
and flattened; bifid suborbital spine; eye covered by
skin; 25–26 + 10–11 = 35–36 vertebrae (Kottelat & Lim,
1992: 202).