First reports of Grania (Clitellata: Enchytraeidae) from Africa and South America: molecular phylogeny and descriptions of nine new species
Author
Prantoni, Alessandro Lívio
Author
Wit, Pierre De
Author
Erséus, Christer
text
Zoological Journal of the Linnean Society
2016
2016-02-10
176
3
485
510
http://dx.doi.org/10.1111/zoj.12333
journal article
10.1111/zoj.12333
0024-4082
4720622
GRANIA
CF.
LEVIS
COATES & ERSÉUS, 1985
PROBABLY
GRANIA LEVIS
COATES & ERSÉUS, 1985: 111–112
,
FIG. 6
Material examined
USNM 1283176
, CE11570, whole-mounted, sexually immature specimen, with some segments amputated, from off
North Carolina
,
USA
,
33°10′23″N
,
76°45′23″W
. Continental shelf slope,
492 m
in depth, sand. Collected by
C. Erséus
,
20 May 2011
.
COI
barcode
KT428114
; for other genes, see
Table 1
.
Remarks
This barcoded, but immature specimen, and thus unsuitable for complete morphological description, was included in the phylogenetic analysis, to enlarge the taxonomic sampling from the north-western Atlantic region. Phylogenetically, this specimen came out as closely related to
G. carolinensis
sp. nov.
(
Fig. 15
), but it is morphologically distinct by its complete lack of chaetae. The latter trait suggests that this specimen could belong to
Grania levis
Coates & Erséus, 1985
, originally described from somewhat further north, from Georges Bank, south-east of
Massachusetts
,
USA
.
GENETIC ANALYSES
COI clustering
The Bayesian inference of the
COI
sequences divide the 38 individuals into ten well-supported clades (
Fig. 11
), four of which are found in
South Africa
, two in
Chile
, one in
Brazil
, and three in the North Atlantic. Within-clade variation is generally low, but in one clade, i.e. all specimens referred to the new taxon
G. chilensis
sp. nov.
, there is a notable subclustering pattern, dividing this clade into four subclades. A haplotype network (
Fig. 12
) indicates that
G. chilensis
sp. nov.
is structured geographically, with two subclades found in the southernmost site (Valdivia), one subclade in the northernmost site (Coquimbo), and an intermediate subclade in the intermediately located site (Concepcion). Pairwise genetic distances indicate that in general there is a strong barcoding gap present between lineages within this group. In the
G. chilensis
sp. nov.
clade, however, there is higher than average within-species divergence, although not nearly as great as the lowest between-species differences (
Fig. 13
).
ITS clustering
The Bayesian inference analysis of 23
ITS
sequences supports all ten clusters found in the mitochondrial data (
Fig. 14
); however, although there is also variation within the
G. chilensis
sp. nov.
cluster in the
ITS
region, the geographic substructuring is not seen here. Instead, the variation seems to be randomly distributed with respect to geography.
Phylogenetic placement of new species
The updated phylogeny is completely congruent with that described in
De Wit
et al
. (2011b)
, containing three main clades (A, B, C in
Fig. 15
). All of the South African species form one strongly supported clade within clade A, together with all the North Atlantic species. By contrast, the Chilean and the Brazilian species are placed in clade B, together with
Grania curta
De Wit & Erséus, 2007
and
G. americana
.
Grania unitheca
sp. nov.
from shallow water in
North Carolina
(North Atlantic) is placed together with the other North American species
G. monospermatheca
(its sister taxon) and
G. laxartus
; however,
G. carolinensis
sp. nov.
and the closely related immature specimen of
Grania
cf.
levis
, both found in deep water off the North Carolinian coast, are placed as the sister clade of
G. postclitellochaeta
and the cryptic
G. occulta
, whereas
G. ovitheca
, which is morphologically identical to
G. occulta
, is strongly supported as the sister to this four-taxon group (
Fig. 15
).