The true identity of Obama (Platyhelminthes: Geoplanidae) flatworm spreading across Europe
Author
Fernando Carbayo
Author
Marta Álvarez-Presas
Author
Hugh D. Jones
Author
Marta Riutort
text
Zoological Journal of the Linnean Society
2016
177
5
28
journal article
39194
10.1111/zoj.12358
8febfa05-2035-4a3e-90ce-e7df94b84cf5
269546
OBAMA NUNGARA
IS A NEW SPECIES
The new species shows morphological features of the genus and in our molecular trees it fits within a clade exclusively composed of species of
Obama
(
Obama
sp. 6 in
Carbayo
et al
., 2013
, and
Fig. 1
). Nevertheless, a diagnostic feature of the genus, multiple sensory pit rows opening at each side of the body, is absent in this species, as in
O. marmorata
. In this respect, the genus should be taxonomically revised.
The new species should be compared with species of
Pseudogeoplana
Ogren & Kawakatsu, 1990
and with other species of
Obama
.
The former genus includes species of
Geoplaninae
considered
species inquirendae
and
nomina dubia
because of insufficient morphological information, mainly internal. However, none of the species in
Pseudogeoplana
has a body colour pattern resembling the new species.
Among the 36 species of
Obama
, only
O. marmorata
compares well with the new species in having the dorsum patterned with marbled, short longitudinal dark striae. Furthermore, at first sight, the two species are very similar to each other in their general external appearance and in their internal features. To add complexity to the problem,
O. marmorata
and
O. nungara
sp. nov.
may be syntopic and at the time of sampling we suspected the slight differences in the colour pattern of the dorsum would be due to intraspecific variation. Nevertheless,
O. nungara
differs from
O. marmorata
in the following respects:
(1) the body is smaller (approximately 72% of the mean size of
O. marmorata
);
(2) the ground colour is not ‘light ivory’ (‘light brown with a pinkish tint’ in Froehlich’s specimens) but ‘golden yellow’ to ‘honey yellow’ and the dots are not green brown but black to ‘terra brown’, so giving it a darker general colour than
O. marmorata
;
(3) the eyes spread onto the dorsum in two lateral bands 1/3rd of the body width on each side, whereas in
O. marmorata
each band is 1/5th;
(4) the mouth and gonopore are relatively more anterior (median position 60 and 77%, respectively, from the anterior end) than in
O. marmorata
(72 and 86%), although there is overlap in the range of measurements;
(5) the length of the copulatory apparatus is 50– 75% of that of
O. marmorata
(this is significantly different from that of
O. marmorata
, ANOVA,
P
= 0.0000);
(6) the dorsal insertion of the penis is anterior to the level of the gonopore, not posterior as in
O. marmorata
, thus the base of the penis is narrower and more anterior than in
O. marmorata
;
(7) the glands producing pinkish (bluish is some stains) granules present in the stroma of the penis run in conspicuous bundles as they approach the subapical height of the penis to discharge their content in distinct patches, whereas in
O. marmorata
the penis glands run in discrete bundles discharging the secretion evenly through the penis epithelium;
(8) the muscle fibres in the stroma of the penis are more numerous and most of them are arranged in bundles, whereas in
O. marmorata
they are scarcer and packed in less apparent bundles;
(9) the male atrium possesses a kind of large sheathlike fold on the right side running from the ventral anterior side of the atrium to nearly the dorsal level to the gonopore, thus separating the male from the female atrium, whereas the male atrium of
O. marmorata
is not folded and not separat- ed from the female one;
(10) the very numerous glands discharging their cyanophilic granules into the male atrium pierce an annular-shaped surface of its lining epithelium, whereas in
O. marmorata
the surface pierced by this type of gland does not exist dorsally, thus resulting in a U-shaped surface.
Moreover, our molecular species delimitation analysis suggests strongly that
O. marmorata
and
O. nungara
are different species (
Fig. 2
; Supplementary material Fig. S1B). It also gives statistical support to the individuals of Brazil and the individuals from Europe and Argentina as belonging to the same species, although they are genetically quite differentiated. This is probably because the animals introduced to other countries originated from a different region of Brazil than the one analysed here.