Morphological and molecular characterisation of Californian species ...

Studies on Metaporcelaimus
clusion in Metaporcelaimus rather than Aporcelaimellus.
Jana and Baqri (1981) described three females and one
male belonging to this species but having a larger general
size (body length 1.51-1.90 mm in females, 1.88 in
male) which exceeds the range of the type population
(body length 0.96-1.42 in females, no male) and raises
some doubts as to the identity of this material.
Metaporcelaimus conoidus comb. n.: A recent reexamination
of type material of this species (Álvarez-
Ortega & Peña-Santiago, 2010a) revealed that some of its
distinctive features (inner cuticle layer apparently bearing
a terminal discontinuity; slender body, a = 36-42; and
conical tail with rounded terminus, c ′ = 1.3) better fit the
pattern of Metaporcelaimus than that of Aporcelaimellus.
Metaporcelaimus cylindricus comb. n.: The true identity
of this taxon deserves further study, but the morphology
of its tail (conical, lacking a continuous and refractive
inner layer) supports its provisional transference to Metaporcelaimus.
Metaporcelaimus donghwaens comb. n.: The general
morphology of this species, especially that of the caudal
region, perfectly fits the new concept (conical tail, inner
cuticle layer bearing a distinct discontinuity, inner core
with a terminal digitation) of Metaporcelaimus and justifies
its transference to this genus.
Metaporcelaimus efficiens: The true identity of this
species remains obscure. Thorne & Swanger’s (1936)
original description is very poor in detail, but Andrássy
(2001) transferred it from Aporcelaimellus to Metaporcelaimus,
an action which is provisionally followed here.
Thorne & Swanger (1936) mentioned that Dorylaimus efficiens
was very similar to D. simplex, also originally described
by them, a species recently transferred from Metaporcelaimus
to Aporcella by Álvarez-Ortega et al. (2013).
On the other hand, M. efficiens is very similar, if not identical,
to M. raniensis (see below), from which it can be
distinguished by minor morphometric differences derived
from the study of only one female in each case.
Metaporcelaimus indicus comb. n.: Andrássy (2001)
regarded this species as a junior synonym of M. mombucae,
but there are several morphometric differences between
them, namely larger (L = 2.40-2.45 vs 1.83-2.34)
and more slender (a = 49-52 vs 28-42) body, more posterior
vulva (V = 57-58 vs 50-56), comparatively shorter
tail (c = 41-43 vs 30-36) and male unknown vs known.
On the other hand, assuming that the pars refringens vaginae
is absent, the general morphology of this species also
fits that of some members of Discolaiminae, although the
general size is larger. Hence, further studies are needed
to clarify its identity, although its conical tail and resemblance
to M. mombucae suggests it should be provisionally
classified under Metaporcelaimus rather than under
Aporcelaimellus.
Metaporcelaimus insignis comb. n.: A recent re-examination
of type material of this species (Álvarez-Ortega &
Peña-Santiago, 2011) revealed that some of its distinctive
features (slender body, a = 35-40; and conical tail with
finely rounded terminus, c ′ = 1.6-1.9) better fit the pattern
of Metaporcelaimus than that of Aporcelaimellus.
Metaporcelaimus littoralis comb. n.: Although the original
description of this species is not very detailed, the
morphology of the caudal region (conical with rounded
terminus, apparently with a terminal discontinuity of inner
cuticle layer, and short or notched inner core) seems
more similar to Metaporcelaimus than to Aporcelaimellus,
the reason why it is transferred to the former genus.
Metaporcelaimus parangalitzi comb. n.: Tail morphology
(conical with inner core forming a terminal digitation)
in this species fits well the Metaporcelaimus pattern.
Metaporcelaimus parmus comb. n., M. placus comb.
n. and M. thornei comb. n.: Álvarez-Ortega & Peña-
Santiago (2010a) have recently re-described or described
these species on the basis of type material. In all three
cases the tail is conical, with the inner cuticle layer weakly
refractive and discontinuous at the end, and the inner core
irregular and with terminal digitation.
Metaporcelaimus raniensis comb. n.: Altherr’s (1968)
original description of this species, based on only one
female, lacks many details and contains some inconsistencies,
for instance the morphometrics of the caudal region
significantly differ when data from text and those obtained
from illustrations are compared. Andrássy (2002b)
regarded it as a junior synonym of Aporcelaimellus taylori
Yeates, 1967, but there are some relevant differences between
both taxa: more slender body in M. raniensis (a =
44 vs 29), pars refringens vaginae present vs absent, and
more posterior vulva (V = 57 vs 50). It is herein regarded
as a valid species and, due to its conical tail with inner
core nearly reaching the terminus, provisionally classified
under Metaporcelaimus.
Metaporcelaimus shamimi comb. n.: Tail morphology
(conical with finely rounded tip with a terminal discontinuity
of inner cuticle layer) in this species fits well the
Metaporcelaimus pattern.
Metaporcelaimus silvanus comb. n.: The conical tail
with finely rounded tip of this species supports its inclusion
in Metaporcelaimus.
Vol. 00(0), 2012 21