Taxonomic review of Thoracostomopsidae (Nematoda, Enoplida): state of the art, list of valid species and dichotomous keys
Author
De Souza, João V.
0009-0009-4985-086X
https: // orcid. org / 0009 - 0009 - 4985 - 086 X
Author
Maria, Tatiana F.
0000-0002-7553-2031
https: // orcid. org / 0000 - 0002 - 7553 - 2031
text
Zootaxa
2023
2023-11-03
5361
4
463
496
https://www.mapress.com/zt/article/download/zootaxa.5361.4.2/52207
journal article
10.11646/zootaxa.5361.4.2
1175-5326
10152589
DAB237DC-1444-4007-BCCA-CB92CBE66617
Genus
Mesacanthion
(
Filipjev, 1927
)
De Coninck and Schuurmans Stekhoven, 1933
The genus
Mesacanthion
was first erected as a subgenus of
Enoplolaimus
by
Filipjev (1927)
with the original description of seven species:
Mesacanthion banale
(
Filipjev, 1927
) De Conninck & Schurmans Stekhoven, 1933
,
Mesacanthion breviseta
(
Filipjev, 1927
) De Conninck & Schurmans Stekhoven, 1933
,
Mesacanthion ditlevseni
(
Filipjev, 1927
) De Conninck & Schurmans Stekhoven, 1933
,
Mesacanthion karense
(
Filipjev, 1927
) De Conninck & Schurmans Stekhoven, 1933
,
Mesacanthion lucifer
(
Filipjev, 1927
) De Conninck & Schurmans Stekhoven, 1933
,
Mesacanthion majus
(
Filipjev, 1927
) De Conninck & Schurmans Stekhoven, 1933
,
Mesacanthion klugei
(
Filipjev, 1927
) De Conninck & Schurmans Stekhoven, 1933
and the inclusion of three other species
Mesacanthion diplechma
(
Southern, 1914
)
Filipjev, 1927
,
M. audax
and
Mesacanthion conicum
(
Filipjev, 1918
)
Filipjev, 1927
, which were previously described as
Enoplus
and
Enoplolaimus
(in the case of the last two species).
De Coninck and Schuurmans Stekhoven (1933)
raised
Mesacanthion
to genus including all species described by
Filipjev (1927)
and transfered other six species to it:
M. infantile
;
Mesacanthion latignathum
(
Ditlevsen, 1918
)
De Coninck and Schuurmans Stekhoven, 1933
;
Mesacanthion microsetosum
(
Allgén, 1932
)
De Coninck and Schuurmans Stekhoven, 1933
;
Mesacanthion oxycephalum
(
Ditlevsen, 1926
)
De Coninck and Schuurmans Stekhoven, 1933
;
Mesacanthion tenuicaudatum
(
Ssaweljev, 1912
)
De Coninck and Schuurmans Stekhoven, 1933
and
Mesacanthion virile
(
Ditlevsen, 1930
)
De Coninck and Schuurmans Stekhoven, 1933
. Two decades later,
Mesacanthion hirsutum
Gerlach, 1953
was described based on a male and a female from
Italy
.At the same time, a genus review was proposed by
Wieser (1953)
who considered all species described by Allgén as doubtful, including
Mesacanthion primitivum
Allgén, 1929
,
Mesacanthion gracilisetosum
Allgén, 1930
,
Mesacanthion paradentatum
Allgén, 1932
,
Mesacanthion donsitarvae
Allgén, 1935
,
M. pacificum
and
M. hawaiiense
; and transfered
M. latignathum
to
Mesacanthoides
and
M. klugei
and
M. oxycephalum
to
Paramesacanthion
.
This author also described two other species
Mesacanthion ungulatum
Wieser, 1953
and
Mesacanthion longissimesetosum
Wieser, 1953
and proposed an identification key for eight of the 14 valid species known at the time. Later, 33 species were considered as valid and six as invalid by
Gerlach & Riemann (1974)
who also corrected the species epithet to comply with the rules of Latin grammar. Later, eight species were described, and
Jeong
et al.
(2019)
did a detailed review of the genus presenting 38 valid species and suggesting two species (
Mesacanthion brachycolle
Allgén, 1959
and
Mesacanthion ungulatum
Wieser, 1953
) as
species inquirendae
and nominated one as
nomen
nudum
(
M. microsetosum
– here we consider this species as
species inquirenda
within
Paramesacanthion
). These authors also provided a taxonomic key for 22 species with spicules shorter than 2 anal body diameters (abd). The most recent species added to this genus are
M. bifidum
,
Mesacanthion longigubernaculum
Lo Russo & Pastor de Ward, 2021
and
Mesacanthion sanantoniensis
Lo Russo & Pastor de Ward, 2021
, all occurring along
the Argentine
coast. Here, we consider
Mesacanthion arcuatile
Wieser, 1959
,
M. banale
,
M. conicum
and
Mesacanthion cricetoides
Wieser, 1959
as
species inquirendae
because these species present only female descriptions. We also consider
M. karense
as
species inquirenda
since it is based on juvenile description, and
M. tenuicaudatum
because its illustrations are missing in the original description. The given key includes all 36 valid species and it is partially adapted from the one provided by
Jeong
et al.
(2019)
which presents only species with spicules smaller than 2 abd.
Diagnosis
based in
Wieser (1953)
;
Platt &
Warwick
(1983)
;
Smol
et al.
2014
and
Jeong
et al.
(2019)
: Outer labial and cephalic setae situated at middle or anterior end of cephalic capsule. Mandible well-developed, provided with claws, arch-shaped, consisting of two rod-like columns anteriorly united by a curved bar. Teeth shorter than mandibles. Spicule mostly short, unipartite and symmetrical, sometimes long, bipartite (divided by a seam:
M. ditlevseni
) and asymmetrical (anisomorphic and anisometric:
M. diplechma
). If long, usually gubernaculum present with caudal apophysis. Marine and freshwater.
Number of valid species:
36
1.
Mesacanthion africanthiforme
Warwick
, 1970a
(English Channel)
2.
Mesacanthion africanum
Gerlach, 1957b
(Central Africa)
3.
Mesacanthion agubernatus
Vitiello, 1971
(Mediterranean)
4.
Mesacanthion alexandrinus
Nicholas, 1993
(
Lake Alexandrina
,
South Australia
)
5.
Mesacanthion arabium
Warwick
, 1973 (Arabian Sea)
6.
Mesacanthion armatum
Timm, 1961
(Bay of Bengal,
lapsus armatus
)
7.
Mesacanthion audax
(
Ditlevsen, 1918
)
Filipjev, 1927
(Öresund)
Syn.
Enoplolaimus audax
Ditlevsen, 1918
8.
Mesacanthion bifidum
Lo Russo & Pastor de Ward, 2021
(Nuevo Gulf,
Argentina
)
9.
Mesacanthion breviseta
(
Filipjev, 1927
)
De Coninck & Schuurmans Stekhoven, 1933
(Barents Sea)
Syn.
Enoplolaimus (Mesacanthion) breviseta
Filipjev, 1927
10.
Mesacanthion cavei
Inglis, 1964
(
South Africa
)
11.
Mesacanthion ceeum
Inglis, 1964
(
South Africa
)
12.
Mesacanthion diplechma
(
Southern, 1914
)
Filipjev, 1927
(Irish
Coast
of Atlantic)
Syn.
Enoplus diplechma
Southern, 1914
13.
Mesacanthion ditlevseni
(
Filipjev, 1927
)
De Coninck & Schuurmans Stekhoven, 1933
(Barents Sea)
Syn.
Enoplolaimus (Mesacanthion) ditlevseni
Filipjev, 1927
Enoplolaimus angustignathus
Ditlevsen, 1928
14.
Mesacanthion fricum
Inglis, 1966
(
South Africa
,
lapsus frica
)
15.
Mesacanthion heterospiculum
Sergeeva, 1974
(Black Sea,
Russia
)
16.
Mesacanthion hirsutum
Gerlach, 1953
(Mediterranean)
17.
Mesacanthion infantile
(
Ditlevsen, 1930
)
De Coninck & Schuurmans Stekhoven, 1933
(
New Zealand
)
Syn.
Enoplolaimus infantilis
Ditlevsen, 1930
Enoplolaimus mortenseni
Allgén, 1951
Enoplolaimus philippinensis
Allgén, 1951
18.
Mesacanthion jejuensis
Jeong, Tchesunov & Lee, 2019
(
Jeju
Island,
South Korea
)
19.
Mesacanthion kerguelense
Mawson, 1958
(Kerguelen Islands)
20.
Mesacanthion longigubernaculum
Lo Russo & Pastor de Ward, 2021
(
Chubut
, San Jorge Gulf,
Argentina
)
21.
Mesacanthion longispiculum
Gerlach, 1954b
(Mediterranean)
22.
Mesacanthion longissimesetosum
Wieser, 1953
(
Chile
,
lapsus longissimesetosus
)
23.
Mesacanthion lucifer
(
Filipjev, 1927
)
De Coninck & Schuurmans Stekhoven, 1933
(Barents Sea)—
type
species
Syn.
Enoplolaimus (Mesacanthion) lucifer
Filipjev, 1927
24.
Mesacanthion majus
(
Filipjev, 1927
)
De Coninck & Schuurmans Stekhoven, 1933
(Kara Sea,
lapsus
major
)
Syn.
Enoplolaimus (Mesacanthion) major
Filipjev, 1927
25.
Mesacanthion marisalbi
Galtsova, 1976
(White Sea)
26.
Mesacanthion monhystera
Gerlach, 1967
(Red Sea)
27.
Mesacanthion obscurum
Gagarin & Klerman, 2006
(Mediterranean Sea, Israeli
Coast
)
28.
Mesacanthion pali
Wieser, 1959
(Puget Sound,
Washington
,
USA
)
29.
Mesacanthion pannosum
Wieser, 1959
(Puget Sound,
Washington
,
USA
)
30.
Mesacanthion propinquum
Gagarin & Klerman, 2006
(Mediterranean Sea, Israeli
Coast
)
31.
Mesacanthion proximum
Gerlach, 1957a
(Santos,
Brazil
)
32.
Mesacanthion rigens
Gerlach, 1957a
(Bertioga,
Brazil
)
33.
Mesacanthion sanantoniensis
Lo Russo & Pastor de Ward, 2021
(
Rio Negro
, San Matías Gulf,
Argentina
)
34.
Mesacanthion southerni
Warwick
, 1973 (Arabian Sea)
35.
Mesacanthion studiosum
Inglis, 1964
(
South Africa
,
lapsus studiosa
)
36.
Mesacanthion virile
(
Ditlevsen, 1930
)
De Coninck & Schuurmans Stekhoven, 1933
(Stewarti Island,
New Zealand
)
Syn.
Enoplolaimus virilis
Ditlevsen, 1930
SPECIES INQUIRENDAE
1.
Mesacanthion arcuatile
Wieser, 1959
(Alki Beach,
Washington
,
USA
,
lapsus arcuatilis
)
2.
Mesacanthion banale
(
Filipjev, 1927
)
De Coninck & Schuurmans Stekhoven, 1933
(Barents Sea)
Syn.
Enoplolaimus (Mesacanthion) banalis
Filipjev, 1927
3.
Mesacanthion brachycolle
Allgén, 1959
(
Falkland Islands
)
4.
Mesacanthion conicum
(
Filipjev, 1918
)
Filipjev, 1927
(Black Sea,
Russia
)
Syn.
Enoplolaimus conicus
Filipjev, 1918
5.
Mesacanthion cricetoides
Wieser, 1959
(Richmond Beach,
Washington
,
USA
)
6.
Mesacanthion donsitarvae
(
Allgén, 1935
)
Wieser, 1953
(
Norway
)
Syn.
Enoplolaimus donsitarvae
Allgén, 1935
7.
Mesacanthion gracilisetosum
(
Allgén, 1930
)
Wieser, 1953
(
Macquarie Island
)
Syn.
Enoplolaimus gracilisetosus
Allgén, 1930
8.
Mesacanthion hawaiiense
(
Allgén, 1951
)
Wieser, 1953
(Honolulu,
Hawaii
)
Syn.
Enoplolaimus hawaiiensis
Allgén, 1951
9.
Mesacanthion karense
(
Filipjev, 1927
)
De Coninck & Schuurmans Stekhoven, 1933
(Kara Sea)
Syn.
Enoplolaimus (Mesacanthion) karensis
Filipjev, 1927
10.
Mesacanthion pacificum
(
Allgén, 1947
)
Wieser, 1953
(Gulf of
Panama
, Perlas Island)
Syn.
Enoplolaimus pacificus
Allgén, 1947
11.
Mesacanthion paradentatum
(
Allgén, 1932
)
Wieser, 1953
(Campbell Island,
lapsus
paradentatus
)
Syn.
Enoplolaimus paradentatus
Allgén, 1932
12.
Mesacanthion primitivum
(
Allgén, 1929
)
Wieser, 1953
(Skagerrak,
lapsus
primitivus
)
Syn.
Enoplolaimus primitivus
Allgén, 1929
13.
Mesacanthion tenuicaudatum
(
Ssaweljev, 1912
)
De Coninck & Schuurmans Stekhoven, 1933
(White Sea)
Syn.
Enoplolaimus tenuicaudatus
Ssaweljev, 1912
14.
Mesacanthion ungulatum
Wieser, 1953
(Seno Reloncavi,
Chile
,
lapsus ungulatus
)