Variation of Number of Pores on the Carapaces of Group A Species of the Genus Loxoconcha (Crustacea, Ostracoda) Following the Molting
Phylogeny of all extant twenty-eight species of Group A of the genus Loxoconcha are examined in this study. Basing on the total number of pores on carapaces, three species subgroups of this genus are shown by Differentiation of Distributional pattern of Pore-system (DDP) analysis. All species posses...
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Zoodiversity| _version_ | 1874092725343617024 |
|---|---|
| author | Le, D. D. |
| author_facet | Le, D. D. |
| author_institution_txt_mv | [
{
"author": "D. D. Le",
"institution": "Ho Chi Minh City University of Industry and Trade (HUIT), Ho Chi Minh City, Vietnam",
"orcid": ""
}
] |
| author_sort | Le, D. D. |
| baseUrl_str | https://ojs.akademperiodyka.org.ua/index.php/Zoodiversity/oai |
| collection | OJS |
| container_end_page | |
| container_issue | 1 |
| container_start_page | |
| container_title | Zoodiversity (Vestnik Zoologii) |
| container_volume | 58 |
| datestamp_date | 2026-08-20T12:37:09Z |
| description | Phylogeny of all extant twenty-eight species of Group A of the genus Loxoconcha are examined in this study. Basing on the total number of pores on carapaces, three species subgroups of this genus are shown by Differentiation of Distributional pattern of Pore-system (DDP) analysis. All species possess identical number and same distributional pattern of pore-system in and before A-4 instar. The difference in the total number of pores on carapaces is found from the instar A-3 to adult and thus three patterns are recognized. In the instar A-3, these numbers of subgroup A1, A2 and A3 are 42, 43 and 44, respectively. Additionally, the present study shows an identical number of anterior false radial pores among the subgroups at all instars. However, the number of posterior false radial pores is different among three subgroups from A-3 instar. In this instar, these numbers of subgroup A1, A2 and A3 are equivalent to 3, 4 and 5. By combination of this study and previous studies, geographical distribution of three subgroups is shown. Species of subgroup A1 distribute worldwide except the distributional areas of subgroups A2 and A3. While, species of subgroup A2 and A3 only reside in Atlantic coasts of Europe, northern Africa and coasts of the Mediterranean Sea. |
| doi_str_mv | 10.15407/zoo2024.01.069 |
| first_indexed | 2025-07-17T12:36:46Z |
| format | Article |
| fulltext |
© Publisher Publishing House "Akademperiodyka" of the NAS of Ukraine, 2024. The article is published under
an open access license CC BY-NC-ND (https://creativecommons.org/licenses/by-nc-nd/4.0/)
UDC 595.33
VARIATION OF NUMBER OF PORES ON THE CARAPACES OF
GROUP A SPECIES OF THE GENUS LOXOCONCHA (CRUSTACEA,
OSTRACODA) FOLLOWING THE MOLTING
D. D. Le
Ho Chi Minh City University of Industry and Trade (HUIT),
140 Le Trong Tan St.,
Tan Phu Dist., Ho Chi Minh City, Vietnam
E-mail: dungld@hufi.edu.vn
Doan Dung Le (https://orcid.org/0000-0002-9519-8878)
urn:lsid:zoobank.org:pub:EF3FB9C8-645D-4EC0-AB9F-14A9DBAA203E
Variation of Number of Pores on the Carapaces of Group A Species of the Genus Loxoconcha
(Crustacea, Ostracoda) Following the Molting. Le, D. D. — This study examines the phylogeny of all
twenty-eight recent species of Group A of the genus Loxoconcha Sars, 1866. Based on the total number of
pores on the carapace, three species subgroups of this genus are shown by Differentiation of Distributional
pattern of Pore-system (DDP) analysis. All species have the same number and distribution pattern of
pores in and before A-4 instar. The difference in the total number of pores on the carapace is found from
instar A-3 to adult, and thus three patterns are recognised. In instar A-3 these numbers are 42, 43 and
44 for subgroups A1, A2 and A3 respectively. In addition, the present study shows an identical number
of anterior false radial pores among the subgroups at all instars. However, the number of posterior false
radial pores is different in three subgroups from instar A-3. In this instar, these numbers of subgroups A1,
A2 and A3 are equivalent to 3, 4 and 5. By combining this study with previous studies, the geographical
distribution of the three subgroups is shown. Species of subgroup A1 are distributed worldwide, except
for the distribution areas of subgroups A2 and A3. Species in subgroups A2 and A3 are restricted to the
Atlantic coasts of Europe, North Africa and the Mediterranean.
Key words : Crustacea, Ostracoda, Loxoconcha, classification, phylogeny, morphology.
Introduction
The genus Loxoconcha Sars, 1866 is one of the most diverse recent ostracod taxa. A total of 575 species of
the genus Loxoconcha have been identified around the World (Brandão et al., 2015). The species of this genus
are distributed in low to middle latitude areas in marine and brackish waters. In Japan, the species of this genus
are widespread from south to north (Nakao & Tsukagoshi, 2002; Tanaka & Ikeya, 2002; Sato & Kamiya, 2007;
Le & Tsukagoshi, 2014).
Zoodiversity, 58(1): 69–78, 2024
DOI 10.15407/zoo2024.01.69
Morphology
70 D. D. Le
As for the phylogenetic view of the genus Loxoconcha, there are several remarkable papers. Kamiya (1988)
described two main life history modes in Loxoconcha species, i. e., phytal and bottom-dwelling, and suggested
that these modes reflect differences in adaptations for each microhabitat. The clear difference in carapace
morphology between species of the two life modes was demonstrated. The phytal species were circular in lateral
view and rugby ball shaped in posterior view, whereas the bottom-dwelling species were elongated rectangular
in lateral view and triangular in posterior view. Kamiya (1989) interpreted the different distribution patterns of
pore systems in adults of the phytal species L. japonica Ishizaki, 1968 and the benthic species L. uranouchiensis
Ishizaki, 1968, especially in the ventral region, as a result of adaptation to their respective microhabitats. Based on
carapace morphology, Tanaka & Ikeya (2002) divided the East Asian genus Loxoconcha into five species groups.
The migration and speciation patterns of four species of the L. japonica group were presented. Ishii et al. (2005)
studied 17 species of Loxoconcha around Japan and concluded that they can be divided into two groups according
to the Pore Pattern below Eye tubercle (PPE) analysis. Group A is more diverse, but has fewer pore systems in the
ventral area than group B, and this group tends to inhabit normal marine environments, while group B inhabits
brackish water. They also showed that the density of pore systems on the ventral surface of Loxoconcha species
is not determined by habitat adaptation, but by phylogeny. Several papers have been published on the ontogeny
of the genus Loxoconcha (Smith & Kamiya, 2003; Ishii et al., 2005; Le et al., 2016). Overall, they showed that the
ontogeny of species in this genus comprises eight stages, i.e. from instar A-7 to adult.
To date, no study has considered the change in the total pores on the carapace throughout the moult,
and then looked at the difference on this change among Group A species of the genus Loxoconcha. Therefore,
in this study, the total number of pores on the carapace as well as total number of anterior and posterior false
radial pores, are shown by instar. Based on these numbers, three subgroups of group A are suggested using
DDP analysis. This work will contribute to a more thorough understanding of the phylogeny of the genus
Loxoconcha, since the detailed taxonomy is essential for the accurate comparisons among species.
Material and Methods
Locat ions and date o f sampl ing . Material used in this study was collected along the eastern coast
of Japan from Obitsu estuary (Chiba Prefecture) to Miyazaky City (Miyazaky Prefecture) and around the
Okinawa Islands (fig. 1); the remaining ones were collected in USA (Goodwin Island, York River), Australia
Fig. 1. Maps of Japan showing location of the study areas from 2012 to 2015.
71Variation of Number of Pores on the Carapaces of Group A Species of the Genus Loxoconcha…
(Stanley, Tasmania; Tweed Head West), Thailand (Satun, Khlong Thom), England (Porth Costell, Holy Island;
Beaulieu river), Spain (Torre la sal), Libya (Toripoli) and Italy (Bay of Naples).
Method o f sampl ing and spec imen t rea tment . Samplings were carried out on reef slopes us-
ing SCUBA diving, on reef flats, tidal beaches and river mouths during low tide. At each sampling points, the
upper layer 5‒10mm of sediment, sea grass and sea algae were scooped into a plastic bottle using a spoon (a flat
spoon with dimensions of 12 × 15 cm or a rectangular spoon of 4 × 7 cm, depending on the degree of surface
irregularity). Then, all of the collected specimens were fixed in 5–10 % formaldehyde that had been neutralised
with hexamethylenetetramine before being washed through 16-mesh (# 1 mm) and 250-mesh (# 0.063 mm)
sieves. Part of the washed material was fixed with 70–80 % alcohol to observe the appendages, and the remain-
ing material was dried.
Morpholog ica l observa t ions and taxonomy. The specimens were dissected under a binocular
microscope in the laboratory. For the dissected specimens, soft parts were mounted on a slide glass in the “Neo
Sigaral” agent and carapaces were on a cardboard slide with single hole. Dried carapaces and individuals were
coated with gold using a quick auto-coater (JFC-1500, Ion Sputtering Device). After coating, the dried samples
were used to observe the pores on carapace with a Scanning Electron Microscope (JSM-5600LV, JEOL). SEM
photos were subsequently used for estimation of number of normal pores on the carapace, number of anterior
and posterior false radial pores using some computer software such as ImageJ, Adobe Photoshop (fig. 2).
Species were classified basing on morphology of carapaces, the chaetotaxy of appendages, muscle scars,
hinge elements etc. following Sars (1866) and Yassini & Jones (1995).
Most of the illustrated specimens were deposited in the collection of the Shizuoka University Museum
(SUM), identified by numbers with the prefix SUM-CO.
Div i s ion o f subgroups . Division of subgroups A1, A2 and A3 of group A of the genus Loxoconcha and
phylogenetic relationship among the species of this genus were estimated by Differentiation of Distributional
Pattern of Pore-system (DDP) analysis. This analysis of the carapace pore-systems was first proposed and
Fig. 2. Sketching of pore patterns of left valve in early diffirentation stage of some species of Group A of the genus
Loxoconcha, indicating normal pores, anterior and posterior false radial pores on carapace. Pores connected by
lines indicate false radial pores. Black solid and open circles mean twisted and smooth type pores, respectively.
Double circles for additional pores. Scale 100 μm.
72 D. D. Le
exemplified for the phylogenetic reconstruction of Ostracoda by Tsukagoshi (1990). He examined eleven
recent and three extinct species of Cythere and concluded that the interspecific differentiation in distributional
patterns of pore-systems on the carapace for later instars (A-2, A-1 and adult) reflected the phylogeny of the
genus Cythere. Then, Kamiya (1997) named the phylogenetic reconstructing method proposed by Tsukagoshi
(1990) “DDP analysis”, and applied it to determining the phylogenetic relationship among four families
(Leptocytheridae, Cytheridae, Loxoconchidae and Xestoleberidae) by the comparison of pores in the early
instars (A-6, A-5 and A-4). For the case of the genus Loxoconcha, Ishii et al. (2005) applied DDP analysis to find
the phylogenetic relationships among twelve species in group A and five species in group B.
Results and Discussions
Results of DDP analys is in phylogeny of Group A based on tota l pores
of carapace
The phylogeny of all twenty-eight recent species of Group A of the genus Loxoconcha
was examined by the DDP analysis. Figure 3 shows the result of the DDP analysis and table
1 shows total number of pore systems for each species and instar. All species have identical
number and same distributional pattern of pore system in and before the fifth instar (A-4).
The first differentiation of the pore pattern occurs in the sixth instar (A-3), and three pat-
T a b l e 1 . Total number of pore-systems of twenty-eight species of three subgroups of the genus
Loxoconcha following each species and instar (including anterior and posterior false radial pores)
No. Sub-
group Species
Molt instars (A-1, A-2, etc., in descending order
of size)
Aver-
age of
adultA-7 A-6 A-5 A-4 A-3 A-2 A-1 Adult
1 A1 Loxoconcha harimensis Okubo, 1980* 9 13 22 31 42 54 70 82 83.0
2 L. wilberti Puri, 1954 54 72 82
3 L. variolata Brady, 1878 82
4 L. hattorii Ishizaki, 1971* 54 72 83
5 L. kattoi Ishizaki, 1968* 54 72 83
6 L. tosaensis Ishizaki, 1968* 54 72 83
7 L. epeterseni Ishizaki, 1981* 54 72 83
8 L. kitanipponica Ishizaki, 1971* 54 72 83
9 L. zamia Ishizaki, 1968* 72 83
10 L. prolaeta Zhou, 1995* 83
11 L. noharai Le & Tsukagoshi, 2014 31 42 54 72 83
12 L. australis Brady, 1880 31 42 54 73 82
13 Loxoconcha sp. A 42 54 73 82
14 Loxoconcha sp. B 42 54 73 82
15 Loxoconcha sp. C 54 73 82
16 L. japonica Ishizaki, 1968* 9 13 22 31 42 54 73 83
17 L. lilljeborgii Brady, 1868* 22 31 42 54 73 83
18 L. matagordensis Swain, 1955 31 42 54 73 83
19 Loxoconcha sp. D 74 85
20 L. optima Ishizaki, 1968* 22 31 42 54 74 87
21 A2 Loxoconcha sp. E 55 74 84 87.5
22 L. tumida Brady, 1869 55 75 85
23 L. mutsuensis Ishizaki, 1971* 9 13 22 31 43 55 75 86
24 L. geometrica Bonaduce et al., 1976 76 87
25 L. bairdi Müller, 1912 43 55 76 89
26 L. stellifera Müller, 1894 55 77 90
27 L. rhomboidea Fischer, 1855 31 43 55 78 91
28 A3 L. elliptica Brady, 1868 31 44 56 77 90 90.0
* Data of these species are after Ishii et al. (2005)
73Variation of Number of Pores on the Carapaces of Group A Species of the Genus Loxoconcha…
terns are recognised. The differences among the three patterns are caused by one or two
additional pores that discriminate the three pore patterns. In each pattern, there is no fur-
ther differentiation among species appears at A-2 instar. However, further differentiation
branching within each of the three are recognised in the instar A-1 and adult.
The results of the DDP analysis (fig. 3) indicate that there are three phyletic lineages
in the recent species of Group A of the genus Loxoconcha. The three phyletic lineages are
defined in this study as subgroups A1, A2 and A3, respectively. Subgroup A1 contains nine-
teen species, which have 42 pores in the A-3 instar. Subgroup A2 contains seven species
with 43 pores in the A-3 instar. Subgroup A3 includes only one species, L. elliptica, which
has 44 pores in the A-3 instar.
In A-3 and A-2 instars, there is no difference in normal pores and anterior false radial
pores (fig. 2). The difference of one or two pores in total is caused by those in posterior false
Fig. 3. Phylogenetic relationship between recent twenty-seven species of Group A of the genus Loxoconcha,
estimated by DDP analysis. Numerals indicate total number of pore system for each lineage and instar.
74 D. D. Le
radial pores (fig. 2). Only a few pores in the restricted area discriminate subgroups A1 from
A2 or A2 from A3.
Variat ion of fa lse radia l pores of the three subgroup A1, A2 and A3
Group A species of the genus Loxoconcha has unique characters, the false radial pores
(Ishii, 2004). Table 2 shows clear number of anterior and posterior false radial pores for
each subgroup from instar A-3 to adult. There is no difference in number of anterior false
radial pores among all thirty species for each stage, e.g., six in A-3 instar, nine in A-2 instar,
ten in A-1 instar and eleven in adult. Each subgroup possesses a certain number of posteri-
or false radial pores in A-3 and A-2 instars. Subgroup A1 has three, A2 has four and A3 has
five posterior false radial pores in the instar A-3 as well as in the instar A-2. In the next A-1
instar and adult, some varieties within each subgroup and the overlap between subgroups
are found, although each subgroup possesses almost common numbers in posterior false
radial pores; in adult, subgroup A1 has five or six; A2 has six, seven or eight; A3 has eight.
No increase through A-3/A-2 instar and A-1 instar/adult molting is found in all species in
number of posterior false radial pores.
T a b l e 2 . Number of anterior and posterior false radial pores of thirty species belonging to three
subgroups of the genus Loxoconcha
No. Subg-
roup Species A-3 instar A-2 instar A-1 instar Adult
An. Po. An. Po. An. Po. An. Po.
1 A1 Loxoconcha harimensis 6 3 9 3 10 5 11 5
2 L. wilberti 6 3 9 3 10 5 11 5
3 L. variolata 11 5
4 L. hattorii 9 3 10 5 11 5
5 L. kattoi 9 3 10 5 11 5
6 L. tosaensis 9 3 10 5 11 5
7 L. epeterseni 9 3 10 5 11 5
8 L. kitanipponica 9 3 10 5 11 5
9 L. zamia 10 5 11 5
10 L. prolaeta 11 5
11 L. noharai 6 3 9 3 10 5 11 5
12 L. australis 6 3 9 3 10 5 11 5
13 Loxoconcha sp. A 6 3 9 3 10 5 11 5
14 Loxoconcha sp. B 6 3 9 3 10 5 11 5
15 Loxoconcha sp. C 9 3 10 5 11 5
16 L. cumulus 11 5
17 L. variolata 11 5
18 L. japonica 6 3 9 3 10 5 11 5
19 L. lilljeborgii 6 3 9 3 10 5 11 5
20 L. matagordensis 6 3 9 3 10 6 11 6
21 Loxoconcha sp. D 10 6 11 6
22 L. optima 6 3 9 3 10 6 11 6
23 A2 Loxoconcha sp. E 9 4 10 6 11 6
24 L. tumida 9 4 10 7 11 7
25 L. mutsuensis 6 4 9 4 10 7 11 7
26 L. geometrica 10 8 11 8
27 L. bairdi 6 4 9 4 10 8 11 8
28 L. stellifera 9 4 10 8 11 8
29 L. rhomboidea 6 4 9 4 10 8 11 8
30 A3 L. elliptica 6 5 9 5 10 8 11 8
Abbrev ia t ions : An. — Anterior false radial pore; Po. — Posterior false radial pore.
75Variation of Number of Pores on the Carapaces of Group A Species of the Genus Loxoconcha…
Most species of subgroup A2 have higher total number of the pore-system than the
species of subgroup A1 in the A-1 instar and adults (tables 1 and 2). Not only additional
posterior false radial pores but also additional normal pores cause clear differences between
subgroup A1 and A2 in the last two stages (A-1 instar and adult).
Interspeci f ic re lat ionships within Group A of the genus Loxoconcha
and their geographical dis tr ibut ions
The geographical distribution of the twenty-eight recent species of Group A of Loxo-
concha examined by the DDP analysis was compiled in this study (table 3). Species of sub-
groups A2 and A3 occur mainly along the Atlantic coasts of Europe, North Africa and the
T a b l e 3 . Distributional areas of twenty-eight recent species of three subgroups of the genus Loxoconcha
in Japan and other areas
No. Sub-
group Species name Recent distributional areas Source
1 A1 Loxoconcha harimensis Japan coast (except for Hokkaido and Ryukyu Islands) 1
2 L. hattorii Japan coast (except for Ryukyu Islands) 1
3 L. kattoi Japan coast (except for Hokkaido and Ryukyu Islands) 1
4 L. tosaensis Japan coast (Eastern coast of Hokkaido in the northern
end and excepts for Ryukyu Islands)
1
5 L. epeterseni Japan coast (except for Hokkaido and Ryukyu Islands) 1
6 L. kitanipponica Japan coast (except for Hokkaido and Ryukyu Islands) 1
7 L. zamia Japan coast (except for Hokkaido and Ryukyu Islands) 1
8 L. prolaeta Tsukumo Bay, Japan 2
9 L. japonica Japan coast (this study), southern part of Korean Peninsula
(including Cheju island) and Hong Kong
1 & 3
10 L. optima Japan coast (except for Ryukyu Islands) 1
11 L. noharai Okinawa Islands, Southern Japan 1
12 L. lilljeborgii Japan coast, Philippines, Thailand and northern part
of Australia, Nha Trang MPA of central Vietnam,
throughout the Indian Ocean
1 & 3
13 Loxoconcha sp. C Khlong Thom and Satun in the west coast Thailand 2
14 Loxoconcha sp. D Khlong Thom and Satun in the west coast Thailand 2
15 L. variolata Port Phillip Bay, Victoria, Australia, Common in Bass
strait, Australia
4 & 5
16 L. australia Australian Coast 6
17 Loxoconcha sp. A Stanley, Tasmania, Australia 2
18 Loxoconcha sp. B Cowell Bay, Supencer Gulf, South Australia 2
19 L. wilberti West coast of Florida, Belize, southwestern coast of
Panama
7–9
20 L. matagordensis Mexico, Texas and Florida in the gulf of Mexico; on the
Atlantic coast of north Carolina, Varginia and New Jersey
10
21 A2 Loxoconcha sp. E Toripoli, Lybya 2
22 L. tumida Common throughout the Mediterranean 11
23 L. mutsuensis Japan coast (except for Hokkaido and Ryukyu Islands) 1
24 L. geometrica Toripoli, Libya; Adriatic Sea 11
25 L. bairdi Adriatic Sea, Tunisian Shelf 11
26 L. stellifera Common throughout the Mediterranean 11
27 L. rhomboidea Carary Island in the south of the Atlantic, Adriatic Sea and
Tuunisian Shelf in the Mediterranean
11, 12
28 A3 L. elliptica Northwest Europe and whole of the Mediterranean 12
Note . 1 — this study; 2 — Ishii (2004); 3 — Tanaka & Ikeya (2002); 4 — McKenzie (1967); 5 — Yassini &
Jones (1995); 6 — Ikeya (1997); 7 — Puri (1960); 8 — Teeter (1975); 9 — Puri & Hulings (1957); 10 — Garbett
& Maddocks (1979); 11 — Bonaduce et al. (1992); 12 — Athersuch et al. (1989).
76 D. D. Le
Mediterranean. The only exception is Loxoconcha mutsuensis Ishizaki, 1971, which also
occurs along the coasts around Japan. Subgroup A1 species are distributed along the Atlan-
tic coasts of Northern and Central America, the coasts of East and Southeast Asia, and the
coasts around Australia. Therefore, the probable geographical distribution of subgroup A1
by bridging the gaps between the confirmed distribution ranges of the Pan-Indian area, the
Pan-Pacific area (except for South America) and the Atlantic coasts of North and Central
America (Ishii, 2004; Ishii et al., 2005). In particular, species of subgroup A1 of the genus
Loxoconcha can be distributed all over the World except for the distribution areas of sub-
groups A2 and A3 of this genus. There are no data for all coasts of South America and most
coasts of Africa due to lack of specimens from these areas.
Hypothesis of or ig in of subgroup A
Data from the table 1 and table 2 show that total number of pores on carapace as well
as total number of posterior false radial pores are highest in the subgroup A3, median in the
subgroup A2 and lowest in the subgroup A1.
Loxoconcha nozokiensis Ishizaki, 1963 has five posterior false pores in aldult (fig. 4),
thus this species proved to belong to subgroup A1 and has been known as one of the old-
est Loxoconcha species in Japan. The oldest records of L. nozokiensis are from the early
Miocene Akeyo Formation, Mizunmani Group and Toyama Formation, Iwamura Group,
central Japan (ca. 18 Ma) (Ishizaki, 1963; Ishii, 2004; Irizuki et al., 2004; Le, 2015).
Loxoconcha hastata Brady, 1869 has seven posterior false radial pores (fig. 4), this spe-
cies is classified in subgroup A2. Up to now, the oldest fossil record of the subgroup A2 has
belonged to L. hastata, this specimen is from the Early Middle Miocene (Langhian), Czech
Republic (ca. 16 to 16.5 Ma) (Ishii, 2004). The lack of specimen before this age as well as
the lack of fossil specimens of the subgroup A3 hindered further research. However, from
the trend of the total number of pores of the three subgroups (tables 1 and 2) and the fossil
record, the geological age of subgroup A1 is the oldest, followed by subgroups A2 and A3.
Due to the lack of fossil species of the subgroup A3, the following hypothesis has been made
concerning origin of subgroup A2. Subgroup A2 may be established after the appearance
of the Paleo-Mediterranean Sea resulted from the plate-tectonic event that caused the con-
tinent of Africa continent to converge with the continent of Eurasia (Early Miocene) (Ishii,
2004). The distribution of subgroup A2 species concentrated in Europe and the Mediter-
ranean coasts and the oldest age datum (16 to 16.5 Ma) clarified in this study support the
Fig. 4. Distributional patterns of pore-systems of left valve in adult: A — L. nozokiensis, B — L. hastata. Pores
connected by lines indicate false radial pores. Scale 100 μm.
77Variation of Number of Pores on the Carapaces of Group A Species of the Genus Loxoconcha…
hypothesis (Ishii, 2004; Ishii et al., 2005). The hypothesis suggests that subgroup A2 may be
possibly derived from subgroup A1.
Conclusion
This study focused on examining the phylogeny of all twenty-eight existing species
within Group A of the genus Loxoconcha. These specimens were collected from various
locations, including the east coast of Japan spanning from the Obitsu estuary in Chiba
Prefecture to Miyazaky City in Miyazaky Prefecture, around the Okinawa Islands; Good-
win Island, York river in the USA; Stanley, Tasmania, Tweed Head West in Australia; Sat-
un, Khlong Thom in Thailand; Porth Costell, Holy Island; Beaulieu River in England; Torre
La Sal in Spain; Toripoli in Libya and the Bay of Naples in Italy. Based on the total number
of pores on the carapace, three subgroups A1, A2 and A3 of Group A were introduced by
using DDP analysis. The clear difference in the total number of pores on carapaces among
the three subgroups is established from A-3 instar to adult. In the instar A-3, these numbers
of subgroup A1, A2 and A3 are 42, 43 and 44 respectively.
There is an identical number of anterior false radial pores among the subgroups in all
instars. However, the difference in the number of posterior false radial pores among three
subgroups is found from instar A-3. In this instar, these numbers of subgroups A1, A2 and
A3 are equal to 3, 4 and 5.
Species of subgroup A1 are distributed throughout the World except the distributional
areas of subgroups A2 and A3. Meanwhile, the species of subgroups A2 and A3 live mainly
in Atlantic coasts of Europe, North Africa and the Mediterranean.
Declaration of competing interest
The authors declare that they have no known competing financial interests or personal relationships that
could appear to have influenced the work reported in this paper.
Declaration of funding
This research has not received any specific funding.
Acknowledgements
First of all, I would like to express my deepest gratitude and sincere thanks to my supervisor, Prof. Akira
Tsukagoshi, for his continuous support to my research, for his guidance, enthusiasm and helpful suggestions.
I thank Prof. Takahiro Kamiya and Dr. Tohru Ishii (Kanazawa University) for their invaluable advice and
continuous encouragement. I also appreciate Dr. Hayato Tanaka (Tokyo Sea Life Park) and all members of
the Ostracod Research Team of Shizuoka University for helpful comments and assistance. Finally, I am deeply
grateful to the editor and the reviewers who carefully reviewed my manuscript.
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Received 23 August 2023
Accepted 1 February 2024
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| id | oai:ojs.akademperiodyka.org.ua:article-544 |
| institution | Zoodiversity |
| issn | 2707-7268 |
| keywords_txt_mv | |
| language | English |
| last_indexed | 2026-08-21T01:01:38Z |
| publishDate | 2023 |
| publisher | Publishing House "Akademperiodyka" of the National Academy of Sciences of Ukraine |
| record_format | ojs |
| resource_txt_mv | ojsakademperiodykaorgua/9b/16a2b14dac0dc60b928fd0252a19859b.pdf |
| spelling | oai:ojs.akademperiodyka.org.ua:article-5442026-08-20T12:37:09Z Variation of Number of Pores on the Carapaces of Group A Species of the Genus Loxoconcha (Crustacea, Ostracoda) Following the Molting Le, D. D. Crustacea Ostracoda Loxoconcha classification phylogeny morphology Phylogeny of all extant twenty-eight species of Group A of the genus Loxoconcha are examined in this study. Basing on the total number of pores on carapaces, three species subgroups of this genus are shown by Differentiation of Distributional pattern of Pore-system (DDP) analysis. All species possess identical number and same distributional pattern of pore-system in and before A-4 instar. The difference in the total number of pores on carapaces is found from the instar A-3 to adult and thus three patterns are recognized. In the instar A-3, these numbers of subgroup A1, A2 and A3 are 42, 43 and 44, respectively. Additionally, the present study shows an identical number of anterior false radial pores among the subgroups at all instars. However, the number of posterior false radial pores is different among three subgroups from A-3 instar. In this instar, these numbers of subgroup A1, A2 and A3 are equivalent to 3, 4 and 5. By combination of this study and previous studies, geographical distribution of three subgroups is shown. Species of subgroup A1 distribute worldwide except the distributional areas of subgroups A2 and A3. While, species of subgroup A2 and A3 only reside in Atlantic coasts of Europe, northern Africa and coasts of the Mediterranean Sea. Publishing House "Akademperiodyka" of the National Academy of Sciences of Ukraine 2023-11-30 Article Article application/pdf https://ojs.akademperiodyka.org.ua/index.php/Zoodiversity/article/view/544 10.15407/zoo2024.01.069 Zoodiversity; Vol. 58 No. 1 (2024): Zoodiversity Zoodiversity (Vestnik Zoologii); Том 58 № 1 (2024): Zoodiversity 2707-7268 2707-725X 10.15407/zoo2024.01 en https://ojs.akademperiodyka.org.ua/index.php/Zoodiversity/article/view/544/249 Copyright (c) 2023 Doan Dung Le |
| spellingShingle | Le, D. D. Variation of Number of Pores on the Carapaces of Group A Species of the Genus Loxoconcha (Crustacea, Ostracoda) Following the Molting |
| title | Variation of Number of Pores on the Carapaces of Group A Species of the Genus Loxoconcha (Crustacea, Ostracoda) Following the Molting |
| title_full | Variation of Number of Pores on the Carapaces of Group A Species of the Genus Loxoconcha (Crustacea, Ostracoda) Following the Molting |
| title_fullStr | Variation of Number of Pores on the Carapaces of Group A Species of the Genus Loxoconcha (Crustacea, Ostracoda) Following the Molting |
| title_full_unstemmed | Variation of Number of Pores on the Carapaces of Group A Species of the Genus Loxoconcha (Crustacea, Ostracoda) Following the Molting |
| title_short | Variation of Number of Pores on the Carapaces of Group A Species of the Genus Loxoconcha (Crustacea, Ostracoda) Following the Molting |
| title_sort | variation of number of pores on the carapaces of group a species of the genus loxoconcha (crustacea, ostracoda) following the molting |
| topic_facet | Crustacea Ostracoda Loxoconcha classification phylogeny morphology |
| url | https://ojs.akademperiodyka.org.ua/index.php/Zoodiversity/article/view/544 |
| work_keys_str_mv | AT ledd variationofnumberofporesonthecarapacesofgroupaspeciesofthegenusloxoconchacrustaceaostracodafollowingthemolting |