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Halocyprid Ostracods of the Arabian Sea Region

Authors:
  • A.O. Kovalevsky Institute of Biology of the Southern Seas of RAS

Abstract and Figures

The taxonomy and distribution of halocyprid ostracods from the Arabian Sea Region is reported, based upon samples collected in the Northwestern Indian Ocean within the framework of the Netherlands Indian Ocean Program (NIOP: 1992-1993), the U.S. Joint Global Ocean Flux Study (U.S. JGOFS: 1994–1996), and the U.S. Global Ocean Ecosystem Dynamics program (U.S. GLOBEC: 1995). Forty-one species from the following genera belonging to the family Halocyprididae are described, illustrated, and representative photographs are presented: Archiconchoecia, Alacia, Conchoecetta, Conchoecia, Conchoecilla, Conchoecissa, Discoconchoecia, Loricoecia, Mikroconchoecia, Orthoconchoecia, Paraconchoecia, Paramollicia, Platyconchoecia, Porroecia, Proceroecia, Pseudoconchoecia, Clausoecia, Kyrtoecia, Nasoecia and Euconchoecia. For fourteen species, members of the genera Macroconchoecia, Mollicia, Paraconchoecia, Metaconchoecia, Mülleroecia, Fellia, Halocypria and Halocypris, only carapace outlines are presented. Keys to the subfamilies, tribes, genera and species, and patterns of horizontal and vertical distribution of each described species in the Arabian Sea Region are also given. The data on occurrence of halocyprid species at each of the stations during the investigation period and the depth ranges of halocyprid species found in the analyzed material but not described in the present book are listed in appendices.
Content may be subject to copyright.
The taxonomy and distribution of halocyprid ostracods from the Arabian Sea Region is
reported, based upon samples collected in the Northwestern Indian Ocean within the framework
of the Netherlands Indian Ocean Program (NIOP: 1992-1993), the U.S. Joint Global Ocean Flux
Study (U.S. JGOFS: 1994–1996), and the U.S. Global Ocean Ecosystem Dynamics program
(U.S. GLOBEC: 1995).
Forty-one species from the following genera belonging to the family Halocyprididae are
described, illustrated, and representative photographs are presented: Archiconchoecia, Alacia,
Conchoecetta, Conchoecia, Conchoecilla, Conchoecissa, Discoconchoecia, Loricoecia, Mikro-
conchoecia, Orthoconchoecia, Paraconchoecia, Paramollicia, Platyconchoecia, Porroecia,
Proceroecia, Pseudoconchoecia, Clausoecia, Kyrtoecia, Nasoecia and Euconchoecia. For
fourteen species, members of the genera Macroconchoecia, Mollicia, Paraconchoecia,
Metaconchoecia, Mülleroecia, Fellia, Halocypria and Halocypris, only carapace outlines are
presented. Keys to the subfamilies, tribes, genera and species, and patterns of horizontal and
vertical distribution of each described species in the Arabian Sea Region are also given. The
data on occurrence of halocyprid species at each of the stations during the investigation period
and the depth ranges of halocyprid species found in the analyzed material but not described in
the present book are listed in appendices.
Keywords: Ostracoda, Halocyprididae, Taxonomy, Distribution, Arabian Sea Region.
Acknowledgements
We thank our colleagues Martien A. Baars from the Netherlands Institute for Sea Research
(Texel, the Netherlands), Peter B. Ortner formerly from the U.S. National Oceanographic and
Atmospheric Administration’s Atlantic Oceanographic and Meteorology Laboratory (Miami,
USA) and now at The Rosenstiel School at the University of Miami (Miami, USA), and Karen
Wishner from the University of Rhode Island for allowing us to work with some of their samples.
Richard Barber, Carin Ashjian, Charles Flagg and Louis Codispoti helped us understand the
regional dynamics; Peter Lane (formerly with The Rosenstiel School, Miami, USA) provided
excellent cooperation in both the eld and laboratory work. We express our great appreciation to
Martin V. Angel (Southampton, UK) for his support and valuable advice during the work on the
descriptions of ostracod species.
We are indebted to our colleagues from the Institute of Biology of the Southern Seas (IBSS,
Ukrainian Academy of Science, Sevastopol, Ukraine): Irina Prusova for her close cooperation
during the entire period of the manuscript preparation; Valentina Moryakova for her help in the
sample analyses; Olga Akimova for her help in obtaining the necessary literature. Special thanks
are due to the administration of the IBSS, especially its deputy director Alexander Boltachev, for
supporting and encouraging this work.
We also owe a considerable debt of gratitude to both of our reviewers.
Funding for the eldwork and sample analyses was provided by the Netherlands Marine
Research Foundation (SOZ), the U.S. National Science Foundation (NSF) and the U.S. Of ce
of Naval Research (ONR). Ship operation support came from SOZ, NSF and ONR.
Halocyprid Ostracods of the Arabian Sea Region 5
CONTENTS
Page
INTRODUCTION ..………………………………………..……..…………..……..…... 7
MATERIALS AND METHODS ..…………………………….………….……...….…… 8
Sampling data .……………………………………………………….………….….. 8
Laboratory analysis ..……………………………………………………………..…. 12
Data analysis: Maps and diagrams ..…………………………………………..…….. 13
MORPHOLOGY OF THE HALOCYPRID OSTRACODS ...…..……..……….……..... 14
ABBREVIATIONS used in the descriptions, gures and keys .………….……………... 20
SYSTEMATIC ACCOUNT....……………………….…………...……………..……….. 21
Family Halocyprididae Dana, 1853 ..……………………………………...………. 23
Subfamily Archiconchoeciinae Poulsen, 1969 ..…..………….……………….. 23
Genus Archiconchoecia Müller, 1894 ..………………………...……….. 23
Subgenus A. (Archiconchoecia) Chavtur & Stovbun, 2003 ....……... 23
Archiconchoecia (Archiconchoecia) striata Müller, 1894
..…... 24
Subfamily Conchoeciinae Müller, 1912 ……………………………..………… 28
Tribe Conchoeciini Chavtur & Angel, 2011 ………....................................... 28
Genus Alacia Poulsen, 1973 ..……….……………………………...…….
36
Alacia alata (Müller, 1906) .……….….……...…………..……. 37
Alacia leptothrix (Müller, 1906) ..……….……………..………. 41
Genus Conchoecetta Claus, 1890 ....………………………………..……. 44
Conchoecetta acuminata Claus, 1890 ..……………………….. 45
Conchoecetta giesbrechti (Müller, 1906) ………………...…..... 49
Genus Conchoecia Dana, 1849 ..……………..…………………..………
53
Conchoecia lophura Müller, 1906 ……………………..…..….. 54
Conchoecia macrocheira Müller, 1906 ...….…………..…..….. 58
Conchoecia magna Claus, 1874
..….……………………....…... 61
Genus Conchoecilla Claus, 1890 ..……………………………………….. 65
Conchoecilla daphnoides Claus, 1890 ...………………………. 65
Genus Conchoecissa Claus, 1890 .....………..……………………..…….. 69
Conchoecissa imbricata (Brady, 1880) ...…………………...…. 70
Conchoecissa plinthina (Müller, 1906) .………………………. 74
Genus Discoconchoecia Martens, 1979 ..……….…….…………..……… 77
Discoconchoecia discophora (Müller, 1906) ...……..………..... 78
Discoconchoecia aff. elegans (Sars, 1865) ..….………...….….. 82
Discoconchoecia tamensis (Poulsen, 1973) ………...…………. 86
Genus Loricoecia Poulsen, 1973 ..…………..…………………..……….. 90
Loricoecia loricata (Claus, 1894) ..……….…………...……….
90
Genus Mikroconchoecia Claus, 1890 ...………………………………….
94
Mikroconchoecia curta s.l. (Lubbock, 1860) ...…..……..…….. 95
Mikroconchoecia stigmatica (Müller, 1906) .…………………. 100
Genus Orthoconchoecia Granata & Caporiacco, 1949 ..……......……….. 104
Orthoconchoecia atlantica (Lubbock, 1856) ...…..….………… 105
Orthoconchoecia striola s.s. (Müller, 1906) ..…...……..……… 109
6 Inna Drapun & Sharon L. Smith
Genus Paraconchoecia Claus, 1890 .......…..………………………......... 113
Paraconchoecia allotherium (Müller, 1906) ......……………... 115
Paraconchoecia echinata (Müller, 1906) ..…………...……….. 119
Paraconchoecia inermis Claus, 1890 ..……………..….……… 123
Paraconchoecia oblonga Claus, 1890, form A ..….…………… 127
Paraconchoecia oblonga Claus, 1890, form B ..……………… 131
Genus Paramollicia Poulsen, 1973 .………………………………….….
135
Paramollicia dichotoma (Müller, 1906) …………....…………. 135
Genus Platyconchoecia Poulsen, 1973 ..………….……….…………….. 139
Platyconchoecia prosadene (Müller, 1906) ...…….…………... 139
Genus Porroecia Martens, 1979 .....…………….………………………..
143
Porroecia parthenoda (Müller, 1906) ……….………………… 144
Porroecia porrecta (Claus, 1890) ...…………..….……………. 148
Porroecia spinirostris (Claus, 1874) ..…...………….………… 152
Genus Proceroecia Kock 1992 ...………………………….…………….. 156
Proceroecia brachyaskos (Müller, 1906) .……..……………… 158
Proceroecia decipiens (Müller, 1906) .……….………..……… 162
Proceroecia macroprocera (Angel, 1971) ..……...…………… 166
Proceroecia microprocera (Angel, 1971) ..……...……………. 170
Proceroecia procera (Müller, 1906) ..……………..…………... 174
Genus Pseudococnchoecia Claus, 1890 ..………………………………..
178
Pseudococnchoecia concentrica (Müller, 1906) ..…………..… 178
Tribe Metaconchoeciini Chavtur & Angel, 2011 ...………………………… 182
Genus Clausoecia Chavtur & Angel, 2011 ..….…………………………. 184
Clausoecia pusilla (Müller, 1906) .....…………………………. 184
Genus Kyrtoecia Chavtur & Angel, 2011 ...…..………………...………... 188
Kyrtoecia kyrtophora (Müller, 1906) ………………..……….... 188
Genus Nasoecia Chavtur & Angel, 2011 ...……………………………… 192
Nasoecia nasotuberculata (Müller, 1906) ..…………...………. 192
Subfamily Euconchoeciinae Poulsen, 1969 ......……………………..………… 196
Genus Euconchoecia Müller, 1891 ....………..………………………….. 196
Euconchoecia cf. aculeata (Scott, 1894) ......…....……………..
198
Euconchoecia aff. aculeata elongata Müller, 1906 …………...
202
Euconchoecia cf. chierchiae Müller, 1891 ..….………………. 206
Subfamily Halocypridinae Claus, 1890 ...…………………………..………… 210
LITERATURE CITED .…………………………………….……………...……..…….. 212
APPENDICES ..……………………………………………………………….…….….. 215
Appendix 1 …………………………………………………………………...…….. 217
Appendix 2 ……………………………………………………...……………….…. 218
Halocyprid Ostracods of the Arabian Sea Region 7
INTRODUCTION
“Planktonic ostracods constitute an appreciable part of marine zooplankton, especially
in tropical and subtropical oceans. This group from the Indian Ocean has not been studied
in detail although extensive studies have been made on them from other oceans, particularly
the Atlantic. Müllers report (1906) based on the “Valdivia” material was the rst study on
planktonic ostracods from the Indian Ocean. Cannon (1940) gave a list of planktonic ostracods
collected during the John Murray Expedition. Later, Leveau (1969), George (1969, 1971, 1976
and 1977), George, Purushan and Madhupratap (1975) and James (1972 and 1973) reported
on this group. Poulsen’s studies (1962, 1965, 1969 and 1973) on the Dana material are very
exhaustive but the expedition covered limited areas of the Indian Ocean.” (Cited from George
& Nair, 1980, p. 29). This report by George & Nair (1980) is one of few investigations showing
the distributions of Indian Ocean ostracod species (thirty-two species) in the Arabian Sea Region
and other areas of the northern Indian Ocean. Their data are based on tows in the upper water
layer, and unfortunately descriptions of species are absent in this work.
In the 1990’s, a series of multidisciplinary oceanographic expeditions were carried out
in the Northwestern Indian Ocean by the Netherlands (Netherlands Indian Ocean Program,
NIOP: 1992–1993), the United Kingdom (Arabesque: 1994), Germany (Joint Global Ocean
Flux Study, JGOFS: 1995, 1997), Pakistan (North Arabian Sea Environmental and Ecological
research, NASEER: 1992–1994), India (JGOFS: 1995–1997) and the United States (JGOFS:
1994–1996; Global Ocean Ecosystems Dynamics Program, GLOBEC: 1995). These
investigations have resulted in more than 120 publications that address different aspects of
the biogeochemistry and physical forcing of the Arabian Sea Region (Watts et al., 2002).
Data on halocyprid ostracods, based on the zooplankton materials collected during these
expeditions, has not been published earlier.
The goals of this work are to report halocyprid ostracod species identi ed from the
zooplankton samples collected in the Arabian Sea Region within the framework of the NIOP
(1992–1993), the U.S. JGOFS (1994–1996) and the U.S. GLOBEC (1995), and to produce
a scholarly up-dated, yet easy-to-use identi cation guide for halocyprid ostracods of the
Arabian Sea Region.
Taxonomic analyses of the samples were made at the Institute of Biology of the Southern
Seas (IBSS) of the National Academy of Sciences of Ukraine. A total of 889 samples have
been analyzed and sixty-six species of halocyprid ostracods have been identi ed (six of them
only to the genus status). Unfortunately, because of different reasons, not all halocyprid species
are described and illustrated in this book. For forty-one species, a short description, detailed
original line drawings and photographs of female and male (only male or female in four species)
are given. For the fourteen other species, only carapace outlines are presented. Keys to the
subfamilies, tribes, genera and species, and maps and diagrams demonstrating horizontal and
vertical occurrence of the described species in the investigated area are also provided. The data
on occurrence of halocyprid species at each of the stations during the investigation period and
the depth ranges of species found in the analyzed material but not described in the present book
are listed in appendices.
8 Inna Drapun & Sharon L. Smith
MATERIALS AND METHODS
Sampling data
The reported material is based on samples collected within the framework of the Netherlands
Indian Ocean Program (NIOP; Project B: Monsoons and pelagic systems; aboard the R/V Tyro
during the cruise B2 in 1993), the U.S. Joint Global Ocean Flux Study (U.S. JGOFS; aboard
the R/V Thomas G. Thompson during the cruises TN039, TN043, TN045, TN050 and TN054
in 1994–1995) and the U.S. Global Ocean Ecosystems Dynamics Program (GLOBEC; Arabian
Sea Expedition; aboard the NOAA ship R/V Malcolm Baldrige during the cruises MB9503 and
MB9506 in 1995) in the Northwestern Indian Ocean. Locations of sampling stations are shown
in Fig. 1. Pertinent data for the samples are given in Table 1.
Fig. 1. Locations of sampling stations. Abbreviations are explained in Table 1.
In the NIOP cruise, zooplankton were sampled by a Hydrobios Multinet equipped with
nets of mesh size 200 μm (Table 1). In Multinet sampling, target depths were usually 500–200,
200–150, 150–100, 100–50 and 50–0 m. (Baars, 1994).
In the U.S. JGOFS cruises, zooplankton sampling was accomplished using a 1m
2
MOCNESS (Multiple Opening/Closing Net and Environmental Sensing System), a 0.25 m
2
MOCNESS and Bongo nets. The 1m
2
-mouth area MOCNESS and 0.6 m-diameter Bongo
net frame were tted with 153 μm mesh nets, while the 0.25 m
2
-mouth area MOCNESS was
tted with 64 μm mesh nets. In the 1m
2
-mouth area MOCNESS sampling, target depths on
the cruise TN039 were usually 1500–1000, 1000–500, 500–300, 300–200, 200–150, 150–100,
100–50 and 50–0 m; on the cruises TN043, TN045, TN050 and TN054 target depths were
1000–900, 900–800, 800–700, 700–600, 600–500, 500–400, 400–300, 300–250, 250–200,
200–150, 150–100, 100–75, 75–50, 50–25 and 25–0 m. Standard sampling depths during the
6
2
Halocyprid Ostracods of the Arabian Sea Region 9
Table 1. Summary of the sampling data: List of the stations from which material was analyzed.
Cruise /
Net type /
Net mesh
Station Standard
station
Station
symbol
in Fig.1
Tow
No
Latitude
(N)
Longitude
(E)
Date
(mm.dd)
Local
time
(start)
Depth
of tow
(m,
max)
Qty
of
sam-
ples
1993
Tyro B2 /
Multinet /
200 μm
SB4 SB4 –01.10 54.54 01.12 17:40 497 4
SB3 SB3 01.90 53.60 01.13 14:45 500 5
SB2 SB2 06.26 52.51 01.16 16:00 488 5
SB2 SB2 06.26 52.51 01.16 19:45 504 4
US1 US1 07.83 50.56 01.18 19:00 501 5
US1 US1 07.83 50.56 01.19 06:45 497 5
SI SI 12.04 54.95 01.24 15:30 493 5
SI SI 12.04 54.95 01.24 19:30 495 5
NWS NWS 12.86 52.44 01.26 06:10 494 5
1994
TN039 /
MOCNESS 1m
2
/
153 μm
2 TN2 1 06.00 78.54 09.23 16:34 997 8
6 TN6 2 08.04 64.99 09.26 22:49 1465 8
8 S15 S15 3 10.04 65.02 09.27 15:52 1500 8
10 S13 S13 4 12.09 65.03 09.28 10:52 1492 8
12 S11 S11 5 14.50 65.01 09.29 05:33 1500 8
14 N11 N11 6 15.42 68.74 09.30 08:59 1496 8
16 N9 N9 7 17.36 67.92 10.01 02:19 1500 8
18 N7 N7 8 19.05 67.00 10.01 17:34 997 8
18 N7 N7 9 19.04 67.00 10.02 05:43 1000 8
21 N4 N4 10 21.16 63.50 10.04 04:44 1500 8
23 N2 N2 11 22.42 61.17 10.05 10:11 1500 8
1995
TN043 /
MOCNESS 1m
2
/
153 μm
2 N2 N2 1 22.49 61.18 01.09 05:52 102 4
7 N7 N7 2 19.15 67.25 01.12 12:12 600 9
7 N7 N7 3 19.13 67.16 01.12 23:13 301 7
11 N11 N11 4 15.48 68.76 01.13 11:44 374 8
13 S15 S15 5 10.01 64.90 01.17 12:26 294 8
13 S15 S15 6 10.00 64.90 01.17 22:06 299 8
17 S11 S11 7 14.45 65.00 01.20 20:35 298 8
17 S11 S11 8 14.52 65.05 01.21 13:13 299 8
21 S7 S7 9 16.11 62.10 01.23 21:04 303 8
21 S7 S7 10 16.10 62.12 01.24 12:13 303 8
26 S4 S4 12 17.32 59.81 01.27 11:51 298 8
26 S4 S4 13 17.47 59.87 01.28 22:12 298 8
27 S3 S3 14 17.82 58.98 01.28 21:44 300 8
27 S3 S3 15 17.75 58.94 01.29 10:04 297 8
28 S2 S2 16 18.12 58.09 01.29 21:55 299 8
28 S2 S2 17 18.14 58.04 01.30 12:28 298 8
TN043 /
BONGO /
153 μm
2 N2 N2 1 22.48 61.18 01.09 10:00 183 1
4 N4 N4 2 21.19 63.55 01.10 11:33 201 1
6 N6 N6 3 19.89 65.89 01.11 12:33 250 1
9 N9 N9 4 17.30 67.93 01.14 08:09 200 1
15 S13 S13 5 12.07 64.99 01.19 15:33 288 1
18 S10 S10 6 14.84 64.25 01.22 10:01 174 1
19 S9 S9 7 15.28 63.52 01.22 18:32 262 1
20 S8 S8 8 15.64 62.77 01.23 04:48 268 1
21 S7 S7 9 16.03 62.02 01.23 16:57 204 1
10 Inna Drapun & Sharon L. Smith
Table 1 – continued
Cruise /
Net type /
Net mesh
Station Standard
station
Station
symbol
in Fig.1
Tow
No
Latitude
(N)
Longitude
(E)
Date
(mm.dd)
Local
time
(start)
Depth
of tow
(m,
max)
Qty
of
sam-
ples
1995
TN043 /
BONGO /
153 μm
24 S6 S6 10 16.43 61.24 01.26 00:28 230 1
25 S5 S5 11 16.80 60.50 01.26 11:31 196 1
26 S4 S4 12 17.37 59.80 01.27 18:35 178 1
27 S3 S3 13 17.70 59.85 01.28 16:33 218 1
28 S2 S2 14 18.07 57.99 01.30 08:37 214 1
29 S1 S1 15 18.45 57.32 01.31 17:13 74 1
TN045 /
MOCNESS 1m
2
/
153 μm
7 N7 N7 2 19.26 67.05 03.18 11:37 299 8
7 N7 N7 3 19.25 67.16 03.18 20:56 299 8
13 S15 S15 5 10.08 64.77 03.24 18:11 295 8
17 S11 S11 6 14.49 64.93 03.26 11:29 295 5
17 S11 S11 7 14.60 64.99 03.26 22:14 199 6
21 S7 S7 10 16.06 61.83 03.30 12:21 296 8
21 S7 S7 11 15.99 62.00 03.31 22:57 200 6
26 S4 S4 12 17.30 59.82 04.02 12:00 299 8
26 S4 S4 13 17.25 59.77 04.03 17:50 1008 16
27 S3 S3 14 17.64 58.91 04.05 23:54 296 8
28 S2 S2 15 18.07 57.89 04.06 10:42 295 8
28 S2 S2 16 18.07 57.89 04.06 20:05 1244 15
TN045 /
BONGO /
153 μm
2 N2 N2 1 22.50 61.17 03.15 09:06 236 1
3 N3 N3 2 21.83 62.40 03.16 01:41 212 1
4 N4 N4 3 21.18 63.55 03.16 11:17 246 1
5 N5 N5 4 20.57 64.67 03.17 02:53 204 1
6 N6 N6 5 19.88 65.88 03.17 12:25 256 1
7 N7 N7 6 19.20 67.17 03.19 15:06 212 1
8 N8 N8 7 18.27 67.57 03.20 03:51 238 1
9 N9 N9 8 17.30 67.93 03.20 12:03 234 1
10 N10 N10 9 16.35 68.35 03.21 03:17 216 1
11 N11 N11 10 15.38 68.75 03.21 13:43 202 1
15 S13 S13 11 12.07 65.00 03.25 10:58 330 1
19 S9 S9 12 15.25 63.50 03.29 10:23 206 1
27 S3 S3 14 17.68 58.83 04.05 07:14 220 1
MB9503 /
MOCNESS 1m
2
/
153 μm
3 M3 05.00 49.08 05.04 17:49 1820 8
4 M4 05.68 49.41 05.05 11:20 1600 8
6 M6 08.43 51.07 05.06 18:26 1100 7
7 M7 10.20 52.03 05.08 10:18 1810 8
8 M7 10.18 52.04 05.08 17:47 1430 7
9 M7 10.01 52.14 05.09 11:07 1220 7
13 M13 14.53 59.81 05.12 18:06 1990 8
14 M14 15.53 61.45 05.13 16:56 100 7
18 M14 15.50 61.43 05.14 10:54 165 8
19 M14 15.58 61.51 05.14 15:43 162 7
20 M14 15.55 61.43 05.14 20:34 157 8
21 M14 15.49 61.46 05.15 01:13 99 8
22 M14 15.48 61.46 05.15 05:41 156 8
28 M28 18.91 58.21 05.19 12:12 1290 8
29 M28 18.91 58.19 05.19 18:37 1210 7
30 M30 22.00 59.93 05.20 22:18 1010 7
Halocyprid Ostracods of the Arabian Sea Region 11
Table 1 – continued
Cruise /
Net type /
Net mesh:
Station Standard
station
Station
symbol
in Fig.1
Tow
No
Latitude
(N)
Longitude
(E)
Date
(mm.dd)
Time
(start)
Depth
of tow
(m,
max)
Qty
of
sam-
ples
1995
MB9503 /
MOCNESS 1m
2
/
153 μm
31 M31 22.23 60.72 05.21 06:24 1300 8
32 M31 22.27 60.74 05.21 22:22 1300 8
33 M31 22.24 60.72 05.22 14:29 252 6
MB9506 /
MOCNESS 1m
2
/
153 μm
37 M37 23.17 59.74 07.31 22:33 1000 8
43 M43 18.72 58.00 08.05 10:36 990 8
45 M45 16.77 55.47 08.06 18:28 1250 8
46 M45 16.77 55.43 08.07 10:35 1240 8
48 M48 14.08 50.67 08.08 23:46 1200 8
49 M48 14.08 50.69 08.09 06:24 1140 8
54 M14 15.43 61.48 08.16 20:16 151 6
55 M14 15.44 61.48 08.17 03:55 149 7
57 M14 15.45 61.59 08.17 15:29 149 8
60 M14 15.44 61.54 08.18 09:47 148 8
62 S7 S7 16.00 61.99 08.19 05:55 1210 8
TN050 /
MOCNESS 1m
2
/
153 μm
3 N3 N3 1 21.76 62.37 08.20 08:26 397 8
7 N7 N7 2 19.09 67.12 08.23 13:00 294 8
7 N7 N7 3 19.02 67.12 08.23 21:00 300 8
13 S15 S15 4 09.89 64.80 08.28 12:03 298 8
13 S15 S15 5 09.90 64.80 08.29 21:35 300 8
21 S7 S7 8 15.87 61.89 09.04 12:39 290 8
24 S4 S4 10 17.16 59.76 09.07 12:25 296 8
TN050 /
MOCNESS
0.25 m
2
/
64 μm
7 N7 N7 32 19.18 67.21 08.23 05:19 200 8
7 N7 N7 33 19.11 67.23 08.23 16:53 200 8
13 S15 S15 34 09.98 64.89 08.28 15:41 200 8
13 S15 S15 35 09.95 64.89 08.29 04:25 200 8
17 S11 S11 36 14.40 64.99 09.01 04:19 200 8
17 S11 S11 37 14.44 65.00 09.01 15:53 200 8
21 S7 S7 38 16.01 61.99 09.04 16:27 200 8
21 S7 S7 39 15.95 61.96 09.05 04:19 200 8
24 S4 S4 40 17.19 59.76 09.07 16:22 200 8
24 S4 S4 41 17.15 59.76 09.08 03:25 200 8
26 S2 S2 42 18.08 58.04 09.10 15:28 200 7
26 S2 S2 43 18.10 58.07 09.11 03:14 200 8
TN050 /
BONGO /
153 μm
2 N2 N2 1 22.51 61.17 08.19 07:59 198 1
3 N3 N3 2 21.83 62.40 08.20 03:16 262 1
4 N4 N4 3 21.34 63.56 08.20 21:31 184 1
5 N5 N5 4 20.56 64.67 08.21 12:25 244 1
6 N6 N6 5 19.88 65.88 08.22 02:53 228 1
11 N11 N11 6 15.36 68.73 08.24 02:22 228 1
15 S13 S13 7 12.05 64.99 08.31 05:10 203 1
19 S9 S9 8 15.25 63.50 09.03 09:08 245 1
25 S3 S3 9 17.65 58.87 09.09 14:37 204 1
27 S1 S1 10 18.51 57.31 09.12 14:46 50 1
28 extra A 11 18.64 57.76 09.12 18:32 221 1
29 extra A 12 18.89 58.59 09.13 01:15 208 1
30 Arabesque A 13 19.01 59.03 09.13 06:35 205 1
31 extra A 14 20.39 59.07 09.13 18:04 248 1
12 Inna Drapun & Sharon L. Smith
Table 1 – continued
Cruise /
Net type /
Net mesh:
Station Standard
station
Station
symbol
in Fig.1
Tow
No
Latitude
(N)
Longitude
(E)
Date
(mm.dd)
Time
(start)
Depth
of tow
(m,
max)
Qty
of
sam-
ples
1995
TN054 /
MOCNESS 1m
2
/
153 μm
2 N2 N2 1 22.53 61.19 12.01 13:26 295 8
7 N7 N7 2 19.30 67.23 12.04 12:33 299 8
7 N7 N7 3 19.32 67.24 12.04 21:22 299 8
11 N11 N11 4 15.72 68.70 12.07 23:50 51 2
13 S15 S15 5 10.13 64.97 12.10 10:43 299 8
17 S11 S11 7 14.56 65.05 12.14 11:07 297 8
17 S11 S11 8 14.57 65.06 12.14 19:10 300 8
21 S7 S7 9 16.14 62.07 12.17 19:31 300 8
21 S7 S7 10 16.14 62.09 12.19 10:41 300 8
24 S4 S4 11 17.32 59.88 12.20 19:06 300 8
24 S4 S4 12 17.30 59.90 12.22 06:02 298 8
26 S2 S2 13 18.14 58.13 12.23 11:14 298 8
26 S2 S2 14 18.27 58.13 12.23 19:40 300 8
TN054 /
BONGO /
153 μm
1 N1 N1 1 22.40 59.90 11.30 17:49 157 1
2 N2 N2 2 22.51 61.17 12.01 05:36 221 1
4 N4 N4 3 21.19 63.52 12.02 16:47 208 1
6 N6 N6 4 19.90 65.88 12.03 21:30 155 1
9 N9 N9 5 17.31 67.93 12.06 20:37 199 1
11 N11 N11 6 15.39 68.77 12.08 09:59 200 1
15 S13 S13 7 12.08 65.00 12.13 00:16 212 1
19 S9 S9 8 15.27 63.50 12.16 20:36 179 1
25 S3 S3 9 17.68 58.82 12.22 17:46 239 1
27 extra A 10 17.79 57.78 12.25 07:23 203 1
30 S1 S1 11 18.49 57.31 12.26 02:26 89 1
0.25 m
2
-mouth area MOCNESS tows were 200–150, 150–100, 100–80, 80–60, 60–40, 40–20,
20–10 and 10–0 m. The target depth for all Bongo tows was 200 m.
In the GLOBEC cruises, zooplankton sampling was accomplished using a 1m
2
-mouth
area MOCNESS equipped with 153 μm mesh nets. Target depths on the cruises MB9503 and
MB9506 were 250-200, 200-150, 150–100, 100–80, 80–60, 60–60, 50–40, 40–20, 20–10, 10–0
m and 2000–1500, 1500–1250, 1500–1000, 1250–1000, 1000–750, 1000–500, 750–500, 500–
300, 300–150, 150–100, 100–50, 50–0 m.
All plankton collections were preserved in a 4% buffered formaldehyde-seawater solution.
Laboratory analysis
The samples were split one to six times, depending on the amount of plankton present,
using a Folsom Plankton Sample Splitter at the Rosenstiel School of Marine and Atmospheric
Science (RSMAS) in Miami, Florida, USA.
Taxonomic analyses of the samples were made at the Institute of Biology of the Southern
Seas (IBSS) of the National Academy of Sciences of Ukraine in Sevastopol. A total of 889
samples have been analyzed (Table 1). For calculation of abundance of the species, in most
samples, all the specimens of ostracods, adults and juveniles, were identi ed and counted. In
some samples, only the organisms larger than 1.0–1.5 mm were taken into account in a whole
sample; smaller sized individuals were counted in a smaller subsample (most often in 1/5 (20
ml), sometimes in 1/10 (10 ml), part of a sample diluted up to 100 ml) collected by a 5 ml
Stempel pipette. Identi cations were performed with the aid of Leningrad Optics-Mechanics
Company (LOMO) MBR-9 stereomicroscopes using different magni cations depending on the
sizes of the individuals being identi ed.
Halocyprid Ostracods of the Arabian Sea Region 13
For anatomical examination, the formalin- xed specimens of the adult females and
males were immersed in a 50:50 solution of glycerine and distilled water on glass slides, then
measured and dissected. All these operations were made with the use of a LOMO MBR-9
stereomicroscope.
All line drawings were made from glycerine-mounted specimens using a camera lucida
on a Leica DM LS2 compound microscope. In the illustrations, some minor details, such as
hair and spinules that are not referred to in the species descriptions, are often omitted, and
some structures, such as long setae, that are dif cult to show in their entirety are only partly
illustrated.
Photographs were made with a Canon PowerShot A520 camera. Most halocyprid ostracods
have delicate, transparent carapaces and a dark body inside. The specimens of some species
were stained by a solution of 1% chlorazol black E (SBE) dissolved in 70% ethanol to provide
a better image of the carapace margins.
Taxonomic identi cation of the halocyprid species is based mainly on the following
taxonomic papers and monographs: Angel (1969a, b; 1970; 1971; 1981; 1982; 1999), Chavtur
& Angel (2011), Chavtur & Stovbun (2003; 2008a, b), Deevey (1968a; 1970; 1974; 1978;
1982), Deevey & Brooks (1980), Ellis (1984), George (1979), Gooday (1981), Kock (1992),
Martens (1979), Müller (1906), Poulsen (1969b; 1973), Skogsberg (1920).
Data analysis: Maps and diagrams
The maps demonstrating horizontal occurrence of every described species are based on
the data of all the samples that have been analysed (i.e., 889 samples).
The diagrams showing vertical occurrence of every described species are based on the
data of all the strati ed tows (110 tows, excluding Bongo sampling; see Table 1). Since target
sampling depths varied in the different cruises, the following layers, more or less appropriate
to standard ones, were used in the diagrams: see Table 2. In the second column of the table, the
numbers of tows through the corresponding layers during the investigation period are presented.
For example, the layer 50–100 m was sampled in all 110 tows listed in Table 1. Each diagram
shows the vertical distribution of the number of records of a species as a percentage of the
total number of tows in the corresponding layers. The deeper layers were less sampled, and the
corresponding data were less representative than from the upper layers.
Table 2. The total numbers of tows in the corresponding layers used in the analysis of vertical occurrence of the
described species.
Layer, m Number of tows in the corresponding layer
0–50
107
50–100
110
100–150
106
150–200
99
200–250
85
250–300
83
300–500
43
500–750
32
750–1000
32
1000–1250
19
1250–1500
13
14 Inna Drapun & Sharon L. Smith
MORPHOLOGY OF THE HALOCYPRID OSTRACODS
The most detailed description of the morphology and functions of the appendages of
halocyprid ostracods can be taken from Skogsberg (1920), Iles (1961), Angel (1999), and
also the web-Atlas of Atlantic Planktonic Ostracods (Angel et al., 2008). In the present book,
the brief description of the morphology and the main taxonomic characters of the ostracods
belonging to the family Halocyprididae are based heavily on these sources in addition to our
own observations of large number of individuals from collections made in the Arabian Sea
Region in the 1990s (Table 3). Also, the new notions of morphology of the fth and sixth limbs
are used in the descriptions of these appendages (Kornicker, 2003).
The members of the subfamily Conchoeciinae, having the largest number of species, are
represented here as the example of halocyprid morphology.
The ostracod body is entirely inside a bivalve carapace (Figs 2, 3). The dorsal margins of
both carapace valves are joined, and this hinged part of the margin is straight. This is one of the
main distinctive characters of the family. Anteriorly, the carapace is developed into the rostrum.
The shapes of carapaces, the absence or presence of the varying spines, tubercles and sculptures
on the carapace surface are important features used in de ning the species and genera of the
halocyprids.
Fig. 2. Carapace of a halocyprid ostracod. A – both valves outside; B – ventral.
RAG right asymmetrical gland; LAG left asymmetrical gland; LGG group of lateral glands; MGG group
of male glands. Modi ed from Angel (1999).
Along the free margins of the carapace there are many glandular cells. Some of them are
united in more or less large groups (Fig. 2). First of all, in the Conchoeciinae there are two groups
of glands located on each carapace valve asymmetrically, the left and right asymmetrical
glands (LAG and RAG). In the Euconchoeciinae and Archiconchoeciinae these glands are
Halocyprid Ostracods of the Arabian Sea Region 15
placed symmetrically (Euconchoecia: Pl. 79C) or almost symmetrically (Archiconchoecia:
Pl. 1D) on both valves but the names “LAG” and “RAG” are used in these cases too. The
main feature of these compound glands is that all their glandular cells have a common pore
(opening). All ostracods of the family Halocyprididae have LAG and RAG, and locations of
these glands are very important taxonomic characters. In most species the left asymmetrical
gland opens on the dorsal margin of the left carapace valve near the posterior dorsal corner. In
some species it is more or less moved forward along the dorsal margin, and can open even on
the rostrum (Nasoecia: Pl. 77D). The usual position of the right asymmetrical gland is nearly to
the posterior ventral corner of the right carapace valve, but in some cases it is moved forward
along the ventral margin and can open even on the anterior margin below the rostral incisure
(Conchoecilla: Pls 3A, 20A).
In addition to the LAG and RAG there are other groups of glands, the lateral gland groups
(LGG) and the male gland groups or medial-dorsal glands (MGG). These groups of glands have
essential distinctions from the asymmetrical glands. Each glandular cell in an LGG or MGG group
has a single opening located close to others. Also, LGG and MGG are usually placed symmetrically
on each carapace valve. In the tribe Conchoeciini of subfamily Conchoeciinae, all males have MGGs
which are always located on the posterior margins of valves just below posterior dorsal corners.
LGGs are usually opening either on the posterior margins of the carapace below the posterior dorsal
corners or near the posterior ventral corners. The right ventral LGG is placed either on the posterior
margin just above the RAG or just over RAG (as in Fig. 2). Some species have both dorsal and
ventral LGGs. The locations of the different kinds of glands are important taxonomic characters.
The ostracod body has an unpaired frontal organ, seven paired appendages, and an unpaired
copulatory appendage in males. The body ends in the caudal furca. In contrast to myodocopids
the eyes are always absent on the body of halocyprid, and this is one more important distinctive
feature of the family.The arrangement of the appendages within the carapace of the adult
halocyprid ostracod is shown in Fig. 3.
The frontal organ (FO) (Figs 3, 4) is an unpaired appendage that is placed between the
right and left antennules. In most cases, the frontal organ is sexually dimorphic. Usually it has
two parts, stem and capitulum; in some species (usually in females) FO with no clear division
on stem and capitulum (for example, as in Discoconchoecia discophora in Pl. 24D).
The rst antennae or antennules (An1) (Figs 3, 4) are uniramous and sexually dimorphic.
Two terminal segments bear long setae. The number of setae is varied in different subfamilies.
In species of the subfamily Conchoeciinae, there are ve terminal setae. Some of them are thin-
walled and always bare, and named “sensory setae”. The female has four sensory setae (a- to d-
setae), the male only two (a- and c- setae). Other setae may carry different spines, hairs or teeth,
or none of these. The lengths and armature of setae are important in the taxonomic analysis.
The second segment of rst antenna has, always in males and often in females, a dorsal seta. In
males this seta is hook-like and turned around the frontal organ.
The second antennae or antennae (An2) (Figs 3, 5) are biramous. Each antenna has
a very large protopodite (usually larger in males) with powerful muscles that provide the
basic function of the second antennae, swimming. The exopodite has one elongated segment
and eight short segments (Fig. 5B); each short segment has a long plumose swimming seta;
the terminal exopodite segment usually has two additional shorter setae. The endopodite is
placed on the inner side of the protopodite disto-ventrally (Fig. 5A); it is strongly sexually
dimorphic. In the Conchoeciinae the basal segment of the endopodite usually is similar
in both sexes: attened, broad, and with two processes on the anterior side. The distal
process bears two relatively short setae (a- and b- setae). The proximal one, so named
“processus mamillaris”, has a conical shape and no setae. In the males the endopodite is
16 Inna Drapun & Sharon L. Smith
Fig. 3. Arrangement of the appendages within the carapace of the adult halocyprid ostracod. A – female
without right valve of carapace; B – posterior part of the male body.
FO frontal organ; An1 rst antenna; An2 second antenna; Lb labrum; Md mandible; Mx maxilla;
P5 fth limb; P6 sixth limb; P7 seventh limb; CF caudal furca; CA copulatory appendage.
three-segmented (Fig. 5C). The second segment is furnished with ve setae: c- and d- setae
are usually rather short (sometimes one of them is far longer than other, as in Fig. 5C),
e-seta is extremely short, f- and g- setae are the longest. The third segment usually with
a hook-like appendage named “hook appendage” or “clasping organ” (“clasper”). Right
hook appendage is usually larger than left. There are three setae (h- to j-) near the base of
hook appendage which are always shorter than f- and g- setae. In the females these three
setae represent the third segment that is fused with the second (Fig. 5A: Enp2+3); c- and
d- setae are usually absent (except in rare cases); e-seta is always absent; f- and g- setae
are usually relatively shorter than in the males.
The labrum or upper lip (Lb) (Figs 3, 6) is located in front of the mouth between the
antennal protopodites. The posterior edge of the hyaline membrane is useful in de ning the
species and genera. Also, our observations show that the outline of the labrum’s dorsal projection
(Fig. 6A) can be used as one of the distinctive characters of a species or genus.
The mandibles (Md) (Figs 3, 7A, B) demonstrate slight sexual dimorphism. In the
male, the basis of the mandible is usually more elongated than in the female. Also, the
dorsal seta on the rst segment of the male’s endopodite is often plumose, but in the female
it is non-plumose. The protopodite of the mandible has well-developed coxal and basal
segments; ventrally the coxa and the basis form the endites with toothed edges. Besides the
toothed edge, the coxal endite has two toothed plates, named “distal and proximal tooth-
lists”, and a masticatory pad. All these structures are used in the grinding of food items.
Poulsen (1973) has used these in taxonomic analyses, but in many species they are dif cult
to distinguish due to their extremely small size. In this book these structures were not
used in the descriptions of species, while there are drawings of these in some species (for
example, in Pls 8I, 10J). The mandible’s exopodite usually is reduced to a small peg with
a long plumose seta. The endopodite is well developed. Its rst segment carries from one
to four ventral setae, and the numbers and lengths of these setae are important taxonomic
characters. Also, the relative length of the longest terminal seta is a useful taxonomic feature.
Halocyprid Ostracods of the Arabian Sea Region 17
Fig. 4. Limbs of the halocyprid ostracods: frontal organ (FO) and right rst antenna (An1). A – female;
B – male. ae nomenclature of setae.
Fig. 5. Limbs of the halocyprid ostracods: second antenna. A – female, left An2 inside; B – distal part of Exp;
C – male, right Enp.
Prp protopodite; Exp exopodite; Enp1–3 segments of endopodite; Enp2+3 – fused 2
nd
and 3
rd
segments of
endopodite; aj nomenclature of setae.
Fig. 6. Labrum. A – dorsal projection; B – lateral projection.
18 Inna Drapun & Sharon L. Smith
The maxillae (Mx) (Figs 3, 7C) are uniramous, not sexually dimorphic, and only slightly
variable among the different genera. The endopodite has only two segments. Main taxonomic
characters are: the number of setae on anterior side of the rst segment, a seta on maxilla’s basis
and its armature, the spines near distal edge of rst endopodite segment.
Fig. 7. Limbs of the halocyprid ostracods. A left mandible inside; B – coxal endite (higher magni cation).
C left maxilla inside.
Cxp – coxa; Bsp – basis.
The fth limbs (P5) (Figs 3, 8A) show a little sexual dimorphism. The exopodite is
represented by a single, long, usually non-plumose seta (Kornicker, 2003). The endopodite
two-segmented. The following main characters are useful in de ning the species and genera:
number of setae in proximal and distal groups on the ventral side of the basis; the relative
lengths of endopodite terminal setae; the number of setae which are located more or less close
to the end of slightly prolonged antero-ventrally part of third coxal endite (ventral group of
setae, Fig. 8A). The fth limb has an epipodite with three groups of setae: usually the proximal
group has four long plumose setae, the medial group has ve setae, and the distal group has four
long setae and one additional short non-plumose seta. But in some cases the number of setae in
groups can be different (for example, in Fig. 8A medial group has six setae).
The sixth limbs (P6) (Figs 3, 8B, C) are strongly sexually dimorphic in the
Conchoeciinae. The endopodite is three-segmented in both sexes. The basis is smaller in
female, and usually has ve ventral setae, a dorso-lateral seta and a dorsal (disto-dorsal)
seta. The latter is a vestige of exopodite (Kornicker, 2003). All these setae and setae on
the rst and second endopodite segments are often reduced in males. On the contrary
the male terminal segment has very long setae that protrude beyond the posterior margin
of the carapace, usually near the male gland groups. These setae are usually plumose,
but in some cases one of them is thinner and without long hairs (as in Conchoecissa
plinthina in Pl. 23R). The female has three relatively short, claw-like terminal setae.
The sixth limb has epipodite with three groups of setae, as in the fth pair of limbs,
but these groups usually have ve, ve and six long plumose setae in the each group.
Halocyprid Ostracods of the Arabian Sea Region 19
Fig. 8. Limbs of the halocyprid ostracods. A – left fth limb inside. Left sixth limbs inside: B female;
C – male. D seventh limb.
The seventh limbs (P7) (Figs 3, 8D) are strongly reduced, having two or three segments.
The terminal segment usually bears two setae in which one is longer than the other.
The caudal furca (CF) (Fig. 3) of adult specimens consists of two plates each with 6–8
claws (always eight claws in the Conchoeciinae). In many species, behind the claws there is an
unpaired dorsal seta. The number of claws is usually the distinctive character of the juvenile
instars. A new pair of claws is added at each instar.
The main distinctive character of the adult males is the presence of a copulatory
appendage (CA) (Fig. 3B). It is an unpaired attened structure which is located near the base
of the caudal furca on the left side of ostracod’s body. In the males of all species described in
this book, the copulatory aappendages are always viewed from their left side, as in Fig. 3B.
20 Inna Drapun & Sharon L. Smith
ABBREVIATIONS
used in the descriptions, gures and keys
L – carapace length
H – carapace height
H
ant
– height of anterior half of carapace
H
post
– height of posterior half of carapace
LAG – left asymmetrical gland
RAG – right asymmetrical gland
MGG – group of male (medial-dorsal) glands
LGG – group of lateral glands
PDC – posterior dorsal corner of carapace
PVC – posterior ventral corner of carapace
FO – frontal organ
An1 rst antenna (antennula)
An2 – second antenna (antenna)
Lb – labrum (upper lip)
Md – mandible
Mx – maxilla
P5 fth limb
P6 – sixth limb
P7 – seventh limb
CA – copulatory appendage
CF – caudal furca
Prp – protopodite
Cxp – coxa (coxale, coxopodite); Cxp1–3 – coxal endites
Bsp – basis (basale, basipodite)
Exp – exopodite
Enp – endopodite; Enp1–3 – segments of endopodite
N – number of individuals
Halocyprid Ostracods of the Arabian Sea Region 21
SYSTEMATIC ACCOUNT
11
Kingdom
Animalia
Philum
Arthropoda
Subphilum Crustacea Brünnich, 1772
Class Ostracoda Latreille, 1802
Subclass Myodocopa Sars, 1866
Order Halocyprida Dana, 1853
Suborder Halocypridina Dana, 1853
Superfamily
Halocypridoidea Dana, 1853
Family Halocyprididae Dana, 1853
Table 3. Total list of halocyprid species identi ed in the investigated region with their size and abundance
characteristics.
Taxon
L (mm) N (ind.)
females males females males juveniles
Subfamily Archiconchoeciinae Poulsen, 1969
Archiconchoecetta bispicula (Deevey, 1978)
0.94–0.97 0.80 2 3 16
Archiconchoecia (A.) striata Müller, 1894*
0.50–0.59 0.52–0.64 8033 5354 24350
Archiconchoecinna cuneata (Müller, 1908)
0.80 0 1 0
Archiconchoecissa cucullata (Brady, 1902)
1.75–1.98 1.60–2.08 14 9 104
Subfamily Conchoeciinae Müller, 1912
Tribe Conchoeciini Chavtur & Angel, 2011
Alacia alata (Müller, 1906) *
2.01–2.36 1.73–2.08 80 104 822
Alacia leptothrix (Müller, 1906) *
3.30–3.35 20 0
Conchoecetta acuminata Claus, 1890 *
2.74–2.91 2.08 2 1 13
Conchoecetta giesbrechti (Müller, 1906) *
1.77–2.45 1.58–2.05 1085 1377 11679
Conchoecia lophura Müller, 1906 *
2.55–2.72 2.08–2.45 14 12 191
Conchoecia macrocheira Müller, 1906 *
3.10 0 1 7
Conchoecia magna Claus, 1874 *
1.56–1.87 1.46–1.65 407 470 5244
Conchoecilla daphnoides Claus, 1890 *
3.30–3.77 2.22–2.36 5 10 35
Conchoecissa imbricata (Brady, 1880) *
2.78–3.02 2.55–2.64 2 3 32
Conchoecissa plinthina (Müller, 1906) *
5.28 4.53–4.83 1 2 8
Conchoecissa symmetrica (Müller, 1906)
3.68 10 5
Discoconchoecia discophora (Müller, 1906) *
1.23–1.42 1.08–1.23 443 290 1588
Discoconchoecia aff. elegans (Sars, 1865) *
1.18–1.37 1.22–1.28 22 14 94
Discoconchoecia tamensis (Poulsen, 1973) *
0.97–1.18 1.04–1.18 2725 1355 15200
Loricoecia loricata (Claus, 1894) *
1.60–1.84 1.46–1.60 18 15 45
Macroconchoecia caudata (Müller, 1891) **
2.91(5.65***) 0 1 8
Mikroconchoecia curta s.l. (Lubbock, 1860) *
0.75–0.94 0.71–0.92 188 249 2129
Mikroconchoecia stigmatica (Müller, 1906) *
0.94–1.04 1.07–1.13 7 7 9
Mollicia acanthophora (Müller, 1906) **
2.97–3.16 2.88 3 1 0
Mollicia mollis (Müller, 1906)
3.16–3.21 2.59–2.92 2 3 3
Orthoconchoecia atlantica (Lubbock, 1856) *
3.07–3.73 3.07–3.54 112 134 834
Orthoconchoecia bispinosa (Claus, 1890)
1.84–2.08 1.65 3 1 10
Orthoconchoecia secernenda (Vavra, 1906)
2.26–2.31 30
406
Orthoconchoecia striola s.s. (Müller, 1906) *
2.12–2.48 1.98–2.26 32 50
1
Classification from WoRMS (http://www.marinespecies.org/aphia.php?p=taxdetails&id=2) (high taxa)
and (Angel et al., 2008).
22 Inna Drapun & Sharon L. Smith
Table 3 – continued
Taxon
L (mm) N (ind.)
females males females males juveniles
Paraconchoecia allotherium (Müller, 1906) *
1.51–1.70 1.42–1.51 19 21 ****
Paraconchoecia cophopyga (Müller, 1906) **
3.10 0 1 0
Paraconchoecia echinata (Müller, 1906) *
1.89–2.06 1.65–1.79 17 14 42
Paraconchoecia inermis Claus, 1890 *
1.96–2.15 1.87–2.03 6 2 5
Paraconchoecia mamillata (Müller, 1906) **
1.60–1.79 1.42–1.58 16 10 45
Paraconchoecia oblonga Claus, 1890, form A *
1.51–1.77 1.32–1.44 16 26
120
Paraconchoecia oblonga Claus, 1890, form B *
1.65–1.75 1.42–1.51 6 9
Paraconchoecia spinifera Claus, 1890 **
1.89–2.03 1.92 5 1 33
Paramollicia dichotoma (Müller, 1906) *
2.17–2.45 1.84–1.93 11 7 15
Platyconchoecia prosadene (Müller, 1906) *
2.36–2.78 2.06–2.29 12 56 505
Porroecia parthenoda (Müller, 1906) *
1.54–1.77 1.42–1.60 56 31 350
Porroecia porrecta (Claus, 1890) *
1.23–1.51 1.13–1.32 2469 2247 13400
Porroecia spinirostris (Claus, 1874) *
1.07–1.23 0.92–1.07 109 71 420
Proceroecia brachyaskos (Müller, 1906) *
1.23–1.32 1.08–1.16 16 23 34
Proceroecia brachyaskos (Müller, 1906), deep form
1.46–1.56 1.27 3 1 4
Proceroecia decipiens (Müller, 1906) *
1.32–1.58 1.13–1.30 462 442 3459
Proceroecia macroprocera (Angel, 1971) *
1.23–1.35 1.11–1.23 166 195
51100
Proceroecia microprocera (Angel, 1971) *
0.90–1.08 0.83–0.97 13800 9100
Proceroecia procera (Müller, 1894) *
1.10–1.21 0.99–1.08 106 75
Pseudoconchoecia concentrica (Müller, 1906) *
1.23–1.51 1.18–1.46 314 223 2124
Tribe Metaconchoeciini Chavtur & Angel, 2011
Clausoecia pusilla (Müller, 1906) *
0.75–0.96 0.71–0.87 324 205 1039
Kyrtoecia kyrtophora (Müller, 1906) *
0.78–0.85 0.74–0.83 61 59 140
Metaconchoecia spp. 1+2 **
0.94–1.18 0.94–1.18 1734 1236 4760
Metaconchoecia sp. 3 **
0.81–0.92 0.80–0.92 1596 1172 4750
Muelleroecia macromma (Müller, 1906)
0.94 10 2
Muelleroecia sp. 1 **
0.94–1.04 0.88–0.99 78 67 154
Muelleroecia sp. 2 **
1.27–1.35 1.23–1.27 5 2 7
Nasoecia nasotuberculata (Müller, 1906) *
0.80–0.90 0.75–0.85 41 25 161
Subfamily Euconchoeciinae Poulsen, 1969
Bathyconchoecia sp. (L 0.75–0.85 mm)
−− 00 2
Euconchoecia cf. aculeata (Scott, 1894) *
0.85–1.08 0.85–0.99 5158 2604
71660
Euconchoecia aff. aculeata elongata Müller, 1906 *
1.11–1.60 1.02–1.30 7946 5158
Euconchoecia cf. chierchiae Müller, 1891 *
1.23–1.51 1.23–1.35 21 10 183
Subfamily Halocypridinae Claus, 1890
Fellia bicornis (Müller, 1906) **
1.91 10 4
Fellia cornuta (Müller, 1906)
3.02 10 0
Halocypris in ata (Dana, 1849) **
1.42–1.70 1.27–1.49 27 60
417
Halocypris pelagica Claus, 1890 **
1.23–1.35 1.08–1.18 4 11
Halocypria globosa Claus, 1874 **
2.22 1.75–1.84 1 2 35
* species described and illustrated in this book;
** species in which only the carapace outlines are presented herein;
*** L with rostral and dorsal spines;
****
juveniles of P. allotherium were considered together with those of P. oblonga.
Halocyprid Ostracods of the Arabian Sea Region 23
Family Halocyprididae Dana, 1853
The family Halocyprididae is divided into ve subfamilies (Angel, 1999). The members
of four subfamilies have been found in the investigated material: Archiconchoeciinae Poulsen,
1969; Conchoeciinae Müller, 1912; Euconchoeciinae Poulsen, 1969 and Halocypridinae Claus,
1890 (Table 3, Appendices 1, 2).
Key to the four subfamilies of Halocyprididae *:
1 Terminal segments of An1 with 6 and more setae …….....…........................................………. 2
1a Terminal segments of An1 with 5 setae …………....…..……….….……..............…………… 3
2 Terminal segments of An1 with 6 setae ( as in Pl. 1E).……..……...........… Archiconchoeciinae
2a Terminal segments of An1 with 20–30 (as in Pl. 79E)
or more than 100 sensory and other setae ........................................................ Euconchoeciinae
3a
FO and An1 exhibit sexual dimorphism (Fig. 4); An2 Enp1 with
a tubercle (processus mamillaris) on its anterior margin (Fig. 5) ……………… Conchoeciinae
3
FO and An1 are similar in both sexes;
An2 Enp1 without processus mamillaris ……………...………………....….… Halocypridinae
Subfamily Archiconchoeciinae Poulsen, 1969
After the revision made by Chavtur & Stovbun (2003) the subfamily Archiconchoeciinae,
which earlier than 2003 was monogenetic, has been divided into seven genera and two
subgenera.
The members of four genera have been found in the analyzed material: Archiconchoecetta
Chavtur & Stovbun, 2003; Archiconchoecia Müller, 1894; Archiconchoecinna Chavtur &
Stovbun, 2003 and Archiconchoecissa Chavtur & Stovbun, 2003 (Table 3, Appendices 1, 2).
Only one of these genera, Archiconchoecia, is represented herein. For descriptions of the
remaining genera and also their members listed in Table 3, see Chavtur & Stovbun (2003) and
Deevey (1968a, 1978).
Genus Archiconchoecia Müller, 1894
Small species (0.50–0.85 mm) with carapaces having characteristic shape: posterior and
ventral margins strongly arched especially in females; there is a distinct notch on each of the
valves mid-dorsally. RAG and LAG placed on the upper half of the posterior margin (Chavtur &
Stovbun, 2003).
Subgenus Archiconchoecia (Archiconchoecia) Chavtur & Stovbun, 2003
Carapace less than 0.7 mm, rostrum small, rostra incisure absent, hook appendages on the
male An2 with pointed tips (Chavtur & Stovbun, 2003).
Only A. (A.) striata Müller, 1894 has been found in the analyzed material (Table 3,
Appendix 2).
Herein and in all remaining keys, the underlined words refer to the halocyprid body parts whose characters are used in the
identi cation of taxa.
a
24 Inna Drapun & Sharon L. Smith
Archiconchoecia (Archiconchoecia) striata Müller, 1894
(Pict. 1; Pls 1, 2; Figs 9, 10)
For synonymy before 1906, see Müller, 1906a.
Archiconchoecia striata: Müller, 1906a, p. 45, pl. VII gs 13–17; Deevey, 1968a, p. 23, g 4; George, 1979,
p. 123, gs 1–15; Martens, 1979, p. 309, g. 4; Angel, 1999, pp. 819, 836, g. 9.15.
Archiconchoecia (Archiconchoecia) striata: Chavtur & Stovbun, 2003, p. 145, 156.
Pict. 1. Archiconchoecia (Archiconchoecia) striata. A – female; B – male.
Females. L = 0.50–0.59 mm (0.55 ± 0.01 mm; N = 460); H/L = 67.5 ± 2.4% (N = 20).
Plate 1AN. Carapace (AD): posterior and ventral margins strongly arched; there is
a distinct notch on each of valves mid-dorsally; rostrum short; both asymmetrical glands open
on posterior margin: RAG at approximately 1/3 of H from dorsal margin, LAG somewhat
closer to PDC; surface of carapace with concentric striation and covered with rare hairs.
FO (E, F): short; undifferentiated on stem and capitulum; its tip usually rounded, with tiny papilla.
An1 (E): 6-segmented (George, 1979; Chavtur & Stovbun, 2003) but no clear differentiation between
2
nd
and 3
rd
segments in Arabian Sea specimens; 2
nd
segment has long, spinose dorsal seta, and
ventrally a row of long hairs directed distally; two terminal segments bear 6 equall in lenght sensory
setae with pointed tips and without any spines. An2 (GI): inner surface of Prp bare; Exp1 with
tiny hairs on its anterior side; long seta on Exp2 about 1.5 times longer than Prp; End1 with distinct
short spines on its posterior side, and with curved, rather long a- and b- setae; typical processus
mamillaris absent but in its place there is a small swelling; all setae on Enp2+3 about equal.
Lb (J): dorsal projection almost round with 2 rounded processes anteriorly; hyaline membrane
with almost straight edge. Md (K): Bsp shortened; Exp not developed, in its place usually there
are 2 plumose setae, sometimes 1 (or 1 seta on right Md and 2 setae on left one); Enp1 has
non-plumose dorsal seta and 2 ventral setae. Mx (as in male in Pl. 2K): Bsp with a short single
seta furnished with a few long hairs near its base; Enp1 has 6 setae on anterior side (5 of them
plumose), 3 setae on posterior side (one of them plumose), 1 laterally, and long hairs near distal
edge; Enp2 with 5 setae and long hairs disto-ventrally. P5 (L): Cxp3 with 6 setae (one of them
plumose, placed a little away from others) in ventral group; Bsp with 4 setae in proximal ventral
group (one of them plumose), 1 seta in distal ventral group, 1 plumose dorso-lateral and 1 dorsal
(vestige of Exp) extending beyond the end of limb; Enp1 has long dorsal seta, 2 short ventral and
a few long hairs proximo-ventrally. P6 (M): Cxp2 bears 1 long plumose seta and 1 extremely short
seta; Bsp has 3 ventral setae, 1 dorso-lateral (all setae plumose), and a few long hairs proximo-
ventrally; dorsal seta (vestige of Exp) on Bsp missing; Enp2 with very long dorsal seta. P7 (as
in male in Pl. 2N): with 2 rather short terminal setae. CF (N): has 6 long weak claws; unpaired
dorsal seta present.
Males. L = 0.52–0.64 mm (0.58 ± 0.02 mm; N = 370); H/L = 58.5 ± 1.9% (N = 21).
Plate 2AO. Carapace (AC): more elongated than in female; ventral margin less arched;
MGGs absent. FO (D): similar to that in female but longer, with rounded tip. An1 (D): as in
Halocyprid Ostracods of the Arabian Sea Region 25
female but relatively larger. An2 (EG): rather long c- and d- setae present; e-seta missing;
g-seta only slightly longer than other setae; both hook appendages strongly curved, tapered
distally; their lengths about equal; right appendage with distinct swelling in its mid-part.
Lb (H): in dorsal projection more elongated than in female. Md (I, J): Bsp more elongated than
in female; Enp1 with 4 ventral setae. Mx (K), P5 (L), P6 (M), P7 (N), CF: similar to those in
female. CA (O): attened and large; with widened mid-part; strongly narrowed distally.
Remarks. Chavtur & Stovbun (2003) divided the genus Archiconchoecia into two
subgenera. Arabian Sea specimens belong to the subgenera A. (Archiconchoecia), and closer to
A. (A.) striata Müller, 1894 (Chavtur & Stovbun, 2003: p. 145), but differ from it by missing
lens-like structure near ventral margin.
Distribution. Archiconchoecia (Archiconchoecia) striata is recorded generally from
The Atlantic and Indian oceans (42°S–45°N); shallow mesopelagic species (Angel et al., 2008).
In the investigated area, A. (A.) striata was found at all stations (Fig. 9), in all tows except one.
It was one of the most abundant species (Table 3). Maximum abundances were recorded at
depths 50–150 m (Fig. 10).
Fig. 9. Occurrence of Archiconchoecia (Archiconchoecia) striata
at the stations listed in Table 1. Circles represent stations sampled,
closed circles represent stations where adults and juveniles of the
species were found.
Fig. 10. Occurrence of Archiconchoecia (Archiconchoecia) striata
at different depths. X-axis represents the number of records of the
species as a percentage of the total number of tows (Table 2) in the
corresponding layers.
0
100
200
300
400
500
600
700
800
900
1000
1100
1200
1300
1400
1500
020406080
%
Depth, m
0
100
200
300
400
500
600
700
800
900
1000
1100
1200
1300
1400
1500
020406080
%
Depth, m
26 Inna Drapun & Sharon L. Smith
Plate 1. Archiconchoecia (Archiconchoecia) striata, female. Carapace: A – lateral; B – ventro-lateral; C – ventral;
D – both valves outside. E – FO and An1. F – other specimen: capitulum of FO. An2: G – Prp and Exp; H – left
Enp inside; I – right Enp outside. J – Lb. K – Md without Cxp. L – P5. M – P6. N – CF.
Halocyprid Ostracods of the Arabian Sea Region 27
Plate 2. Archiconchoecia (Archiconchoecia) striata, male. Carapace: A – lateral; B – ventral; C – both valves
outside. D – FO and An1. An2: E – Prp and Exp; F, G – left and right Enps. H – Lb. Md: I – Bsp, Exp and Enp;
J – other specimen: Exp. K – Mx. L – P5. M – P6. N – P7. O – CA.
28 Inna Drapun & Sharon L. Smith
Subfamily Сonchoeciinae Müller, 1912
After the revision made by Chavtur & Angel (2011) the subfamily Conchoeciinae has
been divided into two tribes: Conchoeciini and Metaconchoeciini.
Key to the tribes of Conchoeciinae:
1 LAG is located in posterior part of carapace, more or less close to PDC;
RAG usually more or less close to PVC, sometimes strongly moved anteriorly,
in one genus (Conchoecilla) on anterior margin; MGGs present;
Mx Enp1 with 5–6 setae on anterior side …………...……………..……..…......... Conchoeciini
1a
LAG opens on the anterior third of dorsal margin or on rostrum;
RAG more or less close to PDC; MGGs absent;
Mx Enp1 with 4 anterior setae …………...…………………………..…....... Metaconchoeciini
Tribe Conchoeciini Chavtur & Angel, 2011
The species of the following 17 genera of the tribe Conchoeciini have been found in the
investigated material: Alacia Poulsen, 1973; Conchoecetta Claus, 1890; Conchoecia Dana, 1849;
Conchoecilla Claus, 1890; Conchoecissa Claus, 1890; Discoconchoecia Martens, 1979; Loricoecia
Poulsen, 1973; Macroconchoecia Granata & Caporiacco, 1949; Mikroconchoecia Claus, 1890;
Mollicia Poulsen, 1973; Orthoconchoecia Granata & Caporiacco, 1949; Paraconchoecia Claus,
1890; Paramollicia Poulsen, 1973; Platyconchoecia Poulsen, 1973; Porroecia Martens, 1979;
Proceroecia Kock, 1992; Pseudoconchoecia Claus, 1890 (Table 3, Plates 3–7, Appendices 1, 2).
The key to all genera of the tribe Conchoeciini identi ed in the investigated material is
below. This key is based mainly on the features of species (the members of Conchoeciini genera)
that are described in this book, primarily on characteristics of their carapaces. The members of
genera Macroconchoecia and Mollicia are not described in detail here but there are the drawings
of their carapaces.
Key to the genera of Сonchoeciini:
1 RAG is located on anterior margin of carapace (Pl. 3A) ………...…………...…. Conchoecilla
Other features. LAG opens on posterior margin below PDC; PDCs strongly extended
(right longer than left) and pointed; carapace surface diagonally striated. (Pl. 20A, C).
1a RAG is located in posterior part of carapace ………………………….….…..……….………. 2
2
Both PVCs with more or less developed tubercles; RAG opens at apex
of right tubercle (Pl. 3B) …………………………………………………...…….. Conchoecissa
Other features. Rostrum elongated, pointed; PDCs of both valves with distinct spines
(left longer than right); posterior and dorsal margins of carapace form acute angle; carapace
surface strongly reticulate.
2a Both PVCs without tubercles ……………………………………….…………....……….……. 3
3 Carapace with striking sculpture mainly of rows of squares or rectangles;
in some species with spines like those of M. caudata (Ellis, 1984)
(Pl. 3C) …………………………….…....………………………………….... Macroconchoecia
3a
Carapace with another sculpture or without it ……………………………………………...….. 4
Halocyprid Ostracods of the Arabian Sea Region 29
4 Posterior margins of carapace with LGGs near PVCs ..........................…………………..…….. 5
4a
Posterior margins of carapace without LGGs near PVCs
...…...……….…...........................…10
5 Each carapace valve with 2 LGGs near PVC (just above RAG on right valve)
(Pl. 4A ) ..……...…………………………………………………….……..…………...…. Alacia
5a Each carapace valve with 1 LGG near PVC ……….…………………….………..…..……....... 6
6 RAG strongly moved anteriorly (Pl. 4B) ……………..…….………………….. Platyconchoecia
Other features. Md Exp large, elongate, leaf-like and without seta; ventral seta on
P6 Cxp2 has strongly expanded basis; 7
th
and 8
th
claws of CF weakest and longer than
shortest 6
th
claw. (Pls 52J, L, O, P, 53M, P, Q, T).
6a RAG slightly moved dorsally or in usual place near PVC ……………………………..………. 7
7 L usually > 2 mm; RAG slightly moved dorsally; females have LGGs near PDCs ...……….…. 8
7a L < 2 mm; RAG placed near PVC; LGGs near PDCs absent ………………...………………… 9
8 L usually < 3 mm; carapace elongated, H/L < 50% (Pl. 4C) ………….…….…….. Paramollicia
8a L > 3 mm; carapace shortened, H/L > 50% (Pl. 4D) ………………………..…….……. Mollicia
9 Right LGG placed just over RAG, not on posterior margin (Pl. 4E) ……………...…. Loricoecia
9a Right LGG placed on posterior margin just above RAG (Pl. 5A) ……….….. Pseudoconchoecia
10 Carapace globular, H/L > 60% (Pl. 5B) ……….....…………………..……….. Mikroconchoecia
Other features. Rostrum more or less bent downward in females, it’s almost straight
in males; LAG opens just at PDC; 3 or 4 sensory setae on female An1 and a-seta on male
An1 are bifurcate; male An1 e-seta has a single row of small pegs. (Pls 32E, F, 33D, E, F,
34D, E, 35C, D, E).
10a Carapace more elongated; H/L < 55% ..…………….…………….………………...….……… 11
11 Carapace thick; its posterior margin usually slightly uneven due to
the presence of larger medial gland cells (Pl. 5C) ..……..…………….…….… Orthoconchoecia
Other features. In males An2 Enp2 with exceptionally long c-seta (Pls 37H, 39H);
females have in its place a seta not shorter than Enp2 (Pls 36G, 38G).
11a Carapace less thick; its posterior margin even ……………………..……………..……….…....12
Other features. In males An2 Enp2 with relatively short c- and d- setae;
in females usually c- and d- setae absent or far shorter than Enp2 (as in Pl. 24F).
12 Dorsal and posterior margins of carapace form more or less acute angle, forward
posterior margin sloped; PDCs usually without spines (Pl. 5D) …………..…...…. Conchoecetta
Other features. In both sexes An2 Enp with short ( ~ 1/3 of longest g-seta in females,
~ 1/5 in males) and thin h-, i- and j- setae having clearly differing lengths (Pls 11G,
12E, 13I, 14G).
* In one case the carapace valves have LGGs near PVCs (Pl. 6A, C. lophura) but these are small and consist of only a few
gland cells.
30 Inna Drapun & Sharon L. Smith
12a Angle between dorsal and posterior margins of carapace close to right or obtuse;
right PDC with spine or without it, left one always without spine ……………..………..…....13
Other features. In both sexes An2 Enp with h-, i- and j- setae having similar lengths;
in females these setae relatively long, not shorter than 1/2 of longest g-seta.
13 Carapace rather short (H ~ 50% L), laterally shaped as rectangle with broadly
rounded corners; both PDCs always without spines; RAG always in usual
place near PDC (Pl. 6A, B) …….………...................................................................................14
Other features. b-seta on male An2 Enp1 with long hairs near its base (as in Pl. 57I).
13a Carapace elongated (H/L<50%), its anterior part tapered anteriorly; right PDC with more
or less developed spine or without it, sometimes 1–2 additional small spines present;
RAG either near PDC or moved forward (Pl. 7A–C) .…………………………...……..…......15
Other features. b-seta on male An2 Enp1 without long hairs.
14 Mean H/L slightly more than 50% (Pl. 6A) ……………………................….…….. Conchoecia
Other features. Capitulum of female FO turned downward (Pls 15E, D, 18C, D);
male An2 Enp3 with bare j-seta (Pls 16H; 17H; 19I).
14a Mean H/L slightly less than 50% (Pl. 6B) …...………………………….……….…... Porroecia
Other features. Female FO straight (Pls 54C, 56C, 58C);
male An2 Enp3 has j-seta with short hairs on its base (Pls 55G, 57H, 59G, H).
15 Carapace with distinct anterior-ventral striation (Pl. 7A) ………..……....……. Paraconchoecia
Other features. In females: FO clear divided on stem and capitulum; An1 e-seta
has long hairs on proximal half of anterior side (Pls 40D, 42D, 44C, 46D, 48D);
in males: FO capitulum elongated, without long hairs ventrally; ventral terminal seta
on P6 thinner and without long hairs (Pls 41D, O, 43D, 45D, 47D, Q, 49D, N).
15a Carapace delicate, usually without striae (Pl. 7B, C) ..……………………..………..…......... 16
Other features. In females: FO with no clear division on stem and capitulum;
An1 e-seta without long hairs on proximal half of anterior side (as in Pl. 24D, 64E);
in males: capitulum of FO either short and usually bare (as in Pl. 25D), or elongated and
with long hairs ventrally (as in Pl. 65E); all 3 terminal setae on P6 with long hairs distally.
16 RAG always located in usual place near PVC (Pl. 7B) …….....……..…..…… Discoconchoecia
Other features. In females: FO relatively short, not more then 1.5 times longer
than An1, and bare (Pls 24D, 26D, 28D);
in males: instead of spine comb, An1 e-seta has a characteristic oval plate formed
of long hairs cemented together (Pls 25E, 27F, 29G).
16a RAG most often moved anteriorly (Pl. 7C) ........…...……………................……… Proceroecia
Other features. In females: FO long, not less than 2 times longer than An1,
usually with short hairs distally (Pls 60E, 62D, 64E, 66D, 68D);
in males: An1 e-seta has a comb of paired spines (Pls 61F, 63F, 65G, 67F, 69G).
Halocyprid Ostracods of the Arabian Sea Region 31
Plate 3. Carapace outlines of the members of different genera in the tribe Conchoeciini. A Conchoecilla.
BConchoecissa. C Macroconchoecia.
All drawings in the Plates 3–7 are represented in the same scale.
32 Inna Drapun & Sharon L. Smith
Plate 4. Carapace outlines of the members of different genera in the tribe Conchoeciini. AAlacia.
BPlatyconchoecia. CParamollicia. DMollicia. E Loicoecia.
Halocyprid Ostracods of the Arabian Sea Region 33
Plate 5. Carapace outlines of the members of different genera in the tribe Conchoeciini. APseudoconchoecia.
BMikroconchoecia. COrthoconchoecia. DConchoecetta.
34 Inna Drapun & Sharon L. Smith
Plate 6. Carapace outlines of the members of different genera in the tribe Conchoeciini. AConchoecia.
BPorroecia.
Halocyprid Ostracods of the Arabian Sea Region 35
Plate 7. Carapace outlines of the members of different genera in the tribe Conchoeciini. AParaconchoecia.
BDiscoconchoecia. CProceroecia.
36 Inna Drapun & Sharon L. Smith
Genus Alacia Poulsen, 1973
The main genus character is the presence of 2–4 LGGs on each valve of carapace or only
on left one in both sexes (Poulsen, 1973). There is an opinion that “the present genus is almost
certainly arti cial and will need to be split up” (Angel et al., 2008).
Two species of the genus Alacia have been found in the analyzed material: A. alata (Müller,
1906) and A. leptothrix (Müller, 1906) (Table 3, Appendix 2). Both are described here (only
female in A. leptothrix).
Key to the species of Alacia (adult females and males):
1 L < 2.5 mm; H/L > 50%;
carapace with wing-like extensions of shoulder vaults ending in pointed angle;
its surface without distinct striation;
both PDCs has pointed spines;
lengths of all claws on CF evenly decrease from 1
st
to 8
th
(Pls 4A, 8A–C, N, 9A–D) ......................................................................………….……. A. alata
1a L > 3 mm; H/L < 50%;
carapace with no wing-like extensions of shoulder vaults;
its surface with distinct striae along ventral margin;
both PDCs rounded, with no spines;
5
th
–8
th
claws on CF much shorter and weaker than rsts
(Pls 4A, 10A–C, O) ………………………………………………………….......... A. leptothrix
Halocyprid Ostracods of the Arabian Sea Region 37
Alacia alata (Müller, 1906)
(Pict. 2; Pls 8, 9; Figs 11, 12)
Conchoecia alata Müller, 1906a, p. 121, pl. XXIX gs 1–10.
Alacia alata alata: Poulsen, 1973, p. 196, g. 102.
Alacia cf. alata: Martens, 1979, p. 362.
Alacia alata: Angel, 1999, pp. 819, 835, g. 9.25; Chavtur & Rzhanikova, 2004, p. 238, g. 1I, J.
Pict. 2. Alacia alata. A – female; B – male.
Females. L = 2.01–2.36 mm (2.20 ± 0.08 mm; N = 70); H/L = 57.8 ± 2.3% (N = 33).
Plate 8AN. Carapace (AC): slightly tapered anteriorly; with pointed spines on
both PDCs; both shoulder vaults have wing-like extensions pointing posteriorly; LAG and
RAG in usual places; posterior margin of each valve with 3 LGGs: 1 LGG just below PDC;
2 others on posterior margin near PVC, just above RAG on right valve. FO (D): capitulum
with strong spines on ventral surface and proximally on dorsal one; distal part of dorsal
surface covered with tiny spines; tip broadly pointed. An1 (D): with rather long dorsal seta;
shaft with tiny hairs on distal parts of 1
st
and 2
nd
segments and with longer ones on dorsal
surface of 4
th
segment; e-seta bears short hairs along its posterior surface becoming shorter
and denser more distally; sensory setae (a–d setae) ~ 3 times shoter than e-seta. An2 (E, F):
Prp with medial bulge covered with hairs; Enp1 with a- and b- setae having very ne spines;
Enp2+3 has c- or d- seta. Lb (G): dorsal projection almost rectangular. Md (H, I): Bsp
with epipodial seta; Enp1 with 4 ventral setae (1 or more of shorter setae plumose) and non-
plumose dorsal seta. Mx (J): Bsp with single seta not reaching distal edge of Enp1; Enp1 has
6 setae on anterior side, 3 setae on posterior, 1 laterally and a few short spines near distal edge.
P5 (K): Cxp1 partly covered with rather long hairs; Cxp2 with small spines; Cxp3 has 6 setae
in ventral group; Bsp with 7 setae in proximal ventral group (one of them very short and
one plumose), 3 setae in distal group, 1 plumose dorso-lateral and 1 long dorsal (vestige of
Exp). P6 (L): Cxp2 with 2 long plumose setae; Bsp with 5 long plumose ventral setae (most
distal of them reaches almost middle of Enp2), plumose dorso-lateral seta and short dorsal
seta (vestige of Exp). P7 (M): longer terminal seta ~ 3 times more than shorter seta; longer
seta with spines proximally. CF (N): dorsal unpaired seta present; lengths of all claws evenly
decrease from 1
st
to 8
th
.
Males. L = 1.73–2.08 mm (1.87 ± 0.07 mm; N = 72); H/L = 53.5 ± 2.0% (N = 35).
Plate 9AP. Carapace (AD): more elongated than in females, slightly tapered anteriorly;
with pointed spines on both PDCs, and with wing-like extension of shoulder vaults; in addition to
3 pairs of LGGs (as in female), has MGG on each valve above posterior dorsal LGG. FO (E): capi-
tulum with spines on ventral surface and proximally on dorsal, which are weaker than in female.
An1 (E, F): shaft bare; armature of e-seta consists of ~ 45 densely sitting, “umbrella”-shaped
38 Inna Drapun & Sharon L. Smith
Plate 8. Alacia alata, female. Carapace: A – lateral; B – ventral; C – both valves outside: posterior margins.
D – FO and An1. An2: E – Prp and Exp; F – Enp. G – Lb. Md: H – Bsp, Enp and Exp; I – coxal endite.
J – Mx. K – P5. L – P6. M – P7. N – CF.
Halocyprid Ostracods of the Arabian Sea Region 39
Plate 9. Alacia alata, male. Carapace: A – lateral; B – dorso-lateral; C – ventral; D – both valves outside:
posterior margins. E – FO and An1. F An1: armature of e-seta. An2: G – Prp and Exp; H – left Enp;
I – right Enp; J – left hook appendage. K – Lb. L – Md without Cxp. M – P5. N – P6. O – P7. P – CA.
40 Inna Drapun & Sharon L. Smith
(term of Poulsen, 1973), alternated spines; b- and d- setae bare. An2 (GJ): hook appendages
strongly curved, its two arms form acute angle; e-seta present. Lb (K): in dorsal projection
more elongated than in female; anterior part with rounded corners. Md (L): 3 shorter ventral
setae and dorsal seta plumose. Mx, P5 (M), P7 (O), CF: similar to those in female. P6 (N): all
setae on Cxp, Bsp and Enp1–2 shorter than in female; all 3 terminal setae on Enp3 about equal
and with long hairs. CA (P): elongated, with 6–7 muscles, end rounded.
Distribution. Alacia alata is recorded from all oceans, generally in the tropical zone;
often associated with upwelling centres; predominantly shallow mesopelagic species (Angel
et al., 2008). In the investigated area, A. alata was found mainly from the upwelling zones
along the shores of Somalia and Oman (Fig. 11), in 34% of tows. Maximum abundances were
recorded at depths 150–300 m (Fig. 12).
Fig. 11. Occurrence of Alacia alata at the stations listed in Table 1.
Сircles represent stations sampled, closed circles represent stations
where adults and juveniles of the species were found.
Fig. 12. Occurrence of Alacia alata at different depths. X-axis
represents the number of records of the species as a percentage of the
total number of tows (Table 2) in the corresponding layers.
0
100
200
300
400
500
600
700
800
900
1000
1100
1200
1300
1400
1500
0 20406080%
Depth, m
0
100
200
300
400
500
600
700
800
900
1000
1100
1200
1300
1400
1500
0 20406080%
Depth, m
Halocyprid Ostracods of the Arabian Sea Region 41
Alacia leptothrix (Müller, 1906)
(Pict. 3; Pl. 10; Fig. 13)
Conchoecia leptothrix Muller, 1906a, p. 122, pl. XXIX gs 20–26.
Alacia leptothrix: Poulsen, 1973, p. 202, g. 106; Angel, 1999, pp. 819, 835, g. 9.28 (male).
Pict. 3. Alacia leptothrix. Female.
Females. L = 3.30–3.35 mm; H/L = 47.5 ± 1.5%; N = 2.
Plate 10AO. Carapace (AC): elongated; with distinct striae along ventral edge;
PDCs rounded; H
ant
~ H
post
; posterior edge of each valve with 3 LGGs: 1 LGG opens on PDC,
2 others near PVC, just above RAG on right valve; LAG and RAG in usual places. FO (D):
~ 2 times longer than An1; 2/3 ventral surface of capitulum and its dorsal surface proximally
covered with spines; tip rounded. An1 (D): with long dorsal seta; 1
st
and 2
nd
segments have tiny
hairs mainly on ventral surface; below sensory setae, e-seta with short spines along its posterior
and partly anterior sides; sensory setae a little shorter than half e-seta. An2 (E, F): Prp with medial
bulge covered with hairs; a- and b- setae on Enp1 bare; Enp2+3 without c- and d- setae. Lb (G):
dorsal projection slightly tapered toward anterior edge that is rounded and covered with tiny spines.
Md (HJ): epipodial appendage with large seta having a few short spines; Enp1 with 4 ventral setae
and 1 dorsal seta; all setae non-plumose. Mx (K): Bsp with single seta not reaching distal edge of
Enp1; Enp1 with 6 setae on anterior side, 3 on posterior, 1 laterally and 6 short spines near distal edge.
P5 (L): Cxp3 with 6 setae in ventral group; Bsp with 6 setae in proximal ventral group (one of
them plumose) and 3 in distal; lengths of 2 longer terminal setae on Enp2 about equal. P6 (M):
Bsp with ventral setae, which are shorter than those in A. alata (Pl. 8L); most distal of them
reaches base of Enp2; dorsal seta (vestige of Exp) very short. P7 (N): shorter terminal seta about
half of longer one. CF (O): unpaired dorsal seta present; lengths of all claws unevenly decrease
from 1
st
to 8
th
: 2
nd
and 3
rd
claws about equal, 4
th
about two thirds of 3
rd
, 5
th
8
th
noticeable shorter
and weaker than 1
st
to 4
th
claws.
42 Inna Drapun & Sharon L. Smith
Plate 10. Alacia leptothrix, female. Carapace: A – lateral; B – ventral; C – both valves outside: posterior margins.
D – FO and An1. An2: E – Prp and Exp; F – Enp. G – Lb. Md: H – Bsp, Exp and Enp; I – epipodial seta; J – coxal
endite: toothed edge and distal tooth-list. K – Mx. L – P5. M – P6. N – P7. O – CF.
Halocyprid Ostracods of the Arabian Sea Region 43
Distribution. The majority of records of Alacia leptothrix are from low latitudes in
the Indian Ocean and Indonesian Sea. In the tropical Atlantic Ocean species is rare. The main
vertical distribution is between 500 and 2000 m (Angel et al., 2008). In the investigated area,
A. leptothrix was found only at two stations (Fig. 13) in the layer 250–500 m.
Fig. 13. Occurrence of Alacia leptothrix at the stations listed in Table 1. Circles represent stations sampled, closed
circles represent stations where females of species were found.
44 Inna Drapun & Sharon L. Smith
Genus Conchoecetta Claus, 1890
Dorsal and posterior margins of carapace form more or less acute angle, forward posterior
margin sloped. In males, the surface of carapace covered with rare long hairs. Setae h-, i- and j-
on An2 Enp are short and thin, and have clearly differing lengths (j-seta is shortest), especially
in females. Juvenile specimens of this genus are distinguished from those of other halocyprids
by having rostrum pointed in two places: as usual at the tip of rostrum and laterally (Poulsen,
1969, 1973; Deevey, 1968a).
There are two species in the genus Conchoecetta, and both species have been found in
the analyzed material: C. acuminata Claus, 1890 and C. giesbrechti (Müller, 1906) (Table 3,
Appendix 2). Both species are described below.
Key to the species of Conchoecetta:
Adult females:
1 L > 2.5 mm;
carapace dorsal and posterior margins form acute angle 55–60
o
;
An2 Enp2+3 with j-seta having basal part not swollen
(Pls 5D, 11A, H) ................................................................................................….. C. acuminata
1a L < 2.5 mm;
carapace dorsal and posterior margins form acute angle 78–80
o
;
j-seta on An2 Enp2+3 with bulbous basal part
(Pls 5D, 13A, J) …….………………………………………….………..........….. C. giesbrechti
Adult males:
1 L > 2 mm;
carapace dorsal and posterior margins form acute angle ~ 70
o
;
An1 e-seta has a comb with ~ 25 pairs of broad short spines;
An2 Enp3 with j-seta having basal part not swollen
(Pls 5D, 12A, C, F) .................................................................................................. C. acuminata
1a L usually < 2 mm;
carapace dorsal and posterior margins form acute angle 78–80
o
;
An1 e-comb with 33–37 pairs of broad short spines;
j-seta on An2 Enp3 with bulbous basal part
(Pls 5D, 14A, E, H) ……………….…...…………………………………....…… C. giesbrechti
Halocyprid Ostracods of the Arabian Sea Region 45
Conchoecetta acuminata Claus, 1890
(Pict. 4; Pls 11, 12; Figs 14, 15)
For synonymy before 1906, see Müller, 1906a.
Conchoecia acuminata: Müller, 1906a, p. 76, pl. XV gs 17–23; Deevey, 1968a, p. 48, g. 19; Poulsen, 1969a,
p. 149, g. 8a, c.
Conchoecetta acuminata: Poulsen, 1973, p. 59, g. 28; Angel, 1999, pp. 819, 833, g. 9.31.
Pict. 4. Conchoecetta acuminata. Female.
Females. L = 2.75–2.90 mm; H/L = 39.0 ± 2.3%; N = 2.
Plate 11AP. Carapace (AC): elongated, tapered anteriorly; PDCs without spines; dorsal
and posterior margins form acute angle 55–60
o
; RAG opens on PVC, LAG somewhat moved
forward along dorsal margin. FO (D): no clear division into shaft and capitulum; the latter is bare,
its tip with a rather long narrow nger-like process. An1 (D): 2
nd
segment with short dorsal seta;
e-seta bears tiny spines along posterior side terminally; sensory setae ~ 3 times shorter than e-seta.
An2 (EH): inner side of Prp bare; processus mammillaris on Enp1 rounded; a- and b- setae bare;
c- and d- setae missing; j-seta noticeably shorter than h- and i- setae, its basal part without bulge.
Lb (I): dorsal projection tapered anteriorly, its anterior edge almost straight, with rounded corners
that are covered with tiny spines. Md (JL): epipodial appendage on Bsp with strong short
seta; Enp1 arms non-plumose dorsal seta and 3 ventral setae. Mx (M): Bsp with single seta not
reaching distal edge of Enp1; Enp1 has 6 short spines near distal edge. P5 (N): Cxp3 with 6 setae
in ventral group; Bsp has 6 setae in proximal ventral group (one of them plumose) and 3 setae in
distal group; epipodite with 4, 5 and 4 long plumose setae in each of three groups. P6 (O): Cxp2
bears 2 plumose setae; Bsp has short dorsal (vestige of Exp) and dorso-lateral setae, and rather
long ventral setae (most distal of them reaches half Enp2); epipodite with 5, 5 and 6 long plumose
setae in each of three groups. P7 (P): both terminal setae are bare.
Male. L = 2.10 mm; H/L = 43.2%.
Plate 12AQ. Carapace (A): PDCs with no spines; dorsal and posterior margins form
acute angle ~ 70
o
; MGGs present; surface with rarely placed long hairs. FO (B): capitulum with
spines on proximal 2/3 of ventral surface and a few spines on dorsal surface proximally; its tip
rounded. An1 (B, C): armature of e-seta has a comb with ~ 25 pairs of rather broad short spines
directed proximally and one pair of spines directed distally just below the comb; in upper part of
comb some of spines sit alternately; b- and d- setae with a few short hairs on level with distal
part of e-seta comb. An2 (DG): processus mammillaris on Enp1 rounded; a- and b- setae
bare; e-seta not visible, possibly absent; h-, i- and j- setae have differing lengths; j-seta shortest
and with basal part not swollen; each of hook appendages have 2 processes on inner surface of
basal part and terminate in 2 tiny papillae. Lb (H): in dorsal projection more elongated than in
female. Md (I, J): Enp1 with non-plumose dorsal seta. Mx (K): Enp1 has 7 short broad
spines near distal edge. P5 (L): Bsp has 7 setae in proximal ventral group (6 setae in female).
46 Inna Drapun & Sharon L. Smith
Plate 11. Conchoecetta acuminata, female. Carapace: A – lateral; B – ventral; C – both valves outside: PDCs.
D – FO and An1. An2: E – Prp and Exp; F – Exp2–9; G, H – Enp. I – Lb. Md: J – Cxp; K – coxal endite: toothed
edge and distal tooth-list; L – Bsp, Exp and Enp. M – Mx. N – P5. O – P6. P – P7.
Halocyprid Ostracods of the Arabian Sea Region 47
Plate 12. Conchoecetta acuminata, male. Carapace: A – both valves outside. B – FO and An1.
CAn1: armature of b-, d- and e- setae. An2: D – Prp and Exp; E – left Enp; F – right Enp; G – left
hook appendage. H – Lb. Md: I – Bsp and Exp; J – Enp. K – Mx. L – P5. M – P6. N – P6: epipodite.
O – P7. P – CA. Q – CF.
48 Inna Drapun & Sharon L. Smith
P6 (M, N): all setae on Bsp and Enp1–2 present but considerably shorter than in female; all
terminal setae on Enp3 about equal and with long hairs. P7 (O): similar to that in female.
CA (P): elongated, tapered to end that is rounded, has 8 muscle bands. CF (Q): unpaired dorsal
seta present.
Distribution. Conchoecetta acuminata is recorded from all oceans (mostly from
the latitudes <40°), but seldom in abundance; predominantly shallow mesopelagic species
(Angel et al., 2008). In the Arabian Sea Region, C. acuminata was found in the southern