Corresponding author: Khwanruan Srinui (
Academic editor: K.H. George
A new species of
Srinui K, Ohtsuka S, Metillo EB, Nishibori M (2019) A new species of
The planktonic calanoid copepod genus
The
The common
During our copepod surveys in southeastern Asia, we found an undescribed species of
The material examined was collected from three sites: Carigara Bay, Leyte Island, the Philippines (
Distribution of
The structure of female and male antennules follows a pattern of the basically uniramous 28 segments. The antennules of both sexes are similar except for the geniculate right antennule in calanoid copepods as in the copepodid I (CI) setation pattern (
In this study, we used adults of the undescribed species
DNA sequences were manually edited using Sequence Scanner version 1.0 (Applied Biosystems) and compared with the GenBank:
Type locality: Carigara Bay, Off Leyte Island, the Philippines (
Holotype: ♀, dissected and mounted on 2 glass slides (BIMS–Zoo–0267); paratype (allotype): 1 ♂, dissected and mounted on 2 glass slides (BIMS–Zoo–0268); additional paratypes: 4 ♀, 3 ♂ partially dissected and mounted on 3 glass slides (BIMS–Zoo–0269).
Female. Total length, 1.19–1.23 mm (mean ± SD = 1.21 ± 0.01 mm,
Female. Body (Fig.
Antennule (Fig.
Antenna (Fig.
Mandible (Fig.
Maxillule (Fig.
Maxilla (Fig.
Maxilliped (Fig.
Legs 1 to 4 (Fig.
Coxa | Basis | Exopod segment | Endopod segment | ||||
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1 | 2 | 3 | 1 | 2 | |||
Leg 1 | 0-0 | 0-0 | 1-1; I-1; 2,I,4 | 0-1; 1,2,3 | |||
Leg 2 | 0-0 | 0-0 | 0-1; 0-1; 0,I,5 | 0-2; 1,2,4 | |||
Leg 3 | 0-0 | 0-0 | 0-1; 0-1; 0,I,5 | 0-2; 1,2,4 | |||
Leg 4 | 0-0 | 1-0 | 0-1; 0-1; 0,I,5 | 0-3; 1,2,3 |
Leg 5 (Fig.
Male. Body (Fig.
SEM micrographs of
Left antennule (Fig.
Right antennule (Fig.
Leg 5 (Fig.
The absence of paired dorsal processes on the female genital double-somite and the thick rostrum were confirmed with scanning electron microscopy (Fig.
SEM observations of the male urosomite clearly showed fine ornamentation on the posterior border of first urosomite (Fig.
The subgenus
Among the
Differences in morphological characteristics among
Features | |||
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Setae on segment (5) VII of right antennule | 1 seta | Absent | 1 seta |
Paired posterior dorsolateral processes on the genital double-somite | Absent | Present | Present |
Length of dorsal processes on the second urosomite relative to the posterior border of the anal somite | Reaching posterior border of anal somite | Half of length | Half of length |
Length ratio of lateral to terminal setae of leg 5 | 1.3 | 2 | 1 |
Mandibular processes | 1 blunt and 2 cuspidate | 1 blunt covered with chitosan and 6 cuspidate | 5 cuspidate |
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Length of dorsal and lateral spines on second somite | Medium | Long | Short |
Presence of three rows of spinules ventrolaterally on second somite | Present | Present | Absent |
Dorsal processes of third urosomite long enough to reach beyond those of fourth urosomite | Reaching | Not reaching | Not reaching |
Insertion of inner seta on second exopod segment of left leg 5 | Midway | Subterminal | Subterminal |
Shape of medial projection on second exopodal segment of right leg 5 | Irregular triangular | Rounded triangular | Quadrate |
*According to Ueda and Bucklin, 2006.
Since “
The taxonomy of the Indo-West Pacific
The new species of
We obtained sequence data from mitochondrial 16S and COI genes for 14 individual specimens at three sites. A 282 bp fragment of the 16S gene was analyzed for five adult female specimens from the Philippines (
Neighbor-joining phylogenetic tree based on the mitochondrial 16S (
Pairwise differences for 16S and COI sequences between individual females of
16S | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | |
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1 |
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2 |
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0.000 | |||||||||||||||
3 |
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0.000 | 0.000 | ||||||||||||||
4 |
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0.000 | 0.000 | 0.000 | |||||||||||||
5 |
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0.000 | 0.000 | 0.000 | 0.000 | ||||||||||||
6 |
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7 |
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0.006 | |||||||||||
8 |
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0.019 | 0.013 | ||||||||||
9 |
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0.013 | 0.006 | 0.019 | |||||||||
10 |
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0.025 | 0.019 | 0.031 | 0.025 | ||||||||
11 |
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0.025 | 0.019 | 0.031 | 0.025 | 0.000 | |||||||
12 |
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0.025 | 0.019 | 0.031 | 0.025 | 0.000 | 0.000 | ||||||
13 |
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0.025 | 0.019 | 0.031 | 0.025 | 0.000 | 0.000 | 0.000 | |||||
14 |
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0.013 | 0.006 | 0.019 | 0.013 | 0.013 | 0.013 | 0.013 | 0.013 | ||||
15 | 0.206 | 0.206 | 0.206 | 0.206 | 0.206 | 0.006 | 0.000 | 0.013 | 0.006 | 0.019 | 0.019 | 0.019 | 0.019 | 0.006 | |||
16 | 0.287 | 0.287 | 0.287 | 0.287 | 0.287 | 0.287 | 0.281 | 0.281 | 0.287 | 0.275 | 0.275 | 0.275 | 0.275 | 0.281 | 0.281 | ||
17 | 0.313 | 0.313 | 0.313 | 0.313 | 0.313 | 0.356 | 0.350 | 0.338 | 0.350 | 0.344 | 0.344 | 0.344 | 0.344 | 0.350 | 0.350 | 0.331 | |
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1 |
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2 |
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0.008 | |||||||||||||||
3 |
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0.002 | 0.009 | ||||||||||||||
4 |
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0.008 | 0.003 | 0.009 | |||||||||||||
5 |
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0.000 | 0.008 | 0.002 | 0.008 | ||||||||||||
6 |
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7 |
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0.019 | |||||||||||
8 |
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0.017 | 0.020 | ||||||||||
9 |
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0.017 | 0.011 | 0.019 | |||||||||
10 |
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0.024 | 0.024 | 0.022 | 0.022 | ||||||||
11 |
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0.030 | 0.030 | 0.028 | 0.028 | 0.009 | |||||||
12 |
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0.024 | 0.024 | 0.022 | 0.003 | 0.022 | 0.006 | ||||||
13 |
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0.025 | 0.025 | 0.024 | 0.024 | 0.005 | 0.008 | 0.002 | |||||
14 |
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0.025 | 0.025 | 0.024 | 0.024 | 0.011 | 0.020 | 0.014 | 0.016 | ||||
15 | 0.167 | 0.172 | 0.169 | 0.172 | 0.167 | 0.009 | 0.009 | 0.011 | 0.008 | 0.014 | 0.020 | 0.014 | 0.016 | 0.016 | |||
16 | 0.220 | 0.220 | 0.222 | 0.220 | 0.220 | 0.241 | 0.241 | 0.233 | 0.239 | 0.231 | 0.235 | 0.231 | 0.233 | 0.235 | 0.231 | ||
17 | 0.243 | 0.244 | 0.244 | 0.244 | 0.243 | 0.247 | 0.252 | 0.244 | 0.249 | 0.250 | 0.249 | 0.247 | 0.249 | 0.252 | 0.243 | 0.247 |
Temperature and salinity appear to be important factors determining the distribution and abundance of copepods. In the Indo-West Pacific,
In the tropical zone,
In Bintulu, Sarawak, Malaysia,
Ranges of salinity and temperature of three
Prior to the current study, it was believed that
Mitochondrial markers within the 16S and COI genes have proved to be of great utility in investigating the systematics of ecologically and geographically isolated populations of calanoid copepods (
Thirteen species of the subgenus
1 | Genital double-somite lacking posterodorsal sharp processes |
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– | Genital double-somite having paired posterodorsal processes |
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2 | Ventroposterior corners of prosome acutely pointed, reaching beyond half of genital double-somite |
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– | Ventroposterior corners of prosome round with pair of acutely pointed processes not reaching beyond half of genital double-somite |
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3 | Second segment of antennule with strong curved processes posteriorly |
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– | Second segment of antennule without strong curved processes |
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4 | First antennule segment with two large processes terminally |
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– | First antennule segment lacking processes |
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5 | Exopod of leg 5 thickened proximally |
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– | Exopod of leg 5 not thickened proximally |
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6 | Exopod of leg 5 thickened proximally extending midway along exopod |
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– | Exopod of leg 5 with thickened proximal part confined to base of exopod |
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7 | Length ratio of outer basal setae to exopod of leg 5: ca 2 |
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– | Length ratio of outer basal setae to exopod, leg 5: ca 1 |
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8 | Caudal ramus longer than wide by at most ca 2 times; second free urosomite with small spinules dorsally and posteriorly |
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– | Caudal ramus longer than wide by ca 3 times; second free urosomite lacking small dorsal spinules |
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9 | Fifth to seventh antennule segments each with posterior hook; genital double-somite with two pairs of small processes dorsally |
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– | Fifth to seventh antennule segments each lacking hook posteriorly; genital double-somite with pair of small processes dorsally |
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10 | First antennule segment with 2 or more strong processes distally |
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– | First antennule segment with single strong process distally |
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11 | Second antennule segment with single spinule posteriorly |
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– | Second antennule segment with 4 spinules posteriorly |
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12 | Caudal ramus with 4–6 rows of minute spinules dorsally |
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– | Caudal ramus lacking of dorsal rows of spinules |
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1 | Urosomite 3 with large spine-like processes dorsally |
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– | Urosomite 3 without spine-like processes dorsally |
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2 | Dorsal processes of urosomite 3 long, reaching half-length of anal somite |
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– | Dorsal processes of urosomite 3 short, reaching posterior-most border of urosomite 4 |
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3 | Urosomite 4 with four spine-like processes between pair of dorsal processes |
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– | Urosomite 4 lacking spine-like processes between pair of dorsal processes |
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4 | Genital somite lacking spinular rows along posterodorsal border |
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– | Genital somite with spinular rows along posterodorsal border |
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5 | Inner projection of first exopodal segment of right leg 5 quadrate |
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– | Inner projection of first exopodal segment of right leg 5 irregularly triangular |
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6 | Urosomites 3 and 4 each with two prominences between pair of dorsal processes |
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– | Urosomites 3 and 4 each lacking prominences between pair of dorsal processes |
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7 | Inner seta of terminal exopodal segment of left leg 5 longer than terminal segment |
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– | Inner seta of terminal exopodal segment of left leg 5 nearly equal to terminal segment |
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8 | Urosomite 4 without prominences dorsally |
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– | Urosomite 4 with prominences dorsally |
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9 | Number of dorsal prominences on urosomite 4 fewer than five |
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– | Number of prominences on urosomite more than seven |
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10 | Terminal exopodal segment of left leg 5 with three elements |
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– | Terminal exoposal segment of left leg 5 with single element |
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11 | Terminal element of left leg 5 spiniform |
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– | Terminal element of left leg 5 as fine seta |
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12 | Terminal elements of left leg 5 as three small prominence |
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– | Terminal elements of left leg 5 as two spines |
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We express our sincere thanks to Dr Mitsuyasu Moriya for his help with field sampling at Leyte Island in the Philippines. We are also grateful to Dr Wansuk Senanan of Burapha University for guidance on molecular techniques. Thanks are also due to Professor Ho Young Soh (Chonnan National University, Korea) who kindly provided us with specimens of