Research Article |
Academic editor: Danielle Defaye
© 2018 Chaichat Boonyanusith, Thanida Saetang, Koraon Wongkamheng, Supiyanit Maiphae.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Boonyanusith C, Saetang T, Wongkamheng K, Maiphae S (2018) Onychocamptus Daday, 1903 from Thailand, with descriptions of two new species and two new records (Crustacea, Copepoda, Harpacticoida, Laophontidae). ZooKeys 810: 45-89. https://doi.org/10.3897/zookeys.810.29253
|
In this paper, two new species of Onychocamptus Daday, 1903 are described from Thailand: Onychocamptus satunensis sp. n. and Onychocamptus tratensis sp. n. The following features mainly distinguish O. satunensis sp. n. from known species: internal sausage-like and internal rounded structures on cephalothorax and one outer seta on the male P5 exopod that is as long as the supporting segment. In contrast, the cephalothorax of O. tratensis sp. n. is smooth but has rounded integumental window-like structures, and the outer seta on the male P5 exopod is two times as long as the supporting segment. Onychocamptus anomalus shows the highest similarity with the two new species, but in contrast to both Thai species, it has only one seta on the exopod of the antenna. In addition, in the present study, two additional species, O. bengalensis and O. vitiospinulosa, are newly recorded in Thailand. Thus, the number of Onychocamptus species recorded in Thailand increases to five species. A key to all known species of this genus in the world is also proposed.
Laophontidae , Southeast Asia, stygobiont
The genus Onychocamptus comprises eight species: (1) Onychocamptus mohammed (Blanchard & Richard, 1891), the type species, with O. heteropus Daday, 1903 considered a junior synonym (
In Thailand, only one species, O. mohammed, had been reported (
Plankton samples were collected from the Samer-rach peat swamp (Trat Province) in eastern Thailand, and from the Prawattisart and Khao Thanan caves (Satun Province), Thale-Noi Lake (Pattalung Province), and Ta-pom swamp (Krabi Province) in southern Thailand (Fig.
Holotype. Adult female, dissected and mounted onto one slide, collected from type locality on 30 July 2015 (PSUZC-PK2002-01). Allotype. One adult male, dissected and mounted onto one slide, (PSUZC-PK2002-02), all collected from type locality on 20 January 2016. Paratypes. One undissected adult ovigerous female paratype mounted onto one slide (PSUZC-PK2002-03), and one undissected adult male paratype, mounted onto one slide (PSUZC-PK2002-04), coll. C Boonyanusith and K Wongkamheng; type locality on 30 July 2015 and 20 January 2016, respectively.
One adult ovigerous female and one adult male, both collected from type locality on 2 April 2015 and stored in 70% ethanol, deposited in the collection of the first author (CB).
Prawattisart cave, Muang district, Satun Province, southern Thailand, 6°42'55.82"N, 100°05'19.17"E. The cave is in an isolated, wedge-shaped, limestone hill. It is surrounded by irrigation canal and paddy fields, but there are no connections between water in and outside cave. Beyond entrance of the cave there is a long horizontal gallery, with approximately 5–10 m high and approximately 2–3 m wide. At some place there are two openings, which are large enough for entry, indicating a complex tunnel system. The collecting point is a part of a large water body inside the cave, fulfilled by approximately 10–50 cm depth of water. Water depth varies according to season, but it has never dried out. Water was turbid and flowed slowly. Water temperature was 25.5 °C, pH 7.8, conductivity 360 µS cm-1, dissolved oxygen 4.9 mgL-1.
The specific name satunensis is derived from the name of Satun Province, where the species was collected. The name is a noun in the genitive singular, masculine.
Laophontidae. Body gradually tapering posteriorly. Cephalothorax with internal sausage-like structure, and internal rounded structures. Posterior margin of cephalothorax and body somites (except penultimate and anal somite) with sensillum-bearing tubercles. Second and third urosomite partly fused ventrally in female, representing genital double-somite. Caudal rami approximately 2.5 times as long as wide, with one transverse inner row of spinules near insertion of dorsal seta. Caudal seta IV and V fused. Allobasis of antenna without abexopodal seta. Endopodal lobe of P5 with three, and exopod with four pinnate setae. Male P3 enp-2 with apophysis on outer distal corner, reaching tip of enp-3. Exopod of male P5 with three setae, outer seta as long as supporting segment. Male P6 reduced, with outer seta and inner bipinnate seta apically; inner seta approximately twice as long as outer one.
Body (Fig.
Caudal rami (Figs
The ovigerous female bears one oval egg sac with eight eggs, located ventrally between pair of fifth legs.
Antennule (Fig.
Antenna (Fig.
Mandible (Fig.
Maxillule (Fig.
Maxilla (Fig.
Maxilliped (Fig.
P1 (Fig.
P2 (Fig.
P3 (Fig.
P4 (Fig.
Armature formula of P1−P4 as in Table
Armature formula of P1–P4 of Onychocamptus satunensis sp. n. and Onychocamptus tratensis sp. n.
Swimming legs | Basis | Exopod | Endopod | |
---|---|---|---|---|
P1 | female | I-I | I-0; III,2,0 | 0-0; 0,I1,0 |
male | I-I | I-0; III,2,0 | 0-0; 0,I1,0 | |
P2 | female | I-0 | I-0; I-1; III,2,1 | 0-0; 0,2,2 |
male | I-0 | I-0; I-1; III,2,1 | 0-0; 0,2,2 | |
P3 | female | 1-0 | I-0; I-1; III,2,1 | 0-0; 1,2,3 |
male | 1-0 | I-0; I-1; III,2,1 | 0-0; 0-1; 0,2,2 | |
P4 | female | 1-0 | I-0; I-1; II,2,1 | 0-0; 1,1,1 |
male | 1-0 | I-0; I-1; II,2,1 | 0-0; 1,1,1 |
P5 (Figs
P6 (Fig.
Body (Fig.
Caudal rami as in female (Fig.
Antennule (Fig.
Rostrum, antenna, mouthparts and P1, P2 (not shown) as in female.
P3 (Fig.
P4 (Fig.
Armature formula of P1–P4 as in Table
P5 (Fig.
P6 (Fig.
The right P2 enp-2 lacks the proximalmost inner seta (Fig.
Onychocamptus satunensis sp. n. is the only species of Onychocamptus with internal sausage−like structure on cephalothorax (Figs
Onychocamptus satunensis sp. n., Digital photographs (A, B) and SEM photographs. A–C cephalothorax (dotted line on figure B indicates margin of internal structures) D anal somite and caudal rami E male urosome, lateral view, arrow indicates setules F tip of female antennule, arrow indicates setules. Scale bars: 0.1 mm (A, C), 0.05 mm (B, D), 0.005 mm (E), 0.02 mm (F).
O. anomalus | O. bengalensis | O. besnardi | O. fratrisaustralis | O. krusensterni | O. mohammed | O. taifensis | O. vitiospinulosa | O. satunensis sp. n. | O. tratensis sp. n. | |
---|---|---|---|---|---|---|---|---|---|---|
Ornamentation on cephalothorax | smooth | smooth | smooth | smooth | smooth | smooth | smooth | smooth | internal sausage-like structure, and internal rounded structures | 1 middle and 2 lateral rounded integumental window-like structures |
Exp of antenna (setae) | 1, reduced | 4, well developed | 4, well developed | 4, well developed | 4, well developed | 4, well developed | 4, well developed | 4, well developed | 4, well developed | 4, well developed |
Lateral seta on exp of antenna | complete absent | pinnate spinulose seta | NA | pinnate spinulose seta | pinnate spinulose, seta | NA | bare, slender, short seta | bare, slender, short seta | pinnate spinulose, seta | pinnate spinulose seta |
Abexopodal seta of antenna | absent | present | present | present | present | present | absent | present | absent | absent |
P2 enp-2 (inner setae) | 2 | 2 | 2 | 2 | 2 | 2 | 1 | 2 | 2 | 2 |
P4 exp-3 (outer spines) | 2 | 3 | 2 | 2 | 2 | 3 | 3 | 3 | 2 | 2 |
P4 exp-3 (inner seta) | present | present | absent | present | present | present | present | present | present | present |
Female P5 exp and beseoendopod | separated | fused | separated* | separated | separated | separated | separated | separated | separated | separated |
Setae on female P5 exp:enp | 4:3 | 3:3 | 3:3 | 3:3 | 3:3 | 3:3 | 3:3 | 3:2 | 4:3 | 4:3 |
Setae on male P5 exp | 3 | 2 | 2 | NA | 2 | 2 | 2 | 2 | 3 | 3 |
Male P5, outer seta of exp | A | C | NA | NA | C | C | B | B | D | E |
CR (L:W ratio) | 2.7 | 3.0–6.0 | 2 | 2.2–3.0 | 2.0–3.0 | 2.4–3 | 1.8–2.0 | 1.8–2.2 | 2.5 | 2.2 |
Seta of male P6 | a | d | NA | NA | c | c | e | b | a | a |
Segment of male antennule | 6 | 6–7 | ? | NA | 6–7 | 7 | 7 | 7–8 | 8 | 8 |
Distribution | India | India, Japan, Korea, Australia | Brazil, Micronesia, NW Mexico | NW Mexico | Alaska | Cosmo-politan | China and Korea | Korea | Thailand | Thailand |
Ecology | Lake | Estuary | With marine algae | Estuary | Lagoon, 1 m | Cave, FW | Lake | Inland water | Cave | Peatswamp |
This species is known from the type locality only.
Holotype. Adult female, dissected and mounted onto two slides (PSUZC-PK2003-01–PSUZC-PK2003-02). Allotype. One adult male, dissected and mounted onto two slides (PSUZC-PK2003-03–PSUZC-PK2003-04). Paratypes. One undissected adult female, mounted onto one slide, (PSUZC-PK2003-05). One undissected adult male, mounted onto one slide, (PSUZC-PK2003-06). One adult female, dissected and mounted onto two slides, (PSUZC-PK2003-07–PSUZC-PK2003-08).
All specimens were collected by S Maiphae and T Saetang from type locality on 9 January 2017.
Ten females and five males, all collected from type locality on 9 January 2017 and stored in 70% ethanol, deposited in crustacean reference collection, Zoological Museum, Kasetsart University (ZMKU_CP).
Samer-rach peat swamp, Trat Province, eastern Thailand, 12°28'04.0"N, 102°21'20.6"E. Water temperature ranged between 28.83 °C, pH of 6.23, salinity 6.91 ppt, total dissolved solids 7.9 mg L-1, and dissolved oxygen 4.41 mg L-1.
The specific name tratensis is derived from the name of Trat Province, where the species was collected. The name is a noun in the genitive singular, masculine.
Laophontidae. Body gradually tapering posteriorly. One middle and two lateral rounded integumental window-like structures on cephalothorax. Second and third urosomite fused ventrally in female forming genital double-somite. Caudal rami cylindrical, both sides parallel, approximately 2.5 twice as long as wide, with one longitudinal row of minute spinules on inner margin near insertion of dorsal seta and horizontal row of minute spinules near insertion of inner terminal seta. Outer terminal seta (seta IV) fused at base with inner terminal seta. Allobasis of antenna without abexopodal seta. Endopodal lobe of P5 with two bipinnate and one plumose setae on inner margin and exopod of P5 with four plumose setae. Enp-2 of male P3 with apophysis on outer distal corner; apophysis reaching the tip of enp-3. Exopod of male P5 with three bipinnate setae, outer seta two times as long as supporting segment. P6 of the male reduced, with outer seta and inner bipinnate seta apically; inner seta approximately twice as long as outer one.
Body. Total body length, measured from tip of rostrum to posterior margin of caudal rami, 360–450 µm (mean 400 µm, n = 14; 420 µm in holotype); preserved specimen colourless. Body covered entirely with setules, cylindrical; gradually tapering posteriorly, with maximum width at posterior part of cephalothorax. Prosome 1.3 times as long as urosome (including caudal rami) (Fig.
Caudal rami (Fig.
Egg sac (Fig.
Antennule (Fig.
Antenna (Figs
Mandible (Fig.
Maxillule (Fig.
Maxilla (Fig.
Maxilliped (Fig.
P1 (Fig.
P2 (Fig.
P3 (Fig.
P4 (Fig.
Armature formula of P1–P4 as in Table
P5 (Figs
Body (Fig.
Caudal rami (Fig.
Antennule (Fig.
Rostrum, antenna (coxa, allobasis, and endopod), mouthparts, and P1 as in female.
P2 (Fig.
P3 (Fig.
P4 (Fig.
Armature formula of P1–P4 as in Table
P5 (Fig.
P6 (Fig.
In male, variability was observed in the exopod of antenna, four specimens with four setae and one specimen with five setae (Fig.
This species is known from the type locality only. It was found in two months, January and September 2017.
Laophonte bengalensis Sewell, 1934: 98, fig 10a−k.
Onychocamptus
bengalensis
:
Two females and two males from Khao Thanan cave, Satun Province, southern Thailand, 07°03'43.2"N, 99°41'42.7"E; coll. C Boonyanusith and K Wongkamhaeng; 12 December 2014. One female from Samer-rach peat swamp, Trat Province, eastern Thailand, 12°28'04.0"N 102°21'20.6"E.; coll. S Maiphae and T Saetang; 25 May 2017.
Laophontidae. Caudal rami more than four times as long as wide in female and approximately three times as long as wide in male. Female P5 exopod and baseoendopod fused, endopodal lobe and exopod with three setae each. P4 exp-3 with three outer spines.
Female (Fig.
Caudal rami (Fig.
Antennule and mouthparts as in O. satunensis sp. n. and O. tratensis sp. n., except for allobasis of antenna with one bipinnate abexopodal seta (Figs
P1 (Fig.
Armature formula of P1–P4 of Onychocamptus bengalensis, O. vitiospinulosa, and O. mohammed.
Swimming legs | Basis | Exopod | Endopod | |
---|---|---|---|---|
P1 | female | I-1 | I-0; III,2,0 | 0-0; 0,I1,0 |
male | I-1 | I-0; III,2,0 | 0-0; 0,I1,0 | |
P2 | female | I-0 | I-0; I-1; III,I1,1 | 0-0; 0,2,2 |
male | I-0 | I-0; I-1; III,I1,1 | 0-0; 0,2,2 | |
P3 | female | 1-0 | I-0; I-1; III,I1,1 | 0-0; 1,2,3 |
male | 1-0 | I-0; I-1; III,II,1 | 0-0; 0-1; 0,2,2 | |
P4 | female | 1-0 | I-0; I-1; III,2,1 | 0-0; 1,1,1 |
male | 1-0 | I-0; I-1; III,2,1 | 0-0; 1,1,1 |
P5 (Figs
P6 (Fig.
Body (Fig.
Caudal rami (Fig.
Antennule, antenna, mouthparts, P1, P2, P3 as in O. satunensis sp. n. and O. tratensis sp. n., except for P4 exp-3 with three robust outer spines (Fig.
Armature formula of P1–P4 as in Table
P5 (Fig.
P6 (Fig.
In male, one additional seta on left P1 enp-2 (Fig.
Onychocamptus bengalensis is characterised by the relatively long caudal ramus and fusion of exopod and baseoendopod of P5 in the female. The length:width ratio of caudal ramus in female is variable (three times as long as wide in
This species has been recorded from Calcutta (India) (
In this study, we found the species in i) Samer-rach peat swamp, Trat Province, eastern Thailand; water temperature, 27.65 °C; pH, 5.38; salinity, 6.06 ppt; conductivity, 11285.2 µS cm-1; total dissolved solids, 6982 mg L-1; dissolved oxygen, 3.86 mg L-1, ii) Khao Thanan cave, Satun Province, southern Thailand; this is a limestone cave which normally dries out during the dry season (April); water pH, 8.85; dissolved oxygen, 2.7 mg L-1; conductivity, 2.1 µS cm-1; salinity varies seasonally because of the effect from the sea nearby.
Laophonte vitiospinulosa Shen & Tai, 1963: 423, figs 42–46.
Onychocamptus
mahammed
vitiospinulosa
:
Onychocamptus
vitiospinulosa
:
Seven females and four males from Thale-Noi Lake, Pattalung Province, southern Thailand, 07°46'30.47"N, 100°9'31.68"E; coll. S Maiphae and T Saetang; 23 October 2013.
Laophontidae. Caudal rami more than 2.3 times as long as wide in female and approximately 1.8 times as long as wide in male. P4 exp-3 with three outer spines. Female P5 exopod and baseoendopod separated, with three bipinnate spiniform setae on exopod and two on baseoendopod. Exopod of P5 male with two bipinnate spiniform setae.
Body (Fig.
Caudal rami (Fig.
Egg sac (Fig.
Antennule and mouthparts as those of previous described species, but allobasis of antenna with one bipinnate abexopodal seta (Figs
P1, P2, P3 and P4 (Fig.
Armature formula of P1−P4 as in Table
P5 (Figs
P6. Reduced to minute, rectangular protuberance, with one naked seta.
Body (Fig.
Caudal rami (Fig.
Antennule, antenna, mouthparts, P1, P2, P3 (Fig.
Armature formula of P1–P4 as in Table
P5 (Fig.
P6 (Fig.
Thai specimens agree with Shen and Tai (1979), however the inner seta of the male P6 comes beyond the distal margin of four urosomite and the outer seta is approximately 1/3 as long as the inner seta in one specimen of our samples (Fig.
This species has been recorded from the delta of the Pearl River (Kwangtung Province, south China) (
In this study, we found this species only in Thale-Noi Lake, Pattalung Province (southern Thailand) in June, August, and October 2013. Water temperature ranged between 28.3–31.6 °C, pH of 5.22–7.83, salinity 0.1–1.2 ppt, conductivity 209.5–2385 µS cm-1, transparency 0.05–1.35 m, depth 0.35–1.65 m, chlorophyll a 0.27–37.53, and dissolved oxygen 2.89–5.76 mg L-1.
Laophonte
mohammed
Blanchard & Richard, 1891: 526, pl VI, figs 1–15;
Onychocamptus heteropus Daday, 1903: 157–161, figs18–24.
Laophonte calamorum Willey, 1923: 305, figs 2–4.
Onychocamptus
mohammed
:
Four females from Ta-pom swamp, Krabi Province, southern Thailand, 08°12'50.19"N 98°46'41.24"E, coll. S Maiphae and T Saetang, on 8 December 2016.
Laophontidae. Caudal rami more than 2.2 times as long as wide in female. P4 exp-3 with three outer spines. Baseoendopod and exopod separated, each with three bipinnate spiniform setae.
Body (Fig.
Caudal rami (Fig.
Egg sac (Fig.
Antennule and mouthparts as in previous species, but allobasis of antenna with one bipinnate abexopodal seta (Fig.
P1, P2, P3 and P4 (Fig.
Armature formula of P1−P4 as in Table
P5 (Figs
P6. Reduced to minute, rectangular protuberance, with one naked seta.
The length of the baseoendopodal setae of the female P5 is variable. The original description shows the lateral most seta as the longest (
This species has been found in many localities such as Wu-Li Lake (Kiangsu Province, China) (
In the present study, we found the species in Ta-pom swamp (southern Thailand, Krabi Province) in December 2016, water temperature was 26.27 °C, pH 6.74, salinity 0.27 ppt, conductivity 571 µS cm-1, and dissolved oxygen 4.32 mg L-1.
1 | Exopod of P5 with four setae | 2 |
– | Exopod of P5 with three setae | 4 |
2 | Exopod of antenna with one seta | O. anomalus (Ranga Reddy, 1984) |
– | Exopod of antenna with four setae | 3 |
3 | Cephalothorax with internal sausage-like structure | O. satunensis sp. n. |
– | Cephalothorax without internal sausage-like structure | O. tratensis sp. n. |
4 | P4 exp-3 without inner seta | O. besnardi Jakobi, 1954 |
– | P4 exp-3 with inner seta | 5 |
5 | Exopod of P5 fused to baseoendopod | O. bengalensis (Sewell, 1934) |
– | Exopod and baseoendopod of P5 completely separated | 6 |
6 | Baseoendopodal lobe with two setae | O. vitiospinulosa (Shen & Tai, 1963) |
– | Baseoendopodal lobe with three setae | 7 |
7 | Antenna without abexpodal seta on allobasis | O. taifensis Kikuchi, Daiand & Itô, 1993 |
– | Antenna with abexpodal seta on allobasis | 8 |
8 | P4 exp-3 with two outer spines | 9 |
– | P4 exp-3 with three outer spines | O. mohammed (Blanchard & Richard, 1891) |
9 | Caudal rami 2.8 times as long as wide, genital field with rows of spinules near P6 | O. krusensterni Schizas & Shirley, 1994 |
– | Caudal rami twice as long as wide, genital field without rows of spinules near P6 | O. fratrisaustralis Gómez, 2001 |
1 | Exopod of P5 with three setae | 2 |
– | Exopod of P5 with two setae | 4 |
2 | Exopod of antenna with one seta | O. anomalus (Ranga Reddy, 1984) |
– | Exopod of antenna with four setae | 3 |
3 | Cephalothorax with internal sausage-like structure | O. satunensis sp. n. |
– | Cephalothorax without internal sausage-like structure | O. tratensis sp. n. |
4 | P4 exp-3 without inner seta | O. besnardi Jakobi, 1954 |
– | P4 exp-3 with inner seta | 5 |
5 | Caudal rami more than four times as long as wide | O. bengalensis (Sewell, 1934) |
– | Caudal rami less than or approximately three times as long as wide | 6 |
6 | Antenna without abexpodal seta on allobasis | O. taifensis Kikuchi, Daiand & Itô, 1993 |
– | Antenna with abexpodal seta on allobasis | 7 |
7 | P4 exp-3 with two outer spines | O. krusensterni Schizas & Shirley, 1994 |
– | P4 exp-3 with three outer spines | 8 |
8 | Inner seta on P6 approximately or less than twice as long as outer seta | O. mohammed (Blanchard & Richard, 1891) |
– | Inner seta on P6 approximately or more than 2.5 times as long as outer seta | O. vitiospinulosa (Shen & Tai, 1963) |
The two new species identified in this study can confidently be assigned to the genus Onychocamptus based on the combination of characteristics mentioned by
When compared to the representatives of Onychocamptus, the two new species share the highest similarity with the Indian species O. anomalus, and the following features were common to all species: absence of the abexopodal seta on antenna, P4 exp-3 with only two outer spines, and four and three setae on the exopod of P5 of the female and the male respectively (Table
With the description of the two new species and new records of the two species from Thailand, the number of Onychocamptus species recorded in Thailand has now increased from one to five. Sampling of cave-dwelling copepods in this country has revealed a large number of new species of the genera Elaphoidella, Bryocyclops, Fierscyclops, and Thermocyclops (
Based on previous studies on cave-dwelling copepods in more than twenty caves in other regions of the country (
This research was financial supported by the Office of the Higher Education Commission, Thailand (2558A13562002), Center of Excellence on Biodiversity (BDC), Office of Higher Education Commission (BDC-PG2-161004) and Kasetsart University Research and Development Institute (KURDI), Kasetsart University.