Descriptions of two new species of the genus Copidognathus and females of Copidognathus jejuensis (Acari: Halacaridae) from Korea

Two new species of marine Halacaridae, namely Copidognathus quadriporosus and C. tetrarhachis, are described from South Korea. Copidognathus quadriporosus n. sp. is closely allied with C. brevipes Viets and C. tabellio (Trouessart), but differs from them in having four porose areas on AE. Copidognathus tetrarhachis n. sp. is closely related to C. ficipacus Bartsch and C. vulgaris Bartsch. Dissimilarities among them are discussed. Females of C. jejuensis are described for the first time and illustrated with SEM.

30 min, rinsed with freshwater for osmotic shock, and then fixed and stored in 80% ethanol.
Halacarids were cleared in lactic acid and mounted in glycerine jelly. Drawings were prepared using a camera lucida under a differential interference contrast microscope with Nomarski optics.
Materials for scanning electron microscopy were prefixed overnight at 4uC in 2.5% glutaraldehyde, then followed by post-fixation in 2% cold osmium tetraoxide. After dehydration through a graded series of ethanol (50-100% at 10% intervals) for 30 min each, the material was critical-point dried, and coated with gold-palladium in a high evaporator, and then examined with a scanning electron microscope (Hitachi S-520) operated at 20 kV.
Type specimens are deposited in the Department of Biology, Daegu University, Korea.

Holotype male
All dorsal plates separate. Idiosoma ( Figure 1A) 337 mm long, 208 mm wide. Areolae and costae on dorsal plates with rosette pores, remainder of AD, OC, and PD plates foveate ( Figure 1C). AD 108 mm long and 77 mm wide, anteriorly with small protuberance ( Figure 1A); anterior areola with about 10 rosette pores, paired posterior areolae with 10-13 rosette pores each. Paired ds 1 anterior to posterior areolae on AD; pair of gland pores near anterolateral margin on AD. OC 89 mm long, 54 mm wide; length to width ratio about 1.6; each with two corneae; areolae with rosette pores medial to corneae and posterolateral to posterior cornea; gland  pore lateral to posterior cornea adjacent to lateral margin of OC; pore canaliculus present nearly on lateral margin of OC; ds 2 located at anteromedial corner of OC. Brownish pigment found on upper cuticular layer near corneal zone. An elevated bar present laterally from middle to posterior side of OC.
PD 192 mm long, 135 mm wide; paired costae two to three rosette pores wide; anterior end of costa surpassing ds 3 but not reaching anterior end of PD; ds 3 -ds 5 on PD; distance from ds 3 to ds 4 53 mm and ds 4 to ds 5 55 mm; gland pore lateral to costae between ds 4 and ds 5 ( Figure 1A).
All ventral plates separate ( Figure 1B). AE 98 mm long, 184 mm wide. AE with three pairs of setae and a pair of epimeral pores. Epimeral processes I-II well developed, coxal origin. Paired ventrolateral areolae containing rosette pores between insertions of legs I and II. AE with four porose areas of canaliculi in groups, located below anterior seta on AE, and between lateral and posterior setae on AE. Each PE with three ventral setae and one dorsal seta.
GA 168 mm long, 117 mm wide ( Figure 1B). GO 44 mm long, 24 mm wide. Distance between anterior end of GO to that of GA 84 mm, about 1.9 times GO length; distance between posterior margin of GO to that of GA 36 mm. Spermatopositor large, reaching 58 mm anteriorly from anterior margin of GO and 29 mm apart from anterior margin of GA. Paragenital areolae well developed; 29 PGS, anterior PGS 24 mm apart from anterior margin of GO. Four pairs of SGS present.
Gnathosoma ( Figure 1D) 121 mm long, 70 mm wide. Palp consisting of four segments. Rostrum elongate, extending up to proximal setae of P 4 . P 1 and P 3 devoid of any seta, P 2 with one dorsal seta distally, P 4 with three long proximal setae, one minute distal seta. Proto-and deutorostral setae situated at tip of rostrum; tritorostral setae (long maxillary setae of rostrum) located just above middle of rostrum; gnathosomal base with a pair of setae (basirostral seta); distance between tritorostral seta and tip of rostrum 34 mm; distance between tritorostral seta and basirostral seta 49 mm. Gnathosomal base dorsally panelled, ventrolaterally porose. Rostral sulcus long, extending a little behind tritorostral setae. Tectum triangular.

Female
Idiosoma 342 mm long. Costae two rosette pores wide, anterior end of costa not reaching ds 3 . GA 169 mm long, 125 mm wide ( Figure 1E). GO 70 mm long; paragenital areolae well developed; ovipositor surpassing anteriorly 40 mm of GO, extending beyond anterior PGS. Distance between anterior end of GO to that of GA 85 mm, about 1.2 times GO length. Three pairs of PGS present; anterior pair 27 mm away from anterior end of GO and 55 mm away from anterior margin of GA; middle pair near the level of anterior margin of GO; third pair near posterior side of GO. Pair of SGS located at anterior sixth of GO.

Variability
Morphological variation was examined between the holotype and other specimens. In the holotype and in a female, costae on PD are two to three rosette pores wide and the anterior end of costa extends beyond ds 3 , while in other specimens, costae are one to two rosette pores wide, and anterior ends do not reach up to ds 3 . Anterior areola on AD contains about 10 rosette pores in the holotype, while from five to 10 rosette pores in other specimens according to individuals. Number of PGS in male ranges from 25 to 29. Rudimentary lamellae on ventral side of tibiae I and II are not found in most of the specimens examined. In a few specimens, tectum is obtuse-angled triangular with a very small, spinose tip. In many specimens, ostia are not prominent in porose areolae on ventrolateral side of gnathosomal base.

Remarks
Copidognathus quadriporosus n. sp. is allied with C. tabellio (Trouessart, 1894) from the North Atlantic, Mediterranean and Black Sea (Trouessart 1894(Trouessart , 1901Viets 1940;André 1946;Bartsch 2001) and C. brevipes Viets, 1940 from the Mediterranean and Black Sea (Viets 1940;Bartsch 1975Bartsch , 2001Morselli and Mari 1985) in having the combination of the following characteristics: three areolae on AD; ds 1 ahead of posterior areolae on AD; pair of gland pores located anterolaterally on AD; ds 2 located at anteromedial corner of OC; ds 3-5 present on PD; PD with two costae containing rosette pores; gland pores situating between ds 4 and ds 5 lateral to costa on PD; epimeral processes I-II well developed, and coxal origin; one pair of basirostral setae present; trochanters III and IV with distomedial process; telofemora III-IV with 0-1 ventral seta; pectinate setae on tibiae I-IV 2-2-1-0; tarsi III-IV with 4-3 dorsal setae. However, C. quadriporosus is distinguished from C. brevipes and C. tabellio by four porose areas on AE. Moreover, C. tabellio has brownish pigmentation anteriorly on AD and posteriorly on OC. Copidognathus brevipes is characterized by its short telofemora.
Copidognathus lamelloides Bartsch, 2000 from Europe (Bartsch 2000(Bartsch , 2001 looks somewhat similar to the present new species, but differs in many ways. Gland pores on AD are apart from each other in C. lamelloides. Setae ds 2 are located on membranous cuticle between OC and AD in C. lamelloides, while at anteromedial corner of OC in C. quadriporosus. One of the ventral setae on tibia IV is pectinate in C. lamelloides, while all ventral setae on the segment are smooth in C. quadriporosus. Copidognathus bavayi (Trouessart, 1896) known from Vietnam, Malaysia (Trouessart 1896, André 1937, Bartsch 1993) looks similar in general appearance to the present new species, but is distinguished from C. quadriporosus on the following points: C. bavayi has four dorsal setae on tarsus IV, while C. quadriporosus has three dorsal setae in that segment; brownish pigmentation is found on posterior portion of OC and anterior part of PD in C. bavayi, while such pigmentation is absent in the present species.
Both C. quadratus Makarova, 1972 andC. globulosus Makarova, 1975 recorded from the Kuril Islands (Makarova 1972(Makarova , 1975, adjacent to the type locality of the present species, are not allied with C. quadriporosus. Copidognathus quadratus differs from C. quadriporosus by the location of ds 3 (present on membranous cuticle in C. quadratus, while on PD in C. quadriporosus), the number of costae on PD (four costae in C. quadratus, while two costae in C. quadriporosus). Moreover, C. quadratus has anterior pair of PGS in female near the anterior margin of GA, while away from the anterior margin of GA in C. quadriporosus. Copidognathus globulosus is distinguished from C. quadriporosus by the number of costae on PD (four costae in C. globulosus, while two costae in C. quadriporosus), the length of rostrum (rostrum elongate, extending near the proximal setae of P 4 in C. quadriporosus, while near the anterior end of P 2 in C. globulosus). Moreover, areolae on GA present lateral to GO in C. quadriporosus, while areolae on GA located lateral to GO and also on anterolateral side of GA in C. globulosus (cf. Makarova 1975, Figure 3J).

Etymology
The proposed specific name is taken from the characteristic of ''four porose areas on AE''.

Holotype female
All dorsal plates separate ( Figure 3A). Holotype 326 mm long, 221 mm wide. Porose areolae and costae on dorsal plates with modified rosette pores, i.e. pits (panels) each with 3-13 canaliculi. AD 83 mm long, 88 mm wide, anteriorly with small protuberance. Three porose areolae on AD; anterior areola with 20-22 modified rosette pores, two oblong posterior areolae each with about 13-16 modified rosette pores; posterior areolae joining with anterior one, forming inverted ''Y''-shaped areolae. Paired ds 1 situated at joint of three areolae on AD, inserted close to each other; pair of gland pores near lateral margin on AD above level of ds 1 ; setae ds 2 located on membranous cuticle above anterior margin of OC. OC triangular, 59 mm long, 39 mm wide, length to width ratio about 1.5; with two corneae, posterior cornea faintly subdivided, porose areola on corneal zone; gland pore lateral to posterior cornea.
PD 133 mm long, 83 mm wide; with four costae; middle costae three panels wide; lateral costae one to two panels wide; lateral costa adjoining to lateral margin of PD. Dorsal setae of ds 3 -ds 5 present on PD.
All ventral plates separate ( Figure 3B). Setae on ventral plates longer than dorsal plates. AE 105 mm long, 194 mm wide; porose, canaliculi arranged in groups. AE with three pairs of setae and a pair of epimeral pores. Posterior margin of AE arched. PE with three ventral setae and one dorsal seta. GA 117 mm long, 102 mm wide; GO 71 mm long, 35 mm wide.  Ovipositor surpassing 21 mm from anterior margin of GO, distance between anterior margin of ovipositor to anterior margin of GA 8 mm. Distance between anterior margin of GO to that of GA 29 mm, about 0.4 times length of GO. Three pairs of PGS present; anterior pair near anterior margin of GA; middle pair below level of anterior margin of GO, third pair near posterior side of GO. Pair of SGS located at anterior sixth of GO.
Gnathosoma ( Figure 3D) 108 mm long, 82 mm wide. Palp consisting of four segments. P 1 and P 3 devoid of any seta, P 2 with one dorsal seta distally, P 4 with three long proximal setae and one minute distal seta. Tip of rostrum extending near end of P 2 . Proto-and deutorostral setae situated at tip of rostrum, tritorostral setae (long maxillary setae of rostrum) located on anterior half of rostrum, gnathosomal base with two pairs of setae (basirostral setae). Ventrolateral side of gnathosomal base porose. Tectum truncate.

Allotype male
Idiosoma 315 mm long. GA 144 mm long, 108 mm wide ( Figure 3C). GO 47 mm long, 24 mm wide, surrounded by 17 PGS; distance between anterior end of GO to that of GA 54 mm, about 1.1 times of GO length. Four pairs of SGS present, first, second and fourth pairs thin, while third pair thick and spur-like ( Figure 3C). Gnathosomal base with two pairs of setae (basirostral setae).

Variability
Idiosoma length ranges from 320 to 350 mm in five females examined and from 313 to 320 mm in four males. Number of PGS in four male specimens examined ranges from 17 to 21.

Remarks
In having the characteristics of three porose areolae fused to each other to form an inverted-''Y'' on AD, triangular OC, ds 1 closed to each other, gnathosoma with two pairs of basirostral setae, telofemora I and II with ventral porose area, tibia I with a small blunt spinose seta, and tibiae II-IV with 2-1-1 arrangement of pectinate seta, Copidognathus tetrarhachis n. sp. should be designated as a member of the C. pulcher group (cf. Bartsch 1984Bartsch , 1998. Among the congeners of this species group, the present species is closely related to C. ficipacus Bartsch, 1992 from Moorea Bora Bora, Society Islands (Bartsch 1992) and C. vulgaris Bartsch, 1998 from Rottnest Island, western Australia (Bartsch 1998) in sharing large GO in female and ovipositor little apart from anterior margin of GA. However, C. tetrarhachis differs from them as follows: there are four costae on PD in C. tetrarhachis, while two costae in C. ficipacus and C. vulgaris; length to width ratio of OC about 1.5 in C. tetrarhachis, while 1.9-2.0 in C. ficipacus and C. vulgaris; anterior areola on AD is relatively wider in C. ficipacus (cf. Bartsch 1998, Figure 4G); anterior margin of GA is rounded in female of C. ficipacus, while truncated in C. tetrarhachis; male has five to seven pairs of maxillary setae on gnathosomal base in C. vulgaris, while two pairs in C. tetrarhachis. Moreover, C. tetrarhachis has modified rosette pores on areolae and costae of dorsal plates, while simple porose panels in C. ficipacus and C. vulgaris.
Two species of Copidognathus pulcher group have been recorded from adjacent area, namely C. manicatus (Trouessart, 1899) from Cochinchina (South Vietnam) (Trouessart 1899;André 1937) and C. uniscutatus Bartsch, 1984from Mactan Island, Cebu, the Philippines (Bartsch 1984. There are four costae on PD in C. tetrarhachis, while two costae in C. manicatus; female GO relatively larger in C. tetrarhachis, and the distance between anterior margin of female GO and that of GA is about 0.4 of GO length in C. tetrarhachis, while about 0.85 of GO length in C. manicatus (cf. André 1937, Figure 2v). Copidognathus uniscutatus Bartsch is easily distinguished from C. tetrarhachis by having fused dorsal plates.
In C. magnipalpus (Police, 1909) of the C. pulcher group, the lateral costae are known to vary from absent to almost half the length of the middle costae (Bartsch 1975(Bartsch , 2001). In C. tetrarhachis, the two lateral costae on PD apparently and consistently exist without such length variation throughout all materials examined. It needs further investigation to know whether such variability might exist in other species, too. So, for the specific determination, other characters along with lateral costae should be taken into consideration.

Etymology
The proposed specific name tetrarhachis (tetra, Gr. four; rhachis, Gr. ridge or rib on the back) alludes to the ''four costae'' on PD, one of the discriminative characteristics from the related species.

Female
Idiosoma 334-360 mm long. AD 107 mm long, 85 mm wide. OC 90 mm long, 43 mm wide (length to width ratio about 2.1) in one side, while 87 mm long, 44 mm wide (length to width ratio about 2.0) in other side. PD 129 mm long, 103 mm wide. PD truncate anteriorly.
Posterior margin of AE arched. GA 156 mm long, 113 mm wide. GO 59 mm long, 27 mm wide. Ovipositor small going 13 mm anteriorly from the anterior margin of GO. Distance between anterior margin of GO to that of GA 70 mm, about 1.2 times length of GO. Three pairs of PGS present, first pair anterior to GO, second pair below the level of anterior margin of GO, third pair beside posterior part of GO ( Figure 5D). One pair of SGS present.
Rostrum tip almost reaching distodorsal end of P 2 ( Figure 5C). Rostral sulcus long, extending beyond tritorostral setae posteriorly. Telofemora I and II with ventromedial and ventrolateral lamellae. Lateral edge of ventrolateral lamella on telofemur I uneven. Telofemora III and IV with large ventrodistal and smaller distal lamellae. All patella and tibiae with distoventral and distal lamellae. Tibiae I and II each with two denticulate processes proximoventrally ( Figure 5E, F). Tarsus III with four dorsal setae and two smooth PAS, while tarsus IV with three dorsal setae and two plumose PAS. Two anterior dorsal setae on tarsi III and IV plumose in nature that are clearly found under SEM study. Lateral claws with accessory process dorsally and pectinate ventrally. Lateral claws of leg I consist of less tines than in claws of legs II-IV. Lateral claws of legs II-IV with about 17-20 tines ( Figure 5G, H).

Variability
Edge of ventrolateral lamella of telofemur I varies from slight to very uneven and in some specimens almost serrated. In some specimens ventrolateral lamellar edge of telofemur II is also uneven. Length to width ratio of OC varies from 1.8 to 2.1. Posterior tip of OC varies slightly among individuals: in some specimens it is slightly blunt while in others more pointed, in some specimens this variation is even found in right and left side of OC also. Length of rostral sulcus varied from 0.65 to 0.74. The position of tritorostral setae ranged from 0.45 to 0.53 of rostrum length from the tip of rostrum.

Remarks
The male of Copidognathus jejuensis Chatterjee and Chang was earlier recorded from Jejudo Island, Korea (Chatterjee and Chang 2004a). The female of this species is recorded here for the first time. SEM structure of male tarsus IV shows two plumose PAS. Female tarsus IV also shows similar plumose PAS. There is no sexual dimorphism found on PAS in this species.