Copidognathus tetrarhachis, Chatterjee & Chang, 2006

Chatterjee, Tapas & Chang, Cheon Young, 2006, Descriptions of two new species of the genus Copidognathus and females of Copidognathus jejuensis (Acari: Halacaridae) from Korea, Journal of Natural History 40 (29 - 31), pp. 1761-1774 : 1767-1771

Copidognathus tetrarhachis new species

( Figures 3 , 4 )

Material examined

Holotype: female (DB00037), among coralline algae, Jocheon (33 ° 329540N, 126 ° 389250E), Jeju Island, South Korea, 25 January 2003 (C. Y. Chang and J. M. Lee) . Paratypes: one female (DB00038), one male (allotype, DB00039), collection data same as holotype . Additional materials: three males, three females, collection data same as holotype .

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.

Chaetotaxy of legs ( Figure 4A–D ): trochanter 1-1-1-0; basifemur 2-2-2-2; telofemur 5-5- 2-2; patella 4-4-3-3; tibia 7-7-5-5; tarsus (PAS excluded) 7-4-3-3. Arrangement of pectinate setae on tibiae I–IV: 1-2-1-1. Telofemora I and II with ventral areola containing canaliculi. Tarsus I with three dorsal setae, one solenidion, three ventral setae, two doublets eupathid PAS. Tarsus II with three dorsal setae, one solenidion, two doublets eupathid PAS. Tarsi III and IV with three dorsal setae. All legs with two lateral claws and a bidentate median claw. Lateral claws with accessory process dorsally, pectinate ventrally.

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 1984, 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, 1984 from 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, 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.

Figures

Figure 2. Copidognathus quadriporosus n. sp., male. (A–D) Legs I–IV. Scale bar: 20 mm.

Figure 3. Copidognathus tetrarhachis n. sp. (A, B, D) Female; (C) male. (A) Idiosoma, dorsal; (B) idiosoma ventral; (C) idiosoma ventral; (D) gnathosoma. Scale bars: 50 mm.

Figure 4. Copidognathus tetrarhachis n. sp., female. (A–D) Legs I–IV. Scale bar: 50 mm.