Hatschekia triannuli, Uyeno, Daisuke & Nagasawa, Kazuya, 2012

Uyeno, Daisuke & Nagasawa, Kazuya, 2012, Two new species of the copepod Hatschekia Poche, 1902 (Siphonostomatoida: Hatschekiidae) from angelfishes (Pisces: Perciformes: Pomacanthidae) collected during the KUMEJIMA 2009 Expedition *, Zootaxa 3367, pp. 49-59 : 50-53

Hatschekia triannuli n. sp.

( Figs. 1–14 )

Material examined. Holotype, female ( NSMT –Cr 21660), ex Centropyge heraldi Woods & Schultz ( Perciformes : Pomacanthidae ), off Torishima Islet (26°19ʹN, 126°44ʹE), Kumejima Island, the Ryukyu Islands, East China Sea, Japan. 12 November, 2009. Paratypes: 2 females ( NSMT –Cr 21661) and 1 female ( RUMF –ZC–1502), same collection data as the holotype.

Description of female holotype. Body ( Fig. 1 ) 1204 long, excluding caudal rami, on holotype. Cephalothorax ellipsoidal, shorter than wide (208 × 319), widest at middle; dorsal frame with partly lacking double-semicircle with posterior complete ring and lateral bar along posterior margin of cephalothorax. Trunk elongated, fusiform bearing posterolateral lobe, longer than wide (1010 × 370), widest anteriorly, narrower posteriorly. Urosome ( Fig. 2 ), excluding caudal rami, shorter than wide 25 × 60. Caudal ramus ( Fig. 2 ) longer than wide 26 × 12, bearing 6 naked setae.

Rostrum ( Fig. 3 ) with 3 round processes along anterior margin and rostrum process. Antennule ( Fig. 4 ) indistinctly 5-segmented, 107 long; armature formula: 8, 4, 4, 1, 13 + 1 aesthetasc. Antenna ( Fig. 5 ) 3-segmented; proximal segment (coxa) unarmed; middle segment (basis) ornamented with surface pits; terminal claw unarmed; proximal segment length 34; middle segment length 157; terminal claw length 24; total length 215. Parabasal papilla absent. Oral cone robust. Mandible ( Fig. 6 ) slender, with sharp tip. Maxillule ( Fig. 7 ) bilobate; both lobes armed with 2 tapering elements. Maxilla ( Fig. 8 ) 4-segmented; proximal segment unarmed; second segment rodlike, with 1 basal seta; third segment elongate, with 1 distal seta; terminal segment small, bifid claw, presence of additional seta on terminal claw uncertain. Maxilliped absent.

Legs 1 and 2 ( Figs 9–10 ) biramous; both rami 2–segmented, except for 1-segmented endopod of leg 2; leg armature formula as follows:

Leg 1 ( Fig. 9 ) 93 long; protopod length 48; exopod length 21 similar to endopod length 24. Leg 2 ( Fig. 10 ) length 97; protopod length 60; exopod length 37; endopod length 29. Protopods and rami of leg 2 ornamented with rows of blunt spinules on posterior margin of anterior surface.

Intercoxal sclerite of legs 1 and 2 ( Figs 11–12 ) rod like, unarmed.

Leg 3 ( Fig. 13 ) represented by 2 simple setae on anterior 1/3 surface of trunk. Leg 4 ( Fig. 14 ) represented by 1 simple lateral seta on posterior 2/3 of trunk.

Variability of measurements. Paratype females share all important morphological characters with the holotype. Measurement range of their body parts and appendages of type series (n = 4) was as follows: body (excluding caudal rami) length 1204–1492 (1338 ± 118), cephalothorax length 200–208 (204 ± 4), cephalothorax width 319–343 (334 ± 10), trunk length 1010–1147 (1107 ± 65), trunk width 370–453 (396 ± 38), urosome length (excluding caudal rami) 21–41 (27 ± 9), urosome (excluding caudal rami) width 43–67 (58 ± 10), caudal ramus length 25–30 (28 ± 3), caudal ramus width 11–12 (11 ± 1), antennule length 103–114 (107 ± 5), antenna proximal segment length 18–34 (26 ± 6), antenna middle segment length 94–157 (128 ± 29), antenna terminal segment length 20–24 (22 ± 2), antenna total length 135–215 (176 ± 36), leg 1 length 93–112 (101 ± 8), leg 1 protopod length 48–52 (49 ± 2), leg 1 exopod length 21–30 (26 ± 4), leg 1 endopod length 24–29 (26 ± 3), leg 2 length 97–107 (100 ± 5), leg 2 protopod length 58–62 (60 ± 2), leg 2 exopod length 37–46 (39 ± 4), leg 2 endopod length 29–40 (36 ± 5).

Attachment site. Gill filaments.

Remarks. Among its congeners Hatschekia triannuli n. sp. shares a posterior ring at the dorsal frame of the cephalothorax with H. monacanthi Yamaguti, 1939 , and H. khahajya Uyeno & Nagasawa, 2010 . Hatschekia triannuli n. sp. differs from these 2 species in the following chareacters: the presence of a vertical bar with a short horizontal bar on the anterior tip of the dorsal frame, the presence of 2 to 3 apical teeth on the mandible, and the possession of 4 processes at the intercoxal sclerites of legs 1 and 2 (vs. dorsal frame with partly lacking doublesemicircle on anterior part; the mandible bearing only apical tip; the intercoxal sclerites of legs 1 to 2 unarmed) ( Yamaguti 1939; Uyeno & Nagasawa 2009a, 2010b). Four species, H. crenata Hewitt, 1969 , H. nohu Villalba, 1986 , H. pacifica Cressey, 1970 , and H. pagellibogneravi (Hesse, 1878) have been insufficiently described or illustrated with respect to the dorsal frame on the cephalothorax. Hatschekia crenata differs from H. triannuli n. sp. by having the following two characters: complex crenate frontal margin and posterolateral lobe of the cephalothorax (vs. the frontal margin of cephalothorax with the rostrum representing three round processes in H. triannuli n. sp.); and the presence of a small, sub-acute posterolateral process on the abdomen (vs. no such structures on the abdomen in H. triannuli n. sp.). Hatschekia nohu is easily distinguishable from H. triannuli n. sp.

by an ellipsoidal trunk, which is widest in the middle, and lacking a posterolateral lobe. Hatschekia pacifica is separated from H. triannuli n. sp. by having a vermiform trunk. Hatschekia pagellibogneravei is demarcated from H. triannuli n. sp. by having the cephalothorax with a pointed conical protuberance on the posterior margin.

Etymology. The specific name of the new species, triannuli , is derived from an arbitrary combination of “tri-” and the noun “annuli” which refers to dorsal frame forming three rings on the cephalothorax.

Figures

FIGURES 1 – 8. Hatschekia triannuli n. sp., holotype female NSMT – Cr 21660. 1, habitus dorsal; 2, posterior part of trunk, dorsal; 3, rostrum, ventral, rp = rostrum process; 4, right antennule, posterior; 5, left antenna, anterior; 6, mandible; 7, right maxillule, posterior; 8, left maxilla, posterior. Scales: 1 = 300 μm; 2, 5, 8 = 50 μm; 3 = 30 μm; 4 = 20 μm; 6 = 5 μm; 7 = 10 μm.

FIGURES 9 – 14. Hatschekia triannuli n. sp., holotype female NSMT – Cr 21660. 9, right leg 1, anterior; 10, right leg 2, anterior; 12, intercoxal sclerite of leg 1, anterior; 13, intercoxal sclerite of leg 2, anterior; 14, right leg 3, ventral; 15, right leg 4, ventral. Scales: 9 – 12 = 20 μm; 13, 14 = 5 μm.