Sladenia Regan (1908) is a genus of lophiid anglerfish with rounded rather than depressed head, and compressed rather than depressed tail; nasal sacs not constricted at the base; very long pseudobranchia; humeral, subopercular, quadrate, parietal and articular spines absent; epiotic and interopercular spines low and rounded ; vomerine teeth larger than palatine teeth; illicial bone and second dorsal spine inserting very close together on illicial pterygiophore; third or third and fourth dorsal spines invisible, hiding under the skin of post-cephalic portion; and smooth ridge on frontal bones anterior to eyes and lateral to illicial pterygiophore.
There were only four specimens, identified as 3 species, i. e., S. gardineri Regan, 1908, S. remiger Smith et Radcliffe 1912 and S. shaefersi Caruso et Bullis 1976, belonging to the genusSladenia in the world before 1976. During the period from 1980 to 1982, the RV “ Dongfang” and the RV “Nanfeng” of the East China Sea Fisheries Institute and the South China Sea Fisheries Research Institute respectively, completed a survey of the deep water fish fauna of the East and South China Seas. Four separate Chinese specimens of the rare lophiid anglerfish genus Sladenia were collected. With detailed analysis of the four rare specimens, it was recognized that they should belong to the same species, and also a new species named as Sladenia zhui.
Sladenia zhui Ni, Wu et Li, sp. nov. (Figs 1-3)
Materials and methods. Terminology used in describing the angling apparatus follows Bradbury (1967) and Caruso (1981); counting and measurements follow Caruso and Bullis (1976).Table 1 shows the collecting information and depositing sites of 4 specimens of Sladenia zhui sp. nov.
Synonym. Sladenia remiger: Ni (nec Smith et Radcliffe, 1912), l988: 317-318, fig. 250, two female specimens, 500-525 mm
SL, East China Sea, depth 979m.
Sladenia gardineri: Su (nec Regan, 1908), 2002: 351-352, fig. 163, four specimens, 210-525mm SL, deep waters of the East China Sea and the South China Sea.
Counts and measurements. D. IV-9-10; A. 6-7; P. 18-19; V. I-5; C. 8 (outer two elements unbranched , other branched)．Measurements in percentage of standard length (SL): head length (HL) 37.9-41.5, head width (HW) 20.0-25.6, head depth (HD) 30.7-35.7; snout length (SNL) 17.1-19.7, snout width (SNW) 11.7-13.1 , length of illicial bone (1st dorsal spine) 35-41, length of 2nd dorsal spine 10.6-20.2. Measurements in percentage of head length (HL): head width (HW) 50.0-64.3, snout length (SNL) 44.0-49.2 , snout width (SNW) 29.2-34.6 (Tables 2 and 3).
Description. Head rounded, body compressed; cranial spines sturdy and blunt, frontal and sphenotic bones are slightly produced; pronounced muscular hump immediately behind head; illicial bone longer (35%-41% of SL) and slender, second dorsal spine also slender, approximately 1/3-1/2 length of illicial bone;the fifth and sixth dorsal spines absent, the third or third and fourth present but contained in loose fold of skin; skin bearing numerous small, lanceolate cirri arranged in irregular rows and patches on head, lower jaw and caudal peduncle, but confined generally to region of lateral line on body; color pattern in formalin uniform brown, the terminals of all fins are blackish; inside of mouth dusky; peritoneum black; teeth typically cardiform but proportionally smaller than those of other lophiids.
Diagnosis. Sladenia zhuiis distinguished from other members of its genus by having a much wider snout (11.7%-13.1% of SL; 29.2%-34.6% of HL); by the presence of four dorsal spines, the first and second close to the tip of snout, the third and fourth completely contained within loose fold of skin which connects these two spines to the soft dorsal fin; by the blunt, sturdy cranial spines; and by having a uniform brown coloration, lacking vermiculations or contrasting pigment.
Discussion. The four Chinese specimens were identified as S. remiger Smith et Radicliffe by Ni (1988) and S. gardineri Regan by Su (2002). In fact, the four specimens have significant differences from the above two species (for detail, refer to the following key). Therefore, we thought it should be a new species in 2000 and posted the manuscript with figures of the specimens to Dr. J. H. Caruso of Tulane University, USA, a specialist in deep sea lophiid anglerfish. He also agreed it should be a new species. The four species of the Sladenia can be distinguished by the following key.
Key to the world species of the genus Sladenia Regan, 1908
1(4) Post-cephalic portion of spinous dorsal fin consisting of one embedded spine and hiding under the skin
2(3) Having a intermediate head length (32.7%-34.8% of SL); moderate snout length (47.5%-57.1% of HL);one post-cephalic dorsal spine completely embedded in subcuneus tissue and not contained in loose fold of skin; low, rounded cranial spine; a color pattern consisting of relatively coarse, irregular, light vermiculations over a brown background covering the dorsal and lateral surface of the head and body, and dorsal, anal, caudal and pectoral fins (two specimens, 146.2-397.0 mm SL; Western Atlantic Ocean: Caribbean Sea, depth 850-1200m)……………………………………………..S. shaefersi Caruso et Bulli, 1976
3(2) Having a shorter head (27.6% of SL); longer snout length (74.1% of HL); One post-cephalic dorsal spine almost completely contained within loose fold of skin which connects it to the soft dorsal; well developed cranial spine, with the frontal and sphenotic spine enlarged, the former greatly; and a unform pale gray coloration,lacking vermiculations or other contrasting pigment ( single specimen, 92.3 mm SL; South-Western Pacific Ocean: Gulf of Tomini, Celebes, depth 1294m).…………….Ｓ. remiger Smith et Radcliffe, 1912
4 (1) Post-cephalic portion of spinous dorsal fin consisting of two spines contained in a loose fold of skin, and connects it to the soft dorsal
5 (6)Having a narrower snout (8.8% of SL, 21.3% HL); low, sharply pointed cranial spines; and a color pattern of relatively fine, irregular, pale vermiculations on a darker background (single specimen, 351 mm SL, Indian Ocean, Chagos Archipelago, Solomon Island, depth 900 m)……………………………………………………………S. gardineri Regan, 1908
6(5) Having a much wider snour (11.7%-13.1% of SL, 29.2%-34.6% of HL); blunt sturdy cranial spines; and a uniform brown coloration , without vermiculations or other contrasting pigment(four specimes,210-525 mm SL, Western Pacific Ocean: the EastChina Sea and the South China Sea, depth 655-979m)…………….S. zhui, sp. nov.
Etymology. We take pleasure in naming this species in honor of Prof. ZHU Yuan-Ding (CHU Yuan-Ting),the former president of the Shanghai Ocean University and director of the East China Sea Fisheries Research Institute, in recognition of his outstanding contributions to fisheries education and science, especially to ichthyology of China.
Acknowledgments We wish to express our sincere gratitude to Dr. John H Caruso of Tulane University, New Orleans, Louisiana, U.S.A. and Dr. Theodere W. Pietsch, School of Fisheries, College of Ocean and Fisheries Science, University of Washington, U.S.A. for providing valuable references on the genus Sladenia and kind suggestions. We also thank Mr. Lü Shaoping of the East China Sea Fisheries Research Institute for his illustration in this paper.