A new family of poecilostomatoid copepods (Strepidae fam. nov.) associated with the sun coral, Tubastraea coccinea Lesson, 1829 in Taiwan Author Cheng, Yu-Rong Author Liu, Shang-Yin Vanson Author Dai, Chang-Feng text Zootaxa 2016 4174 1 346 354 journal article 10.11646/zootaxa.4174.1.21 79324c77-0f24-479e-8783-45f7e2cf7c56 1175-5326 160182 58592E7C-2616-456B-B619-1CEA2EFDEF81 Strepus elongatus gen. et sp. nov. ( Figs. 1–2 ) Type locality. Taiwan , north coast; off Yaliu ( 25°12.307’N , 121°41.380’E ), northwest of Keelung ; washings of Tubastraea coccinea Lesson, 1829 . Type material. A total of 31 copepods ( 9 ♀♀ , 24 ♂♂ ) were obtained from four localities in Taiwanese waters . Holotype ♀ (from type locality; NTUIO-CONF 0001), allotype ♂ (from type locality; NTUIO-CONF 0002) and remaining paratypes (NTUIO-CONF 0003) were deposited in the Institute of Oceanography , National Taiwan University, Taipei , Taiwan. Prevalence . 15% at Yaliu; 17.5% at Doufu–Cape; 5% at Tiaoshi; 0% at Wanlitong. Mean intensity . 1.5 at Yaliu; 3.1 at Doufu–Cape; 1.0 at Tiaoshi; 0 at Wanlitong. Mean abundance . 0.23 at Yaliu; 0.55 at Doufu–Cape; 0.05 at Tiaoshi; 0 at Wanlitong. Description of female. Body ( Fig. 1 A–B) elongate and cylindrical, measuring 2.74 (2.66–2.90) mm in total length and 0.80 (0.77–0.82) mm in greatest width, based on five specimens. Ratio of body length to greatest width 3.43:1. Segmentation of body distinct, but incomplete. Head ( Fig. 1 A–B) very small, distinctly set off from trunk. Urosome ( Fig. 1 C) 3-segmented, much shorter than prosome; genital and postgenital segments recurved upward in some specimens. Areas of attachment of egg sacs located dorso-laterally. Egg sac not observed. Caudal ramus ( Fig. 1 D) elongate, covered with denticles; bearing two terminal setae. Surface of body unornamented ( Fig. 1 A–B). Rostral area ( Fig. 1 E, G) distinctly protruded and covered with denticles. Antennule ( Fig. 1 E, G) 4-segmented; armature: 0, 3, 2, and 5 setae; all setae naked. Antenna ( Fig. 1 H) stronger and roughly, 3-segmented; basal and second segment unarmed and broad; distal segment with three small denticles. Labrum ( Fig. 1 E) elongate and swollen. Mandible ( Fig. 1 E–F, I) slender, with pointed blade fringed with teeth on distal side. Maxillule ( Fig. 1 E–F, J) a small lobe tipped with two long setae. Maxilla ( Figs. 1 E–F, 2A) 2- segmented; proximal segment large and unarmed; distal segment small, with a distal process fringed with spinules on outer side. Maxilliped ( Fig. 2 B) 2-segmented; first segment largest, with two spiniform inner setae; second segment tipped with two long setae and one denticle. Legs 1–5 absent. Description of the male. Body ( Fig. 2 C) generally as in female, but much more slender, with abdominal region arched upward. Length 2.20 (2.10–2.48) mm and greatest width 0.39 (0.37–0.41) mm, based on five specimens. Ratio of body length to greatest width 5.64:1. Caudal ramus elongate, shaped and armed as in female. Antennule, antenna, mandible, maxillule, maxilla, and maxilliped like those of female, but one additional aesthetasc present on second segment of antennule (at point indicated by a dot in Fig. 1 G). Legs 1–2 ( Fig. 2 D–E) a small unornamented free segment carrying two terminal setae. Legs 3–5 absent. Etymology . The species name is derived from the Latin elongatus , meaning “elongate”, and alludes to the slender body of the new species. Molecular analysis. A phylogenetic analysis using 18S rDNA sequence data was undertaken to determine the phylogenetic position of S . elongatus within the Copepoda, and to elucidate its phylogenetic relationships with the other families in the Poecilostomatoida ( Fig. 3 ). After trimming several indels, the final alignment set with total length of 1,662 bp was used to generate a Maximium Likelihood tree. Strepus elongatus gen. et sp. nov. was identified as a member of the Poecilostomatoida and sister of a clade including Xarifia sp. ( Xarifiidae ), Critomolgus sp. and Doridicola agilis (Rhynchomolgidae) , Anchimolgus sp. 1 and Anchimolgus sp. 2 ( Anchimolgidae ) in the ML tree with strong bootstrap support (100). The average distance between these species, which represent five families, is 0.028, while the distance between S . elongatus and those species is 0.064 ( Table 1 ). FIGURE 1. Strepus elongatus gen. et sp. nov. (female). A, habitus, dorsal; B, habitus, lateral; C, urosome; D, caudal ramus; E, cephalosome, ventral; F, cephalosome, lateral; G, rostrum and antennule (dot indicating position of aesthetasc in male); H, antenna; I, mandible; J, maxillule. A1 = antennule, A2 = antenna, MD = mandible, MX1 = maxillule, MX2 = maxilla, MXPD = maxilliped. Scale bars: A–B = 0.5 mm; C = 0.2 mm; D–E = 0.04 mm; F = 0.1 mm; G–J = 0.02 mm. FIGURE 2. Strepus elongatus gen. et sp. nov. (female, A–B; male, C–E). A, maxilla; B, maxilliped; C, habitus, lateral; D, leg 1; E, leg 2. Scale bars: A–B, D–E = 0.02 mm; C = 0.5 mm. TABLE 1. K2P genetic distance between Strepus elongatus gen. et sp. nov. and Sabelliphilus elongatus , Xarifia sp., Critomolgus sp., Doridicola agilis , Anchimolgus sp. 1 and Anchimolgus sp. 2 based on a 1,662 bp fragment of the 18S rRNA gene. Anchimolgus Anchimolgus Strepus Critomolgus Doridicola Sabelliphilus Xarifia sp. 1 sp. 2 elongatus sp. agilis elongatus sp. gen. et sp. nov. Anchimolgus sp. 1 Anchimolgus sp. 2 0.007 Strepus elongatus 0.062 0.063 gen. et sp. nov. Critomolgus sp. 0.019 0.014 0.062 Doridicola agilis 0.017 0.012 0.060 0.004 Sabelliphilus elongatus 0.060 0.057 0.073 0.058 0.056 Xarifia sp. 0.014 0.014 0.061 0.014 0.011 0.059