Three new species of the genera Loxoconcha and Xestoleberis (Crustacea, Ostracoda, Podocopida) from central and southern Vietnam Author Dung, Le Doan Author Tsukagoshi, Akira text Zootaxa 2018 2018-09-07 4472 1 111 126 journal article 29459 10.11646/zootaxa.4472.1.5 511164fa-b1f3-448a-9d01-9ff882d456c3 1175-5326 1440042 68A4616A-EC22-4A2D-A575-DCBD03BE119D Xestoleberis vietnamensis sp. nov. Type series. All specimens were collected at the coral reef in Dam Ngoai Island , Phu Quoc Marine Protected Area , Phu Quoc Island , southwest of Vietnam , 9°59'42"N , 104°02'17"E ( Fig. 1A,B ) in November 2014 . The substrate consisted mainly of very coarse sand, dead coral and algae. Holotype : SUM-CO-2429 (Soft parts and a right valve of adult male; soft parts were mounted on a glass slide using “Neo Shigaral” as mounting agent, and the carapace was mounted on a cardboard slide with single hole). Paratypes : 5 males (SUM-CO-2431, 2433, 2434, 2435, 2436) , 2 females (SUM-CO-2430, 2432); soft parts mounted on a glass slide and carapaces on a cardboard slide with single hole; other specimens (carapaces) are kept on a cardboard slide with single hole. Etymology. “From Vietnam ”: holotype specimen was collected from Dam Ngoai Island, Phu Quoc Marine Protected Area in Phu Quoc Island, Southwest of Vietnam . Diagnosis. Carapace inflated, subreniform to subovate in lateral view, showing sexual dimorphism in shape; dorsal margin rounded downward, ventral margin weakly sinuous as oral concavity. Posterior margin rounded in female, more angular in male. Living specimens white. Frontal muscle scar trefoil-Y-shaped. Four adductor muscle scars isolated, arranged in sub-vertical row, upper one U-shaped ( Fig. 6I ). “ Xestoleberis- spot” divided into two parts ( Fig. 6H ). Carapace consisting of two types of normal pores, lip-type ( Fig. 6M ) and sieve-type ( Fig. 6N ). Fourteen lip-type pores, while others are sieve-type pores. Male copulatory organ with subquadrate capsule, large distal lobes, left one terminating with small spine and right one rounded. Description. Carapace ( Fig. 6 ). Adult carapace size sexually dimorphic, males smaller than females ( Fig. 6A, B ). Carapace elongate-oval in dorsal view ( Fig. 6C, D ), with bluntly pointed anterior end, and narrowly rounded posterior end; almost circular to oval in posterior view ( Fig. 6G ). Hinge antimerodont ( Fig. 6K, L ) with welldeveloped teeth and sockets in anterior and posterior hinge elements. Median element strongly curved and finely crenulated. Frontal muscle scar trefoil-Y-shaped. Four adductor muscle scars isolated, arranged in sub-vertical row, upper one U-shaped ( Fig. 6I ). “ Xestoleberis- spot” strongly divided into two parts ( Fig. 6H ). Carapace consisting of two types of normal pores, lip-type ( Fig. 6M ) and sieve-type ( Fig. 6N ). Marginal pores funnel-type pore ( Fig. 6J ). Both sexes with 14 lip-type pores, while others are sieve-type pores. Antennula ( Fig. 7A ). Six articulated podomeres, length ratios from proximal to distal 25:24:7:13:1:6, width of podomeres decreasing in this order. First podomere elongated pentagonal without seta. Second podomere elongate rectangular with setulae along anterior-distal margin, 1 short simple apical seta at posterior corner. Third podomere small, short, trapezoidal with 1 hirsute apical seta at anterior corner. Fourth podomere elongated rectangularly with 1 hirsute seta on posterior distal end, 1 medium-length and 1 short hirsute apical seta at anterior corner. Fifth podomere elongated rectangularly with 1 long seta on posterior distal end, 1 long and 1 medium-length apical seta at anterior corner. Sixth podomere very small, rectangular with 1 medium-length aesthetasc “Ya,” and 1 short seta and 2 long setae on distal end. Antenna ( Fig. 7B ). Consisting of four articulated podomeres, length ratios from proximal to distal 30:12:30:5, width decreasing in this order. First podomere with very long stout two-joined exopodite (=spinneret seta) at anterior distal end. Second podomere trapezoidal with relatively long setules along proximal anterior margin and 1 hirsute seta on posterior-distal end. Third podomere elongated bearing relatively long setulae on proximal anterior margin, 1 short aesthetasc “Y” and 2 hirsute setae protruding from posterior, 2 simple setae from anterior edges at proximately mid-length, and 1 hirsute robust seta at apical posterior corner. Fourth podomere very short and small with 1 reduced seta and 2 stout and chelate setae on distal end. Mandibula ( Fig. 7C , C’). Five articulated podomeres. Coxa stout, bearing 6 teeth on medial edge and 1 seta on anterior margin. Basis bearing exopodite with 3 plumose setae, 1 simple seta at posterior corner and 1 hirsute seta at ventro-distal end. First podomere of endopodite bearing 1 hirsute seta antero-distally, 2 very long and 2 shorter hirsute setae ventrally. Second podomere of exopodite consisting of 4 apical setae at anterior corner, 1 apical seta at posterior-distal corner and 1 seta on distal end. Third podomere of exopodite with 2 simple setae and 1 claw-like seta at distal end. Maxillula ( Fig. 7D , D’). Exopodite a thin branchial plate, with 16 long plumose setae and 1 hirsute reflexed seta. Basal podomere bearing endopodite and 3 endites. Endopodite consisting 2 podomeres and bearing 4 hirsute setae at anterior distal end of first podomere, and 3 hook-shaped hirsute setae (1 seta very large and 2 setae smaller) on distal end, 1 simple seta on ventral distal end of second podomere. Three endites bearing 4, 5 and 4 hirsute setae on distal end, respectively. Third endite also consisting of long seta on ventral proximal margin, stout proximally with medium-length setulae. Fifth limb ( Fig. 7E ). Four articulated podomeres bearing terminal claw-like seta, length ratios from proximal to distal 15:10:5:6. First podomere with 1 short and 1 medium hirsute seta in middle of anterior margin, 1 long hirsute seta at one-fourth from posterior proximal end and 2 hirsute setae at anterior apical corner. Second podomere with setulae along anterior distal margin and 1 hirsute seta at anterior apical corner. Third and fourth podomeres with setulae along anterior distal margin and without seta. Sixth limb ( Fig. 7F ). Consisting of four articulated podomeres, terminating with claw-like seta, length ratios from proximal to distal 17:12:7:7. First podomere carrying 1 short and 1 medium hirsute seta in middle of anterior margin, 1 very long hirsute seta at one-fourth from posterior proximal end and 1 hirsute seta at anterior apical corner. Second podomere with setulae along anterior distal margin and 1 hirsute seta at anterior apical corner. Third and fourth podomeres with setulae along anterior distal margin and not bearing seta. Seventh limb ( Fig. 7G ). With four articulated podomeres, terminating with claw-like seta, length ratios from proximal to distal 11:11:4:6. First podomere carrying 1 short hirsute anterior margin seta at one-fourth and 1 long hirsute seta on anterior margin of one-third from proximal end, 1 long hirsute seta at one-fifth from posterior proximal end and 1 hirsute seta at anterior apical corner. Second podomere with setulae along anterior margin and 1 hirsute seta at anterior apical corner. Third and fourth podomeres with setulae along anterior distal margin and not carrying seta. Male copulatory organ ( Fig. 7H ). Basal capsule subquadrate. Distal lobes large and thin, distally asymmetrical; left lobe terminating like spine, right lobe with rounded tip. Ejaculatory duct conspicuous and terminating on distal lobe. Furca ( Fig. 7I ). With one long seta and two short hirsute setae, located on posterior distal ward of male copulatory organ. Brush-shaped organ ( Fig. 7J , J’). Y-shaped in general; consisting of pair of branches with approximately 26 fine setae on each distal margin. Dimensions. See Table 1 . Remarks. The carapace of Xestoleberis vietnamensis sp. nov. is highly similar to that of X. hanaii Ishizaki, 1968 ; X. sesokoensis Sato & Kamiya, 2007 ; and X. ryukyuensis Sato & Kamiya, 2007 . However, this species is smaller than X. hanaii and X. sesokoensis , but larger than X. ryukyuensis . The morphology of the male copulatory organ of this species is different from that of X. ryukyuensis , but similar to that of X. hanaii , X. porthedlandensis Hartmann-Schröder & Hartmann, 1978 , and X. sesokoensis . However, the copulatory duct of this species is question-mark shaped and thicker than that of X. hanaii and X. sesokoensis . The ratio of the length of the distal lobe to the length of the whole male copulatory organ of this species is smaller than that of X. hanaii . Furthermore, the distal lobes of the male copulatory organ of X. vietnamensis sp. nov species are more slender than those of both X. hanaii and X. porthedlandensis .