Xestoleberis munensis, Dung & Tsukagoshi, 2018

Dung, Le Doan & Tsukagoshi, Akira, 2018, Three new species of the genera Loxoconcha and Xestoleberis (Crustacea, Ostracoda, Podocopida) from central and southern Vietnam, Zootaxa 4472 (1), pp. 111-126 : 118-124

publication ID	https://doi.org/ 10.11646/zootaxa.4472.1.5
publication LSID	lsid:zoobank.org:pub:68A4616A-EC22-4A2D-A575-DCBD03BE119D
DOI	https://doi.org/10.5281/zenodo.5990673
persistent identifier	https://treatment.plazi.org/id/0382DE2A-FFF3-FFF7-50CE-4E61FC9EFA68
treatment provided by	Plazi
scientific name	Xestoleberis munensis
status	sp. nov.

Treatment

Xestoleberis munensis View in CoL sp. nov.

( Figs 8 View FIGURE 8 , 9 View FIGURE 9 )

Type series. All specimens were collected at Hon Mun Island , Nha Trang Marine Protected Area, Nha Trang Bay in Nha Trang City, central Vietnam, 12°10'08"N, 109°17'49"E ( Fig. 1A, C View FIGURE 1 ) in November 2014. The substrate consisted mainly of very coarse sand, dead coral and algae. Holotype: SUM-CO-2437 (soft parts and a right valve of adult male; soft parts are stored on a glass slide in “Neo Shigaral” as mounting agent and the carapace on a cardboard slide with single hole). Paratypes: 4 males (SUM-CO-2439, 2441, 2442, 2443) GoogleMaps , 2 females (SUM-CO- 2438, 2440); soft parts mounted on a glass slide in “Neo Shigaral” agent and carapaces on a cardboard slide with single hole; carapaces of other specimens are kept on a cardboard slide with single hole.

Etymology. Named after the type locality, Hon Mun Island, where this species was collected.

Diagnosis. Carapace inflated, subreniform to subovate in lateral view, showing sexual dimorphism in shape; dorsal margin evenly rounded, ventral margin weakly sinuous as oral concavity. Posterior margin rounded in female, more angular in male. Living specimens white. Frontal muscle scar Y/U-shaped. 4 adductor muscle scars isolated, arranged in sub-vertical row, upper one U-shaped ( Fig. 8I View FIGURE 8 ). “ Xestoleberis- spot” weakly divided into two parts ( Fig. 8H View FIGURE 8 ). Carapace consisting of two types of normal pores, lip-type ( Fig. 8M View FIGURE 8 ) and sieve-type ( Fig. 8N View FIGURE 8 ). Male copulatory organ with subquadrate capsule, large distal lobes, left one terminating with large spine, right one with tiny spine and with rounded tip.

Description. Carapace ( Fig. 8 View FIGURE 8 ). Size of adult carapace strongly sexually dimorphic, males smaller than females ( Fig. 8A, B View FIGURE 8 ). Carapace elongate-oval in dorsal view ( Fig. 8C,D View FIGURE 8 ), with bluntly pointed anterior end, and narrowly rounded posterior end; almost circular to suboval in posterior view ( Fig. 8G View FIGURE 8 ). Hinge antimerodont ( Fig. 8K, L View FIGURE 8 ) with well developed teeth and sockets in anterior and posterior hinge elements. Median element strongly curved and finely crenulated. Frontal muscle scar Y/U-shaped. 4 adductor muscle scars isolated, arranged in vertical row, upper one U-shaped ( Fig. 8I View FIGURE 8 ). “ Xestoleberis- spot” weakly divided into two parts ( Fig. 8H View FIGURE 8 ). Carapace with two types of normal pores, lip-type pore ( Fig. 8M View FIGURE 8 ) and sieve-type pore ( Fig. 8N View FIGURE 8 ). Marginal pores funnel-type pore ( Fig. 8J View FIGURE 8 ).

Antennula ( Fig. 9A View FIGURE 9 ). Consisting of six articulated podomeres, length ratios from proximal to distal 25:24:8:8:13:6, width of podomeres gradually decreasing in this order. First podomere large and pentagonal, bearing no seta. Second podomere elongated rectangular with setulae along middle of anterior margin and anterior distal margin, 1 short hirsute apical seta at posterior corner. Third podomere short, trapezoidal carrying 1 hirsute apical seta at anterior corner. Fourth podomere parallelogram-shaped bearing 1 hirsute seta on posterior distal end, 2 simple apical setae with unequal length at anterior corner. Fifth podomere rectangular with 1 long seta at posterior distal end, 2 long apical seta at anterior corner. Sixth podomere small, rectangular, bearing 1 short-length aesthetasc “Ya” and 1 short seta, 1 medium and 1 long seta on distal end.

Antenna ( Fig. 9B View FIGURE 9 ). Consisting of four articulated podomeres, length ratios from proximal to distal 27:10:30:5, 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 setulae along proximal anterior margin and 1 hirsute seta on posterior distal end. Third podomere elongated, bearing 1 short aesthetasc “Y” and 2 hirsute setae protruding from posterior edge, 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 on posterior distal end and 2 stout and chelate setae on distal end.

Mandibula ( Fig. 9C View FIGURE 9 , C’). With five articulated podomeres. Coxa stout, with approximately 10 teeth on medial edge and 1 short seta at anterior margin. Basis carrying exopodite with 3 plumose hirsute setae, 1 simple seta at posterior corner and 1 hirsute seta at ventral distal end. First podomere of endopodite consisting of 1 very long hirsute seta antero-distally, 2 long and 2 shorter hirsute setae ventrally. Second podomere of exopodite bearing 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. 9D View FIGURE 9 , D’). Exopodite a thin branchial plate, with 16 long plumose setae and 1 hirsute reflexed setulous seta. Basal podomere consisting of endopodite and 3 endites. Endopodite consisting 2 podomeres, carrying 4 hirsute setae on first podomere, 3 hook-shaped hirsute setae on distal end (1 of them very stout), and 1 simple seta on ventro-distal end of second podomere. Three endites bearing 5, 4 and 4 hirsute setae on distal end, respectively. Third endite also consisting of long hirsute seta on ventro-proximal margin, stout proximally.

Fifth limb ( Fig. 9E View FIGURE 9 ): Four articulated podomeres with terminal claw-like seta, length ratios from proximal to distal 11:6:3:4. First podomere with 1 short and 1 long hirsute setae in the middle of the anterior margin, 1 long hirsute seta at one-third of the 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. 9F View FIGURE 9 ). With four articulated podomeres, terminating with claw-like seta, length ratios from proximal to distal 18:14:5:8. First podomere bearing1 short hirsute seta in the middle of the anterior margin and 1 longer hirsute seta at two-third of the anterior proximal end, 1 very long hirsute seta at one-fifth of the 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 without seta.

Seventh limb ( Fig. 9G View FIGURE 9 ). Bearing four articulated podomeres, terminating with claw-like seta, length ratios from proximal to distal 36:30:11:16. First podomere with 1 very short and 1 longer hirsute setae at two fifth and at threefifth from proximal end on anterior margin, respectively, 1 hirsute seta at one-seventh from posterior proximal end on posterior margin, and 1 hirsute seta at anterior apical corner. Second podomere with setulae along margin and 1 hirsute seta at anterior apical corner. Third and fourth podomeres with setulae along anterior distal margin and carrying no seta.

Male copulatory organ ( Fig. 9H View FIGURE 9 ): Basal capsule subquadrate. Distal lobes large and thin, distally asymmetrical; left lobe terminating with large spine, right lobe with tiny spine and with rounded tip. Ejaculatory duct not conspicuous and terminating on distal lobe.

Furca ( Fig. 9I View FIGURE 9 ): Consisting of 1 long simple seta, 1 long hirsute and 1 short hirsute seta, on posterior distal end of male copulatory organ.

Brush-shaped organ ( Fig. 9J View FIGURE 9 ): Y- shaped in general; consisting of pair of branches with approximately 25–26 fine setae on each distal margin.

Dimensions. See Table 1.

Remarks. The carapace of Xestoleberis munensis sp. nov. is distinguishable from other previously described Xestoleberis species. In external lateral view, the carapace of this species is similar to that of X. hanaii , X. sesokoensis and X. ryukyuensis . However, the posterior part of the carapace of this species is angular ( Fig. 8A,B View FIGURE 8 ), whereas those of X. hanaii , X. sesokoensis and X. ryukyuensis are round. The copulatory organ of this species is similar to that of X. vietnamensis sp. nov., but there are clear differences between them: the right lobe of the distal lobes of this species has a tiny spine ( Fig. 9H View FIGURE 9 ), lacking in X. vietnamensis sp. nov. ( Fig. 7H View FIGURE 7 ). The copulatory duct of this species is not conspicuous, whereas that of X. vietnamensis sp. nov. is thick and question-mark shaped.