Semicytherura kiosti Joest & Karanovic, 2022
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publication ID |
https://dx.doi.org/10.3897/fr.25.83276 |
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publication LSID |
lsid:zoobank.org:pub:BF8C7768-181B-4A75-9CF4-9C6F3DC6D559 |
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persistent identifier |
https://treatment.plazi.org/id/DAA1DAD2-32A5-4F02-8143-D0D158F8568B |
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taxon LSID |
lsid:zoobank.org:act:DAA1DAD2-32A5-4F02-8143-D0D158F8568B |
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treatment provided by |
by Pensoft |
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scientific name |
Semicytherura kiosti Joest & Karanovic |
| status |
sp. nov. |
Semicytherura kiosti Joest & Karanovic sp. nov.
Figs 8 View Figure 8 , 9 View Figure 9 , 10 View Figure 10 , 11 View Figure 11 , 12 View Figure 12
Note.
NIBR deposition number: DSEVIV0000003716.
Synonymy.
Hemicytherura sp. 3 sensu Ikeya and Itoh 1991: pg. 138, fig. 17A.
Etymology.
After the collaborating institution, Korea Institute of Ocean Science and Technology (KIOST), who provided the samples and funding for the MarineGEO project in Korea.
Diagnosis.
Sub-rectangular lateral outline (especially LV), as typical for species of the S. henryhowei group. Anteroventral margin with three crenulations (denticles). Carapace surface roughly pitted with finer, smaller pits at marginal areas. Dorsal margin straight, horizontal. Broadly acute caudal process above mid-height. Ventral margin straight, horizontal, but posterior half obscured by ventral ridge. Thick, prominent ridges on carapace, as typical for the Semicytherura henryhowei group. Prominent posterior subvertical ridge forming large, subtriangular fossa in posterior half of valve. Prominent, horizontal, straight anterior longitudinal ridge forming large, subtrapezoid fossa with dorsal half of anterior subvertical ridge.
Holotypes.
Two valves: adult male left valve, # 109_1 (lost, only SEM) and right valve, # 109_2 from ARMS sediment (i.e., surface and sedimentation-derived sediments).
Paratypes.
Five valves: # 68 (female ARV) and # 108 (male ARV) from ARMS sediment (i.e., surface and sedimentation-derived sediments), and # 177 (female A-1RV), # 239 (female A-2RV), # 240 (female ARV) from scoop sediment (i.e., surface sediment).
Type deposition.
Specimens are deposited at the National Institute of Biological Studies (NIBR, Incheon, South Korea) under the deposition number DSEVIV0000003716.
Type locality and age.
Seongsan (성산), Jeju Island, ROK (33°27'13"N, 126°56'45"E) (Fig. 2 View Figure 2 ), 19 m water depth. Extant (collection date 2019; surface and sedimentation-derived sediments; valves only, no soft bodies).
Description.
Heavily calcified, thick valve, sub-rectangular (LV) to ovoid (RV) in lateral view. Right valve larger than left valve (see Fig. 8 View Figure 8 , length/height plot, # 109_1 and # 109_2). Maximum height at anterodorsal corner. Dorsal margin is horizontal, straight, parallel to ventral margin. Ventral margin is obscured by overhanging ventral ridge at posterior half. Anterodorsal margin is smooth, obliquely rounded; antero-ventral margin with three small, acute marginal denticles; posterior margin is ascending in a straight line above the caudal process. Broadly acute posterior caudal process above mid-carapace.
The carapace surface is covered in rough pits, and pores with sensory hairs. Finer, smaller pits at marginal areas. Valve with thick ridges; anterior sublongitudinal ridge short, horizontal, straight line, terminating at anterior third of valve length; prominent posterior subvertical ridge connecting posterodorsal corner with ventral ridge at mid-length of valve; posterior ridge branching off posterodorsal corner and running in a straight, vertical manner to posterior corner; posterior subvertical ridge, posterior ridge and posterior half of ventral ridge form large, subtriangular fossa; anterior longitudinal ridge, dorsal half of anterior subvertical ridge, and anterodorsal margin form large, subtrapezoid fossa. Right valves slightly higher and longer than left valves. Females longer and slightly higher than males (see length/height plot, Fig. 8 View Figure 8 ).
Reticulation. Surface covered in large pits with prominent, species-specific ridge system.
Pores. Some simple pores with sensory hairs.
Hingement. Merodont hinge with a socket at each end of a ridge structure in the right valve (Figs 9A, C View Figure 9 , 10B, F, I View Figure 10 ). Complementary negative structures in the left valve (tooth at each end of a groove) (no SEM). Typical for genus. Hingeline arched.
Adductor muscle scars. Vertical row of 4 adductor scars in ventro-median area (Fig. 9 View Figure 9 ). Uppermost and lowermost scar less elongate in comparison with the middle two scars. At least 8 dorsal scars in upper half of valve (Fig. 11B View Figure 11 ). 2 mandibular scars slightly below, in front of adductor scars (Fig. 11F View Figure 11 , blue arrows). 2 frontal scars in front of two uppermost adductor scars (Fig. 11F View Figure 11 , white arrows).
Recurved inner. Strongly recurved in male adult (#109_2); absent in female adult (#240); not developed at juvenile stages (# 239) yet (Fig. 12 View Figure 12 ).
Dimensions.
Carapace dimensions of holotype: female ARV (# 240): length: 0.330 mm, height: 0.197 mm. Carapace dimensions of paratypes: female ARV: (# 68): length: 0.329 mm, height: posterior margin obscured by glue, ~ 0.196? mm; male ALV (# 109_1): length: 0.306 mm, height: 0.162 mm; male ARV (# 109_2): length: 0.308, height: 0.182 mm; male ARV (# 108): length: 0.310 mm, height: 0.185 mm; female A-2RV (# 239): length: 0.262 mm, height: 0.153 mm; female A-1RV (#177): length: 0.291 mm, height: 0.175 mm (Fig. 8 View Figure 8 ).
Occurrence.
Extant sediments, Korea (Jeju Island; surface and sedimentation-derived sediments collected 2019) and Japan (Sendai Bay, Matsushima Bay, Pacific Ocean; surface sediments collected 1985, 1986, 1988).
Remarks.
The present species is characterized by a short, straight, horizontal anterior longitudinal ridge (Fig. 4B View Figure 4 , AA). Of all known members of the Semicytherura henryhowei group, Semicytherura kiosti shares this trait only with S. leptosubundata (Fig. 4G View Figure 4 ) and S. neosubundata (Fig. 4Y View Figure 4 ). Morphological distinction between the three species based on prominent ridge patterns is straightforward. Semicytherura kiosti has an obvious anterior subvertical ridge, which is lacking in the other two species. Hemicytherura sp. 3 sensu Ikeya and Itoh 1991 is identical to our specimens of S. kiosti (fig. 17A in Ikeya and Itoh 1991). Hemicytherura Elofson, 1941 can easily be differentiated from the other members of the Semicytherura henryhowei group by the carapace surface features. Species of Hemicytherura , do exhibit something like ridges, but these do not resemble the characteristic ridge system of thick carinae of the S. henryhowei group. Rather, Hemicytherura is categorized by the characteristic fossa reticulation units that form around pores ( Tanaka et al. 2011). Species of the S. henryhowei complex also show a less coarsely pitted surface ornamentation when compared to the Hemicytherura species.
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