Candona sillae, Karanovic, Ivana & Lee, Wonchoel, 2012

Karanovic, Ivana & Lee, Wonchoel, 2012, A review of candonid ostracods (Crustacea: Ostracoda: Podocopida) from East Asia, with descriptions of five new species from South Korea *, Zootaxa 3368, pp. 7-49 : 15-20

publication ID	https://doi.org/ 10.5281/zenodo.281682
DOI	https://doi.org/10.5281/zenodo.6166596
persistent identifier	https://treatment.plazi.org/id/03D23B75-FF8C-FF86-FF5D-FAC6FF5F4C24
treatment provided by	Plazi
scientific name	Candona sillae
status	sp. nov.

Treatment

Candona sillae sp. nov.

( Figures 5–7 View FIGURE 5 View FIGURE 6 View FIGURE 7 )

Etymology. The species is named after Silla, one of the three ancient kingdoms of Korea (57 BC—935 AD).

Material examined. Holotype male (soft parts dissected on one slide, shell kept on the same slide in a drop of Faure’s medium NIBRIV0000245052), allotype female (soft parts dissected on one slide, shell kept on the same slide in a drop of Faure’s medium NIBRIV0000245053); 2 paratypes (1 female and 1 male in alcohol kept for future DNA studies), from (type locality) South Korea, Choenggye Mountain, freshwater stream, 37 0 25’25” N 127 0 03 ’55.2”E; 15/05/2011, collectors Hyunsu Yoo & Ivana Karanovic.

Description. Male. Carapace subtriangular in shape ( Figure 5 View FIGURE 5 C, D) with the greatest H lying well behind middle L, equaling 52% of total L. Size: L= 1.08 mm. Dorsal margin highly arched and with blunt angle at point of greatest H, then inclined towards posterior end and gently sloping towards anterior end. Anterior margin broadly rounded, while posterior one almost straight. Ventral margin concave around mouth region. Calcified inner lamella narrow on both ends, equaling less than 1% of total L. Fused zone also very narrow and marginal pore canals short, straight and denser anteriorly than posteriorly. Surface of shell covered with fine setulae, originating from small, but clear wart-like structures. No other surface ornamentation present. LV overlapping RV on all free margins.

A1 ( Figure 6 View FIGURE 6 A, B). Appendage 7-segmented. First segment with two setae anteriorly and two posteriorly. One anterior seta situated more proximally, the other distally on segment. Posterior setae originate from same (or very close) spot. All setae pappose. Second segment with one anterior pappose seta, not exceeding distal end of same segment. Third segment with one anterior, long and pappose seta slightly exceeding distal margin of fifth segment. Fourth segment with one short posterior seta (exceeding distal end of the same segment), and two anterior, longer setae (exceeding distal end of terminal segment). Fifth segment with same chaetotaxy as fourth one, except that posterior seta 1.5 times longer than on previous segment. Penultimate segment with total of five setae; posteriormost seta “d” present. Alpha seta slightly exceeding distal end of terminal segment. Seventh segment ( Figure 6 View FIGURE 6 B) with posterior, claw-like seta twice as long as terminal segment, one aesthetasc (ya) as long as terminal segment, and two other setae, one being slightly longer than claw-like seta, other being much longer. L ratio of five distal segments equaling: 1: 1.4: 1.6: 2: 1.8. Rome and Wouters organs not present.

A2 ( Figure 6 View FIGURE 6 G). Basal segment with total of three setae: one short, other two longer. One of the long setae situated dorsally and one ventrally on segment. Distal segment of protopod with one, distally pappose seta exceeding distal margin of fourth endopodal segment. Exopod consisting of plate carrying one long (almost reaching distal end of first endopodal segment) and two short, pappose setae. Endopod 4-segmented, penultimate segment being divided, carrying two male sexual bristles. First endopodal segment with aesthetasc “Y” and anteroventrally with two long setae (almost equally long). Second segment with one medio-dorsal (t4) seta, setae t3 and t2 transformed into sexual bristles (exceeding distal end of terminal segment) and one antero-ventral seta (t1). Same segment medio-ventrally with short aesthetasc y1. Third endopodal segment with claws G1, G2, G3, z1 and z2, and seta z3. Claws G1 and G3 short (60% of first endopodal segment): G2 long (1.1 times longer than first endopodal segment); z1 equaling 2/3 of z2 and latter approximately as long as first endopodal segment; z3 thin seta and half as long as z2 claw. Terminal segment with one long claw, Gm (approximately as long as first endopodal segment) and one short claw, GM (1.5 times longer than terminal segment). Terminal segment also armed with aesthetasc, y3 (as long as terminal segment) and one thin seta accompanying y3. Claws very gently serrated.

Md ( Figure 7 View FIGURE 7 A). First segment of palp with one plumose seta (S1), one pappose seta, and short alpha seta. Second segment dorsally with two setae, exceeding distal end of following segment, ventrally with pappose beta seta, five setae originating from a small plate and one plumose seta. Penultimate segment dorsally with three setae of which two are subequally long, and one almost half as long; gamma seta plumose, and three additional setae of which one originating medially and two ventrally. Terminal segment with two strong, well-sclerotized claws and two setae more ventrally.

Mxl ( Figure 7 View FIGURE 7 E). Palp 2-segmented, first segment with four setae: three originating antero-distally, and one medio-distally. All these setae pappose. Terminal segment with two claw-like setae and four setae, one situated between claws, and three situated more posteriorly.

Prehensile palps ( Figure 5 View FIGURE 5 G, H). Palps asymmetrical, right one with more curved dorsal margin and more curved finger. Finger on left palp much longer than body and almost straight. Both palps with well-developed subterminal structures.

L6 ( Figure 7 View FIGURE 7 C). Basal segment with one seta (d1). Endopod 4-segmented. Seta “e” and “f” reaching distal margins of their corresponding segments, seta “g” exceeding distal end of terminal segment. Terminal segment with distal claw and two lateral, short setae (h1 and h3). Distal claw approximately as long as combined L of three distal segments.

L7 ( Figure 6 View FIGURE 6 C). Basal segment with “d1” and “dp” setae. Seta “d2” missing. Endopod 4-segmented, and only “g” seta present distally. Terminal segment armed with two long and one very short seta (h1). L ratios between three “h” setae equaling: 1: 7.5: 7.5. Seta h1 as long as terminal segment.

UR ( Figure 6 View FIGURE 6 E, F). Symmetrical; posterior seta not very long and only reaching postero-distal margin of the ramus. Anterior seta much shorter and only ¼ L of anterior claw. Both claws faintly serrated. L ratio between anterior margin, anterior caw, posterior claw and posterior seta equaling: 2.7: 1.7: 1.4: 1. Attachment ( Figure 6 View FIGURE 6 D) with one dorsal and one ventral branch. Caudal seta present ( Figure 6 View FIGURE 6 D).

Hemipenis ( Figure 5 View FIGURE 5 E). Medial lobe ( Figure 5 View FIGURE 5 F) well-sclerotized with boxer glove-like distal end. Lobe “h” slightly pointed on its distal end. Lobe “a” subdivided into three sub-lobes, more dorsal and medial tongue-like, lower square-shaped. Inner duct not coiled.

Zenker organ with seven rows of spines.

Female. Slightly smaller than males ( Figure 5 View FIGURE 5 A, B), L= 1 mm. Sexual dimorphism clearly pronounced in shape of posterior margin, which is straighter in females than in males. Also, ventral margin not as concave around mouth region as in males.

A2 ( Figure 7 View FIGURE 7 B). Endopod 3-segmented. All “t” setae on penultimate segment present, subequally long and pappose; three of those exceeding distal end of terminal segment. None of “z” setae transformed into claws exceeding distal end of terminal segment. Claw G2 equaling 2/3 of claw G1 which is slightly longer than first endopodal segment. Claw G3 same as claw G1. Terminal segment with long claw Gm and short Gm. All claws gently serrated.

L5 ( Figure 7 View FIGURE 7 F). One “a”, “b” and “d” setae present. Terminal setae on endopod short, two subequally long and one slightly longer.

L7 ( Figure 7 View FIGURE 7 G) with slightly longer h1 seta than in males.

UR ( Figure 7 View FIGURE 7 D) Similar to male, two rami. Ramus also much wider proximally than in males. L ratios between anterior margin, anterior, posterior claw and posterior seta equaling: 2.5: 1.3: 1: 1.

Genital field ( Figure 7 View FIGURE 7 D). Projection globular, slightly pointed distally.

All other appendages same as in male.

Remarks and affinities. The new species is very closely related to Candona improvisa Ostermeyer, 1937 . They are the only two species of the genus Candona that have a very short, and even peculiarly curved seta “h1” on the L7. In all other Candona species this seta is much longer. A short “h1” seta is often encountered in the genus Typhlocypris , i.e. in eremita - and rostrata -groups. Candona improvisa was described from Saxony-Anhalt, Germany ( Ostermeyer 1937) and is known from Hungary, Poland and Slovakia ( Meisch 2000). In both species the outer lobe on the hemipenis is subdivided: in the Korean species it is subdivided in three, while in the European species it is divided in two lobes. The other difference between the two species is the shape of the medial part (piece “M”) on the hemipenis, which is distally more rounded in C. improvisa . Genital field is also more acutely pointed in this species than in C. sillae . Other minor differences are related to the length of setae on the L6, while the A1, A2, Md, Mxl, L5, L7, and UR are almost identical in both species. A similar appearance of the lobe “a” is present in the North American Candona inopinata Furtos, 1933 , described from Ohio ( Furtos 1933) and redescribed based on the type material by Karanovic (2006). The American species, however, has four setae on the inner side of the second segment of the Md-palp, a different carapace shape (much higher in the lateral view), a different shape of the right prehensile palp, a finger-like projection on the genital field, and a long “h1” seta on the L7.