Fabaeformiscandona koreana, 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 : 23-27

Fabaeformiscandona koreana sp. nov.

( Figures 9–11 )

Etymology. The species is named after Korea. The name is in genitive singular.

Material examined. Holotype female (soft parts dissected on one slide, shell kept in ethyl alcohol NIBRIV0000245054a), paratypes (juvenile female in ethyl alcohol NIBRIV0000245054b), from (type locality) South Korea, Jilmoeneup, freshwater swamp, 37 0 47’49” N 128 0 40 ’41”E, 20/05/2006, collector Dongju Lee.

Description. Female: Carapace subrectangular in lateral view ( Figures 9 A, B; 10A, B) with the greatest H lying around middle L, equaling 47% of total L. Size: L= 1 mm. Dorsal margin very gently curved medially, rounded toward anterior end and sinusoid on postero-dorsal part. Anterior and posterior margins both broadly rounded and almost equally wide, posterior being slightly narrower than anterior one. Ventral margin concave around mouth region. Calcified inner lamella narrower posteriorly than anteriorly. Anteriorly equaling 10%, posteriorly less than 1% of total L. Lamella sinusoid in postero-ventral region, otherwise following contour of shell. 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, with one keel-like flange postero-dorsally.

A1 ( Figure 11 E). Appendage 7-segmented. First segment with two setae anteriorly and two posteriorly. One anterior seta situated more proximally, other distally on segment. Posterior setae originate from same (or very close) spot. All setae pappose. Second segment with one anterior pappose seta, not reaching distal end of fourth segment. Third segment with one anterior seta reaching distal margin of sixth segment. Fourth segment with one short posterior seta (reaching middle L of following segment), and two anterior, longer setae (exceeding distal end of terminal segment). Fifth segment with same chaetotaxy as fourth one, except that most posterior seta is much stiffer. Penultimate segment with total of four setae; posteriormost seta “d” absent (see arrow on figure 11E). Alpha seta exceeding distal end of terminal segment. Seventh segment ( Figure 11 F) with posterior, claw-like seta which is 2.4 times as long as terminal segment, one aesthetasc (ya), 1.6 times longer than terminal segment, and two longer setae. L ratio of five distal segments equaling: 1: 1.5: 1.2: 1.5: 1.7. Rome and Wouters organs not present.

A2 ( Figure 11 G). Basal segment (not illustrated) with total of three setae: one short, well-sclerotizedand pappose, other two smooth and longer. One of the long setae situated dorsally and one ventrally on segment. Distal segment of protopod with one, distal pappose seta exceeding distal margin of first endopodal segment. Exopod consisting of plate carrying one long (exceeding distal end of first endopodal segment) and two short, pappose setae. Endopod 3-segmented. First endopodal segment with aesthetasc “Y” and antero-ventrally with two long setae (one half as long as the other). Second segment with one medio-dorsal seta and four “t” setae ventrally. Same segment medio-ventrally with short aesthetasc y1. Claws G1, G2 and G3 all well developed, G2 reaching 2/3 of G1 and G3. Long claws as long as first endopodal segment. Only two “z” setae observed. Terminal segment with one long claw, GM (slightly shorter than first endopodal segment) and one short claw, Gm (2.3 times longer than terminal segment). Terminal segment also armed with aesthetasc y3 (longer than terminal segment) and one thin seta accompanying y3. Claws very gently serrated.

Md ( Figure 10 D). First segment of palp with one plumose seta (S1), one pappose, short seta (S2), alpha seta (short and smooth) and one additional pappose seta. Second segment dorsally with two setae, exceeding distal end of following segment, ventrally with beta seta, three plumose setae originating from a small plate, and one pappose seta. Penultimate segment dorsally with three almost equally long setae, gamma seta faintly pappose, and three additional setae of which one originating medially and two ventrally. Terminal segment with two strong, wellsclerotized claws and three setae more ventrally.

Mxl ( Figure 10 C). Palp 2-segmentd, 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.

L5 ( Figure 10 E). Exopod with two rays. One “a”, one “b” and one “d” seta present. Endopod distally with three short, subequal setae.

L6 ( Figure 11 A, B). Basal segment with one seta (d1). Endopod 4-segmented. Setae “e”, “f”, and “g” all relatively short and pappose. Terminal segment with distal claw and two lateral, short setae (h1 and h3). Distal claw as long as combined L of three distal segments.

L7 ( Figure 11 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 short seta. L ratios between three “h” setae equaling: 1: 2.9: 3.5.

UR ( Figure 11 D). Symmetrical, with posterior claw 2/3 of anterior one. 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. Posterior claw with clear spine medially (SEE ARROW ON FIGURE 11 D), and both claws also serrated. L ratios between anterior margin, anterior claw, posterior claw and posterior seta equaling: 4.7: 2.6: 1.7: 1

Genital field ( Figure 11 D). Two processes present, one more anterior, cylindrical with rounded distal end (see arrow on figure 11D), the other more prominent and subtriangular.

Male. Unknown.

Remarks and affinities. The new species clearly belongs to the genus Fabaeformiscandona because of the carapace shape, the presence of three setae on the internal side of the second segment of the Md-palp, and because of the absence of the most posterior (“d”) seta on the penultimate segment of the A1. As discussed under Candona quasiakaina sp. nov., the genus Fabaeformiscandona currently comprises many species which do not conform with the narrow definition of the genus proposed by Karanovic (2006). The genus comprises four groups of species: fabaeformiscandona – acuminata – balatonica –, and breuli – group. Species belonging to the first group have three setae on the second segment of the Md-palp, in acuminata – and breuli – groups, this segment is armed with four setae, while in balatonica – group there are five setae ( Meisch 2000, Smith & Kamiya 2007, Smith & Janz 2008). The following species belong to the fabaeformis – group: F. aemonae ( Klie, 1935) ; F. alexandri (Sywula, 1981) ; F. angusta ( Ostermeyer, 1937) , F. b r i s i a c a ( Klie, 1938), F. condylea Smith & Janz, 2008 ; F. dolabella Smith & Janz, 2008 ; F. fabaeformis (Fischer, 1851) ; F. fragilis (Hartwig, 1898) ; F. holtzkampfi (Hartwig, 1900) ; F. japonica (Okubo, 1990) ; F. krstici (Petkovski, 1969) ; F. myllaina Smith & Kamiya, 2007 ; F. okuboi Smith & Janz, 2008 ; F. paterea Smith & Janz, 2008 ; F. pedana Smith & Janz, 2008 ; F. s v e t o z a r i ( Petkovski& Karanovic, 2004); F. t o r a Smith & Kamiya, 2007; F. velifera Smith & Janz, 2008 , and F. yajimae Smith & Janz, 2008 .

Fabaeformiscandona aemonae ( Klie, 1935) , described from a cave in Slovenia, has a completely atypical appearance of the hemipenis, closely resembling Schellencandona Meisch, 1998 and/or Typhlocypris Vejdovský, 1882 and should be transferred to one of these genera. It is a similar case with F. b r i s i a c a, another stygobiont species, described from wells in the Rhine valley ( Klie 1938). Fabaeformiscandona angusta is known only after females ( Ostermeyer 1937, Meisch 2000), but the carapace shape and the genital field do not conform to the other representatives of Fabaeformiscandona , and this species is more likely to belong to Candona Baird, 1845 or Schellencandona .

The following species, described from Lake Biwa ( Smith & Janz 2008), have an isolated position within the genus: F. okuboi , F. condylea , and F. dolabella . The first species has a peculiar appearance of the hemipenis with the piece “M” missing, the prehensile palps do not have a typical fabaeformis appearance, but are less asymmetrical and simpler, and the genital field in females does not have any projections. The shape of the carapace is also with a less (if at all) pronounced sexual dimorphism, typical for the genus Fabaeformiscandona , and without a steep postero-dorsal margin in females. Fabaeformiscandona condylea was found in the interstitial of Lake Biwa, and, like F. okuboi , does not have a strong sexual dimorphism in the carapace shape, has simple, not hook-like fingers on the prehensile palp, and lacks piece “M” on the hemipenis. Additionally, the seta “z2” on the male A2 is not claw-like but is a simple seta. In all other Fabaeformiscandona both “z1” and “z2” are transformed into claws. The last species, F. dolabella , has a distinct “M” piece on the hemipenis, but the genital field lacks any projections, prehensile palps are simple and, like in F. condylea , “z2” is seta like. This species is more closely related to the breuli – group of the genus, having a similar carapace shape, morphology of hemipenis and prehensile palps. The breuli – group, on the other hand, has four setae on the Md-palp second segment internally. Fabaeformiscandona dolabella is probably more closely related to a group of North American Candoninae , such as C. crogmaniana Turner, 1985 , C. inopinata Furtos, 1933 and C. intermedia Furtos, 1933 with which it shares almost the same morphology of the prehensile palps and a similar hemipenis. Nevertheless, all those North American species have four setae on the Md-palp, and both “z1” and “z2” setae on the male’s A2 transformed into claws. It is interesting to note here that a “true” Fabaeformiscandona species has never been recorded from North America.

All other species listed above are closely related to the type species of the genus, F. f a b a e f o r m i s, and without any doubt form a clear phylogenetic lineage. The new Korean species is, unfortunately, known only after females, but the peculiar morphology of the genital field (two projections) and a strong spine on the posterior claw of the UR, clearly separate it from other congeners.

Figures

FIGURE 9. Fabaeformiscandona koreana sp. nov., holotype (female): A, LV, inside view; B, RV, inside view. Scales = 0.1 mm.

FIGURE 10. Fabaeformiscandona koreana sp. nov., holotype (female): A, LV, outside view; B, RV, outside view; C, Mxl palp; D, Md-palp; E, L 5. Scales = 0.1 mm.

FIGURE 11. Fabaeformiscandona koreana sp. nov., holotype (female): A, proximal part of L 6; B, distal part of L 6; C, L 7; D, UR with genital field, arrows shoring second projection on the genital field and the prominent spines on the claws; E, A 1, arrows pointing the absence of “ d ” seta; F, terminal segment of A 1; G, A 2. Scales = 0.1 mm.