Typhlocypris (Pseudocandona) pratensis (Hartwig, 1901)

Karanovic, Ivana, 2013, Earicandona, new genus and the first record of Typhlocypris pratensis (Crustacea, Ostracoda) from South Korea, Journal of Species Research 2 (2), pp. 145-158 : 153-156

Typhlocypris (Pseudocandona) pratensis

( Hartwig, 1901) ( Figs. 6 C-E, 7)

Synonymy. [non] Candona compressa n. sp. - Kaufmann, 1900: p. 371, Pl. 27, Figs. 4-6 , Pl. 28, Figs. 6 -11, Pl. 31, Fig. 18

Candona pubescens n. sp. - Müller, 1900: p. 26, Pl. 4: 3- 4, 6, 16, 18-19, 21-22.

Candona pratensis nom. nov. - Hartwig, 1901: p. 109

Pseudocandona pratensis ( Hartwig, 1901) comb. nov. - Danielopol, 1980: p. 747.

Typhlocypris (Pseudocandona) pratensis ( Hartwig, 1901) comb. nov. - Karanovic, 2005: p. 399.

Material examined. One female ( NIBRIV0000270972 ) dissected on one slide (shell not kept) from Gangwon-do , South Korea, 2011/04/23, collectors Choi & Kim.

One female ( NIBRIV0000270973 ) dissected on one slide, shell on SEM stub, one female ( NIBRIV0000270 974) in alcohol from Banbyeoncheon (River), Andong, Gyeongsangbuk-do, South Korea, 36̊32.386 ′N 128̊ 49.036′E, 2012/04/05, collector I. Karanovic.

Description. Female: Shell almost rectangular in shape ( Fig. 6C ), L= 0.8 mm. Greatest H situated behind middle, equaling 55% of L. Dorsal margin rounded toward posterior end, and sloping towards anterior end, with a slight sinusoid depression antero-dorsally. Both anterior and posterior margins rounded, posterior one wider. Ventral margin almost straight, except around middle where slightly concave. Anterior and posterior inner calcified lamella narrow ( Fig. 6E ). Surface of the shell covered with hair-like setae originating from well-defined ringed openings ( Fig. 6D ).

A1 ( Fig. 7A ) 7-segmented. First segment anteriorly with one proximal and one distal seta; posteriorly same segment with two long setae situated distally. Second and third segments with one antero-distal seta each (none of the two setae reaching distal margins of following segments). Fourth segment with one short postero-distal and two long antero-distal setae. Fifth segment with the same chaetotaxy as fourth one. Sixth segment with short α-seta, two long and one short seta. Terminal segment with aesthetasc (ya) which approximately 1.5 times longer than seventh segment, one short posterior seta, and two long setae. L ratio between last five segments equal: 1: 1.6: 1.8: 1.9: 1.7. Segments one and two, and two and three articulated.

A2 ( Fig. 7B ) with 3-segmented endopod. Basal segment with two setae. Protopod with one long seta. Exopod reduced to plate with one long and two short setae. First endopodal segment with two postero-distal setae (unequally) long, and aesthetasc Y which not reaching distal end of first endopodal segment. Aesthetasc y1 situated slightly above four t setae, one more short seta present posteriorly on same segment. Claw G2 reduced, but exceeding terminal segment, claws G1, G3, GM, long, Gm equaling 2/3 of GM. All z-setae normal and not transformed in claws. Aesthetasc y2 short, y3 as long as terminal segment. L ratio between endopodal segments: 4.3: 2.8: 1.

Md ( Fig. 7D ) with 4-segmented palp, stout coxa and exopod carrying vibratory setae. First segment internally with two long setae (pappose one being S1), seta S2 short and plumose, while α- seta smooth and tiny. Following segment with two long setae externally and a group of 5 +2 setae internally on segment. Third segment with three long outer extero-distal setae, two medio-distal setae (γ-seta smooth) and two intero-distal setae (one long, other short). Terminal segment with two strong claws and three setae situated more internally on segment.

Mxl ( Fig. 7C ). Palp 2-segmented. First segment with four setae distally, three plumose, one smooth. Terminal segment with two claws and four setae. Third endite with several claws and several setae.

L5 ( Fig. 7E ). Protopod of with one a, one b, and one d-seta. Endopod with three apical setae unequal in L.

L6 ( Fig. 7F ) 5-segmented. Penultimate segment with posterior margin sometimes undivided. Basal segment with d1 seta. All setae (e, f, and g) present on endopod. Terminal segment with one strong claw, only lightly serrated. Terminal claw 1.3 times as long as three terminal segments combined.

L7 ( Fig. 7G ) 5-segmented, penultimate segment subdivided. Basal segment with d1 and d2 setae shorter than dp, all three setae serrulate. Setae e and f missing, while seta g long and serrulate. Terminal segment with one short and two long setae. Length ration between h1, h2 and h3 setae: 1: 2.7: 2.7.

UR ( Fig. 7I ) with stout ramus and both claws and setae present. Posterior seta exceeding distal margin of ramus. Anterior claw slightly longer than posterior one. L ratio between anterior margin, anterior and posterior claws equaling: 1.4: 1.2: 1. Both claws serrated. Attachment of UR ( Fig. 7H ) with one dorsal and one ventral branch. Genital field rounded without any projections.

Remarks and affinities. Typhlocypris (Pseudocandona) pratensis ( Hartwig, 1901) is relatively common species in Europe ( Meisch, 2000), with a wide ecological tolerance and often unequal proportion of males and females in its populations. It belongs to the compressa -group of the genus, defined by the presence of 5+2 setae on the inner side of the second segment of the Md-palp, a 5-segmented L7, and the seta h1 on the terminal segment of the same appendage much longer than the segment itself.

Although we have not found males, we positively identify the species collected from Korea as P. pratensis because of the valve shape, morphology of the UR, and the length of G2, which is longer than the terminal segment. This last feature clearly distinguishes T. (P.) pratensis from, T. (P.) compressa (Koch, 1838) , T. (P.) insculpta ( Müller, 1900) , T. (P.) regisnikolai ( Karanovic & Petkovski, 1999) , and T. (P.) sucki ( Hartwig, 1901) where the G2 on the female A2 is considerably shorter. Only T. (P.) albicans (Brady, 1864) has the same length of the G2 claw as T. pratensis , but these two species can easily be distinguished by the carapace shape, because the posterior end is much higher in T. pratensis , and T. albicans is more elongated in lateral view.

Figures

Fig. 6. SEM. A, B. Earicandona mounchyon n. gen. n. sp., paratype female. C-E. Typhlocypris (Pseudocandona) pratensis (Hartwig, 1901). A. shell, lateral view from the left side. B. detail of the anterior margin. C. shell, lateral view from the right side. D. opening of the surface seta. E. RV, postero-ventral margin, inside view.

Fig. 4. Earicandona mounchyon n. gen. n. sp. Holotype, male. A. left palp. B. Right palp. C. L6. D. L7. E. hemipenis. F. UR. G. attachment of the UR. Scales=0.1 mm.

Fig. 5. Earicandona mounchyon n. gen. n. sp., Allotype, female. A. UR, with genital field. B. endopod of A2. C. protopod of L5. D. lateral view from the left side. Scales=0.1 mm.

Fig. 7. Typhlocypris (Pseudocandona) pratensis (Hartwig, 1901). A. A1. B. A2. C. Mxl. D. Md. E. L5. F. L6. G. L7. H. attachment of the UR. I. UR. Scales=0.1 mm.