Earicandona mounchyon, Karanovic, 2013

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 : 148-153

publication ID	https://doi.org/ 10.12651/JSR.2013.2.2.145
DOI	https://doi.org/10.5281/zenodo.8124997
persistent identifier	https://treatment.plazi.org/id/03818791-FFA9-FFFB-FCB1-B162FD5FF865
treatment provided by	Felipe
scientific name	Earicandona mounchyon
status	sp. nov.

Treatment

Earicandona mounchyon sp. nov.

( Figs. 2 View Fig , 3 View Fig , 4 View Fig , 5 View Fig , 6A, B View Fig )

Material examined. Holotype - male ( NIBRIV0000279 526), dissected on one slide, shell not kept (broken during dissection).

Allotype - female ( NIBRIV0000279527 ), dissected on one slide, shell not kept (broken during dissection).

Paratypes - two males and one female on the SEM slide ( NIBRIV0000279528 ) , 6 females, 3 males, and 1 juvenile kept in 99% ethyl-alcohol.

Type locality. Sample taken in the area around a dead fish ( Fig. 1B View Fig ), Yongjiho Lake, Gangwon-do, South Korea, 38̊13.697 ′N 128̊33.868 ′E, 2012/04/16, collector I. Karanovic.

Etymology. The species is named after the Greek noun Mounchyon , meaning April, referring to the month when the species was collected.

Description. Male: Carapace reniform ( Figs. 2A View Fig , 3A View Fig ). L= 0.75 mm. Greatest H situated behind middle, equaling 50% of L. Dorsal margin arched behind middle, than rounded towards posterior and gently sloping towards anterior end. Posterior and anterior margins rounded and equally wide. Ventral margin gently concave, and with prominent enlargement around mouth region ( Fig. 2C View Fig ). Postero dorsal margin of LV without prominent keel ( Fig. 2D View Fig ). Inner calcified lamella narrow anteriorly and posteriorly. Marginal pore canals short and relatively dense. Surface of shell smooth, antero-dorsally with two short ridges ( Fig. 2B View Fig ). Surface sparsely covered with hair-like setae (sensory setae) ( Fig. 2E View Fig ).

A1 ( Fig. 3B View Fig ) 7-segmented. First segment anteriorly with one proximal and one distal seta, both serrulate; posteriorly same segment with two long setae situated distally. Second and third segments with one serrulate antero-distal seta each. Fourth segment with one postero-distal and two antero-distal setae; postero-distal seta slightly exceeding distal margin of following segment, anterior setae much longer. 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: 1.1: 1.1: 1.4: 1.6. Segments one and two, and two and three articulated.

A2 ( Fig. 3C View Fig ) with 4-segmented endopod. Basal segment with two setae. Protopod with one long seta. Exopod reduced to plate with one long and two short setae ( Fig. 2F View Fig ). First endopodal segment with two postero-distal setae (unequally) long, and aesthetasc Y which barely reaching distal end of first endopodal segment. Following segment subdivided with two male sexual setae. Aesthetasc y1 situated slightly above these. Seta t4 as long as male sexual setae, while seta t1 much shorter; one more short seta present next to t1. Claws G1 and G2 reduced, G1 still claw-like but only two times longer than terminal segment, G3 as long as G1 but transformed into seta; claw G2 long and strong. Setae z1 and z2 transformed into strong claws, subequally long and as long as G2, z3 seta like ( Fig. 2G View Fig ). Terminal segment carrying two claws (GM and Gm), aesthetasc y3, and one additional seta. GM shorter than Gm. Aesthetasc y2 not observed. L ratio between endopodal segments: 4.2: 2.2: 1.7: 1.

Md ( Fig. 3E View Fig ) with 4-segmented palp, stout coxa and exopod carrying vibratory setae. First segment internally with two plumose setae, more distal one representing S1 seta, seta S2 short and plumose, while α- seta smooth and tiny. Following segment with two long setae externally and a group of 3+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 central claw distally pappose, one strong seta on its external side and two setae on its internal side (one short other as long as external seta).

Mxl ( Fig. 3D View Fig ). Palp 2-segmented, distally slightly dilated. First segment with four setae distally, two plumose, two smooth. Terminal segment with two claws and four setae. Third endite with five claws and several setae.

L5 ( Fig. 4A, B View Fig ). Palps asymmetrical: right one ( Fig. 4B View Fig ) stockier than left one ( Fig. 4A View Fig ). Right palp also with sinusoid dorsal margin. Both fingers very short, left one terminating with stronger tips. Protopod of L5 with one a, one b, and one d-seta. One seta present on exopod.

L6 ( Fig. 4C View Fig ) 5-segmented. Basal segment with d1 seta. All setae (e, f, and g) present on endopod, and all serrulate. Terminal segment with one strong claw, only lightly serrated. Terminal claw 0.8 times as long as three terminal segments combined.

L7 ( Fig. 4D View Fig ) 5-segmented, penultimate segment clearly subdivided. Basal segment with short d1 and longer dp seta; both 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: 1.4: 2.1.

UR ( Fig. 4F View Fig ) with long ramus and both claws and setae present. Posterior seta not reaching distal margin of ramus. Anterior claw slightly longer than posterior one. L ratio between anterior margin, anterior and posterior claws equaling: 2.6: 1.3: 1. Both claws lightly serrated. Attachment of UR ( Fig. 4G View Fig ) without any branching.

Hemipenis ( Fig. 4E View Fig ) with laterally projecting, triangular lobe a. This lobe with rounded tip, lightly striate and with one longitudinal sclerified patch. Both lobe b and h rounded, and hard to distinguish one from another. Lobe g not clear as well, only its basal part. Ejaculatory projection e with sclerified tip. Inside structures of hemipenis consist of several sclerified patches some probably belonging to lobe g. Inside canals not coiled.

Female: Carapace much lower from male ( Figs. 5D View Fig , 6A View Fig ), L= 0.8 mm. Dorsal margin not arched as in male, slightly sinusoid postero-dorsally. Greatest H 47% of L. Surface of shell as in male ( Fig. 6B View Fig ), but no anterior striae present.

A2 ( Fig. 5B View Fig ) with long G1 and G3 claws, while G2 slightly shorter. All z setae unchanged.

L5 ( Fig. 5C View Fig ) with three apical, subequally long setae on endopod.

UR ( Fig. 5A View Fig ) with posterior seta slightly longer than in males. Caudal seta longer than in males. Genital field with only small protruding projection. Attachment of UR with one lateral branch starching towards genital field.

Other soft parts same as in male.

Remarks and affinities. Beside the new species, the genus Earicandona gen. nov. contains only E. okuboi ( Smith & Janz, 2008) comb. nov., described from the Lake Biwa ( Smith & Janz, 2008). Two species share a very similar hemipenis and prehensile palp morphology. On the other hand they differ in the shell shape, especially considering the sexual dimorphism, which is more pronounced in E. mounchyon sp. nov. Males of the new species have more inflated posterior end of the shell, and have a prominent enlargement on the ventral margin of the shell in the mouth region. The following details in the soft part morphology clearly separate the two species:

1. Seta z 2 in E. okuboi male is thinner than in E. mounchyon .

2. Claw G 2 in E. okuboi female is shorter in comparison to the G1 and G3 claws than in E. mounchyon .

3. Posterior claw on the UR is shorter in comparison to the anterior claw in the new species.

4. Female genital field is evenly rounded in Japanese species, while there is a small but clear triangular projection in E. mounchyon .

Other species that can potentially belong to Earicandona is Fabaeformiscandona condylea Smith & Janz, 2008 , also know from Lake Biwa ( Smith & Janz, 2008). Similar to E. mounchyon sexual dimorphism in carapace is more pronounced. It also has a relatively small but prominent projection on the genital field, however larger than in the new species. Prehensile palps are also short and stocky, although the left one does not have arched dorsal margin. In addition to all this, F. condylea lacks lobe g on the hemipenis, a character which may indicate the close relationship. Two main reasons for yet not including F. condylea into the new genus are: a peculiar position of the lobe a on the hemipenis (not laterally projected), and the seta z2 on the male A2 not transformed into a claw. Fabaeformiscandona bilobata (Klie, 1938) and F. bilobatoides (Löffler, 1961) have a very similar hemipenis like F. condylea , what was also noticed by Smith & Janz (2008). These two species are only known from Germany and Austria, and according to Meisch (2000) they may even be synonyms. Nevertheless, the morphology of prehensile palps of F. bilobata and F. bilobatoides is similar to Earicandona , with longer fingers, especially on the left palp in F. bilobatoides . These two species belong to the breuili -group of the genus Fabaeformiscandona Krstic, 1972 , characterized by a small genital lobe, and a group of 4+2 setae on the inner side of the second segment of the Md-palp. So far the group contains four species, and beside F. bilobatoides and F. bilobata males are known only for F. latens (Klie, 1940) , while only females are known for F. breuili (Paris, 1920) , except for the rare males known only from the fossil record (Diebel & Pietrzeniuk, 1984). Fabaeformiscandona latens is the only species of the group with apparently prominent lobe g on the hemipenis, and a subdivided segment on the L7. In all other species the L7 is 4-segmented. So far, all species of the breuili -group live in subterranean waters ( Meisch, 2000) and reduction in the number of segments is not rare within Candoninane living in this environment (see Danielopol, 1978; Karanovic, 2007). When establishing this group, Meisch (2000) pointed out also the small size of animals and elongated claws on the A2, another two characters of the stygobiont ostracods. In my opinion, F. latens is not closely related to other members of the breuili -group, and the other three species will most likely proven to belong to a different genus, if not Earicandona , than certain to a very closely related one.