Itostenhelia polyhymnia, Karanovic & Kim, 2014

Karanovic, Tomislav & Kim, Kichoon, 2014, New insights into polyphyly of the harpacticoid genus Delavalia (Crustacea, Copepoda) through morphological and molecular study of an unprecedented diversity of sympatric species in a small South Korean bay, Zootaxa 3783 (1), pp. 1-96 : 54-65

publication ID	https://doi.org/ 10.11646/zootaxa.3783.1.1
publication LSID	lsid:zoobank.org:pub:E6155BDC-AEAE-475D-BC83-61B3B863344C
DOI	https://doi.org/10.5281/zenodo.5062495
persistent identifier	https://treatment.plazi.org/id/6878D460-FF9B-FF93-64D0-FAE102A7FCE1
treatment provided by	Felipe
scientific name	Itostenhelia polyhymnia
status	sp. nov.

Treatment

Itostenhelia polyhymnia sp. nov.

( Figs. 34–42 View FIGURE 34 View FIGURE 35 View FIGURE 36 View FIGURE 37 View FIGURE 38 View FIGURE 39 View FIGURE 40 View FIGURE 41 View FIGURE 42 )

Type locality. South Korea, South Sea , Gwangyang Bay, sampling station 10, muddy sediments, 34.897056°N 127.757722°E ( Fig. 1 View FIGURE 1 ) GoogleMaps .

Specimens examined. Female holotype dissected on one slide (collection number NIBRIV0000232691), male allotype dissected on one slide (collection number NIBRIV0000232692), female paratype dissected on one slide (collection number NIBRIV0000232693), one male paratype and three female paratypes together on one SEM stub (collection number NIBRIV0000232694), four male paratypes and seven female paratypes together in ethanol (collection number NIBRIV0000232695), type locality, 18 February 2012, leg. K. Kim.

One male paratype and 15 female paratypes together in ethanol (collection number NIBRIV0000232696), one female destroyed for DNA sequence (amplification unsuccessful), type locality, 18 November 2013, leg. K. Kim.

Three female paratypes (one ovigerous) together in ethanol (collection number NIBRIV0000232697), five females destroyed for DNA sequence (two successful, Codes 0176 & 0273), type locality, 30 July 2012, leg. K. Kim.

Three females (two ovigerous) destroyed for DNA sequence (amplification unsuccessful), South Korea, South Sea, Gwangyang Bay, sampling station 9, muddy sediments, 34.951389°N 127.734361°E ( Fig. 1 View FIGURE 1 ), 18 November 2012, leg. K. Kim. GoogleMaps

One female destroyed for DNA sequence (amplification unsuccessful), South Korea, South Sea, Gwangyang Bay, sampling station 16, muddy sediments, 34.768889°N 127.783806°E ( Fig. 1 View FIGURE 1 ), 18 November 2012, leg. K. Kim. GoogleMaps

Etymology. The species is named after Polyhymnia (Ancient Greek: Πολυύµνια), one of nine Muses from Greek mythology, who was a patron of sacred poetry and song. The species name is a noun in apposition (in the nominative case).

Description. Female (based on holotype and 12 paratypes). Body length from 405 to 428 µm (424 µm in holotype). Body segmentation, colour, nauplius eye, hyaline fringes, integument thickness as in Wellstenhelia calliope sp. nov. Surface appearance of prosomites extremely smooth and without minute pits even when examined on highest magnifications with scanning electron microscope; surface of urosomites mostly covered with numerous irregular rows of minute pits dorsally and laterally (see inset in Fig. 34A View FIGURE 34 ), except for hyaline fringes which generally smooth and slightly frilled. Most somite ornamentation similar to Wellstenhelia calliope , and presumed homologous pores and sensilla numbered with same Arabic numerals (see Figs. 34A, B, C View FIGURE 34 , 35A, B, C, D View FIGURE 35 , 37A View FIGURE 37 ) to allow easier comparison. Habitus ( Figs. 34A, B View FIGURE 34 , 39A View FIGURE 39 , 40A View FIGURE 40 , 16A View FIGURE 16 ) less robust than in Wellstenhelia calliope , prosome/urosome length ratio about one, body length/width ratio from 3.1 to 3.6, cephalothorax from 1.5 to 1.7 times as wide as genital double-somite.

Rostrum ( Figs. 34C View FIGURE 34 , 39B View FIGURE 39 ) general shape and position of anterior pair of sensilla no. 1 as in Wellstenhelia calliope but with additional bunch of ventral spinules just beyond tip (arrowed in Fig. 34C View FIGURE 34 ), with pronounced transverse dorsal suture (arrowed in Fig. 34C View FIGURE 34 ), and without dorsal pore no. 2.

Cephalothorax ( Figs. 34A, B View FIGURE 34 , 35A View FIGURE 35 , 39B View FIGURE 39 , 40B View FIGURE 40 ) about 1.1 times as long as wide; comprising 28% of total body length. Surface of cephalothoracic shield with 30 paired or unpaired sensilla and pores, most probably homologous to those in Wellstenhelia calliope (indicated with Arabic numerals in illustrations), 14 pores and sensilla missing (nos. 6, 10, 12, 16, 17, 18, 19, 21, 26, 29, 33, 34, 37, 40); absolute and relative positions of some pores and sensilla different; two lateral pairs of sensilla probably homologous to those in Wellstenhelia euterpe (indicated with geometric shapes in illustrations); one unique pair of dorsal pores (no. I) and one unique unpaired dorsal sensillum (no. II) located in central part of cephalothorax (also indicated with Roman numerals in illustrations).

Pleuron of second pedigerous somite ( Figs. 34A, B View FIGURE 34 , 39C View FIGURE 39 , 40C View FIGURE 40 ) ornamented as in Wellstenhelia calliope , except anterior lateral pair of sensilla no. 44 missing, unique pair of lateral pores (no. III), and unique pair of dorsal sensilla (no. IV).

Pleuron of third pedigerous somite ( Figs. 34A, B View FIGURE 34 , 35B View FIGURE 35 , 39C View FIGURE 39 , 40C View FIGURE 40 ) ornamented as in Wellstenhelia calliope , except anterior pair of dorsal pores no. 51 and anterior lateral pair of sensilla no. 52 missing (latter arrowed in Fig. 35B View FIGURE 35 ), and one unique dorsal pair of sensilla (no. V).

Pleuron of fourth pedigerous somite ( Figs. 34A, B View FIGURE 34 , 35B View FIGURE 35 , 39C View FIGURE 39 , 40C View FIGURE 40 ) as in Wellstenhelia calliope , except pair of anterior lateral pores no. 57 and pair of anterior lateral sensilla no. 62 missing (latter arrowed in Fig. 35B View FIGURE 35 ).

First urosomite ( Figs. 34A, B View FIGURE 34 , 39D View FIGURE 39 , 40D View FIGURE 40 ) as in Wellstenhelia calliope , except pair of anterior lateral pores no. 63 missing.

Genital double-somite ( Figs. 34A, B View FIGURE 34 , 35C, D View FIGURE 35 , 37A View FIGURE 37 , 39D View FIGURE 39 , 40D View FIGURE 40 ) as in Wellstenhelia calliope , except anterior part less inflated laterally, genital apertures situated more ventrally, all large spinules missing (arrowed in Figs. 35C View FIGURE 35 , 37A View FIGURE 37 ), anterior pair of pores no. 68 missing, and dorsal anterior pairs of sensilla nos. 69 & 70 more widely spaced; only more sclerotized part of genital apparatus visible inside and copulatory pores not visible on surface.

Third urosomite ( Figs. 34A, B View FIGURE 34 , 37A View FIGURE 37 , 40D View FIGURE 40 ) as in Wellstenhelia calliope , except all large spinules missing and one unique pair of ventral pores (no. VI) present (arrowed in Fig. 37A View FIGURE 37 ).

Preanal somite ( Figs. 34A, B View FIGURE 34 , 37A View FIGURE 37 ) without pores and sensilla, with numerous rows of minute spinules on dorsal and lateral sides, as in all urosomites.

Anal somite ( Figs. 34A, B View FIGURE 34 , 37A View FIGURE 37 , 39E View FIGURE 39 , 40E View FIGURE 40 ) general shape and ornamentation as in Wellstenhelia calliope , except ventral spinules along medial cleft (arrowed in Fig. 37A View FIGURE 37 ) and lateral pores nos. 79 & 80 missing, and anal operculum well developed, broad and smooth, reaching beyond distal margin of anal somite.

Caudal rami ( Figs. 34A, B View FIGURE 34 , 37A, B View FIGURE 37 , 39E View FIGURE 39 , 40E View FIGURE 40 ) shape and armature very similar to those in Wellstenhelia calliope , except dorsalmost lateral setae much stronger and conspicuously directed outwards (arrowed in Fig. 37A View FIGURE 37 ); rami cylindrical, about 1.7 times as long as anal somite, 3.5 times as long as wide (ventral view), slightly divergent or parallel, with space between them about one ramus width; ornamentation consisting of several large inner spinules in anterior part, single unique anterior pore in distal part (no. VII; arrowed in Fig. 37B View FIGURE 37 ), and several small spinules at base of dorsal and lateral setae and along dorsal and inner surface.

Antennula ( Figs. 34D View FIGURE 34 , 39F View FIGURE 39 ) similar to that in Wellstenhelia calliope but sixth and seventh segments almost completely fused, and eighth segment with only three lateral setae and without apical aesthetasc (all three features arrowed in Fig. 34D View FIGURE 34 ); only ornamentation single short row of small spinules in proximal half of first segment, distal row of spinules missing; aesthetasc on fourth segment reaching distal tip of appendage; setal formula 1.10.8.6+ae.3.(2.5).5.

Antenna ( Fig. 34E View FIGURE 34 ) as in Wellstenhelia calliope , except allobasis and first exopodal segment proportionately slightly shorter.

Labrum ( Fig. 41A View FIGURE 41 ) and paragnaths ( Fig. 41A View FIGURE 41 ) as in Wellstenhelia calliope , except labrum with additional spiniform process on anterior surface near distal margin.

Mandibula ( Figs. 35E, F, G View FIGURE 35 , 41A View FIGURE 41 ) similar to that in Wellstenhelia calliope but cutting edge without central seta (arrowed in Fig. 35E View FIGURE 35 ) and exopod with only one proximal seta (arrowed in Fig. 35G View FIGURE 35 ); both coxa and basis with more spinules than in Wellstenhelia calliope .

Maxillula ( Figs. 35H View FIGURE 35 , 41A View FIGURE 41 ) as in Wellstenhelia calliope , except exopod and endopod not fused (arrowed in Fig. 35H View FIGURE 35 ) and coxa without large anterior spinules.

Maxilla ( Figs. 35I View FIGURE 35 , 41A View FIGURE 41 ) as in Wellstenhelia calliope , except dorsal endite on syncoxa with only two setae (arrowed in Fig. 35I View FIGURE 35 ), syncoxa with only one arched row of outer spinules, and endopod with only four slender setae.

Maxilliped ( Figs. 35J View FIGURE 35 , 41A View FIGURE 41 ) segmentation, armature and most ornamentation as in Wellstenhelia calliope , but outer distal corner of coxa produced into pronounced and blunt process.

First swimming leg ( Figs. 36A View FIGURE 36 , 41B View FIGURE 41 ) as in Wellstenhelia calliope , except coxa and basis without inner spinules, first endopodal segment much shorter and its inner seta longer and stronger (both arrowed in Fig. 36A View FIGURE 36 ), and distal inner seta on second endopodal segment inserted further away from distal margin (arrowed in Fig. 36A View FIGURE 36 ).

Second swimming leg ( Figs. 36B, C, D View FIGURE 36 , 41B View FIGURE 41 ) as in Wellstenhelia calliope , except intercoxal sclerite with sharp distal projections (arrowed in Fig. 36B View FIGURE 36 ) and smooth, first endopodal segment with slender seta (arrowed in Fig. 36C View FIGURE 36 ), second endopodal segment with two inner setae (arrowed in Fig. 36C View FIGURE 36 ), and third exopodal segment with shorter distal inner seta (arrowed in Fig. 36D View FIGURE 36 ).

Third swimming leg ( Figs. 36E View FIGURE 36 , 41B View FIGURE 41 ) as in Wellstenhelia calliope , except intercoxal sclerite with sharp distal projections (arrowed in Fig. 36E View FIGURE 36 ), inner distal row of spinules on coxa missing (arrowed in Fig. 36E View FIGURE 36 ), third exopodal segment with only two outer spines and distal inner seta short and slender (both arrowed in Fig. 36E View FIGURE 36 ), first endopodal segment with slender inner seta (arrowed in Fig. 36E View FIGURE 36 ), and distal inner seta on third endopodal segment very short and slender (arrowed in Fig. 36E View FIGURE 36 ).

Fourth swimming leg ( Fig. 36F View FIGURE 36 ) as in Wellstenhelia calliope , except intercoxal sclerite with sharp distal projections (arrowed in Fig. 36F View FIGURE 36 ), third exopodal segment with only two outer spines and distal inner seta short and slender (both arrowed in Fig. 36F View FIGURE 36 ), and distal inner seta on third endopodal segment very short and slender (arrowed in Fig. 36F View FIGURE 36 ).

Fifth leg ( Figs. 34A, B View FIGURE 34 , 36G, H View FIGURE 36 , 37A View FIGURE 37 , 40D, F View FIGURE 40 ) segmentation, general shape, and number of armature elements on endopodal lobe as in Wellstenhelia calliope , except baseoendopod without spiniform process at base of exopod, with row of strong spinules instead (arrowed in Fig. 36H View FIGURE 36 ), additional anterior pore at base of basal seta. Exopod ovoid, about 2.1 times as long as greatest width, with long outer spinules (arrowed in Figs. 34A, B View FIGURE 34 , 36G View FIGURE 36 ), shorter inner spinules, and anterior pore, with five armature elements, second from inner side much longer than third (arrowed in Fig. 36G View FIGURE 36 ). Length ratio of endopodal setae, starting from inner side, 1: 1: 2.4: 1.5. Length ratio of exopodal setae, starting from inner side, 1: 0.5: 0.2: 0.7: 0.3.

Sixth legs ( Fig. 35C, D View FIGURE 35 ) simple cuticular plates covering paired genital apertures, inserted close to anterior margin of genital double-somite ventro-laterally, with single bipinnate seta, joined together into short but wide operculum.

Male (based on allotype and four paratypes). Body length from 357 to 412 µm (382 µm in allotype). Habitus ( Fig. 41C View FIGURE 41 ), colour, rostrum, shape and ornamentation of cephalothorax ( Figs. 38A View FIGURE 38 , 41D View FIGURE 41 ), second pedigerous somite ( Figs. 38A View FIGURE 38 , 41D View FIGURE 41 ), third pedigerous somite ( Fig. 38A View FIGURE 38 , 41D View FIGURE 41 ), fourth pedigerous somite ( Fig. 38A View FIGURE 38 ), ornamentation of first urosomite ( Fig. 37C View FIGURE 37 ), caudal rami ( Figs. 37C View FIGURE 37 , 38B View FIGURE 38 , 41F View FIGURE 41 ), antenna, labrum, paragnaths, mandibula, maxillula, maxilla, maxilliped, first swimming leg, third swimming leg, and fourth swimming leg as in female.

Genital somite ( Figs. 37C View FIGURE 37 , 38B View FIGURE 38 , 41E View FIGURE 41 ) somewhat wider than in Wellstenhelia calliope and without large spinules; lateral pore no. 68 missing; additionally ornamented with several rows of minute spinules dorso-laterally. Third urosomite ( Figs. 37C View FIGURE 37 , 38B View FIGURE 38 , 41E View FIGURE 41 ) as in Wellstenhelia calliope , except ventral row of spinules not interrupted between sensilla pair no. 73 (arrowed in Fig. 38B View FIGURE 38 ) and these sensilla also more widely spaced; additionally ornamented with several rows of minute spinules dorso-laterally.

Fourth urosomite ( Figs. 37C View FIGURE 37 , 38B View FIGURE 38 ) pore and sensilla pattern as in female (i.e. unique pore pair no. VI present), but additionally ornamented with ventral row of spinules of various sizes, some quite large.

Fifth urosomite ( Figs. 37C View FIGURE 37 , 38B View FIGURE 38 , 41F View FIGURE 41 ) without pores or sensilla as in female, but with posterior ventral row of spinules of various sizes, some quite large.

Anal somite ( Figs. 37C View FIGURE 37 , 38B View FIGURE 38 , 41F View FIGURE 41 ) as in female, except lateral pores nos. 79 & 80 present in allotype (missing in paratypes).

Caudal rami ( Figs. 37C View FIGURE 37 , 38B View FIGURE 38 , 41F View FIGURE 41 ) about four times as long as wide in ventral view, with two rows of relatively short inner spinules in anterior third.

Antennula ( Figs. 41C, D View FIGURE 41 ) as in Itostenhelia terpisichore , except completely clasped.

Second swimming leg ( Fig. 37D View FIGURE 37 ) with coxa, basis, and exopod as in female. Endopod significantly transformed, with second and third segment fused (arrowed in Fig. 37D View FIGURE 37 ), third segment smaller and without outer spinules (arrowed in Fig. 37D View FIGURE 37 ), outer apical spine enlarged, with small inner hump at proximal fifth of its length, mostly smooth, with only two anterior spinules at midlength and short row of slender inner spinules near distal tip; small notch on either side as remnant of ancestral segmentation; proximal seta on ancestral second segment short and slender, about as long as segment’s width; inner spiniform element on ancestral third segment also strong but bipinnate and not transformed, about 1.7 times as long as outer apical spine.

Fifth leg ( Figs. 37C View FIGURE 37 , 38B View FIGURE 38 , 41E View FIGURE 41 ) general shape and segmentation as in Wellstenhelia calliope but armature and ornamentation very different; fused endopodal lobes forming slightly convex plate, with four spines (two belonging to each leg; arrowed in Fig. 38B View FIGURE 38 ) and long posterior row of spinules between endopodal armature and exopod (arrowed in Fig. 38B View FIGURE 38 ); inner endopodal spine almost six times as long as outer one; exopod ovoid, with several outer spinules, with three inner setae (all short, slender, and smooth) and two apical spines, inner one fused basally to segment; outer apical exopodal spine only slightly shorter than inner endopodal spine and length ratio of exopodal armature, starting from inner side, 1: 0.45: 0.6: 0.3: 0.3.

Sixth legs ( Fig. 37C View FIGURE 37 , 38B View FIGURE 38 , 41E View FIGURE 41 ) as in Wellstenhelia calliope , except right leg distinct at base and more movable.

Variability. Most morphological features are extremely conservative, including the sensilla and pores pattern of somites, and length ratio of different armature on appendages. Except for body length, the only other variable feature was the presence/absence of lateral pores on the male anal somite ( Figs. 37C View FIGURE 37 , 38B View FIGURE 38 , 41F View FIGURE 41 ).

Morphological affinities. The Korean Itostenhelia polyhymnia sp. nov. is morphologically very similar to its only congener, the Russian Itostenhelia golikovi ( Chislenko, 1978) comb. nov. They show no differences in the antennula, antenna, mouth appendages or swimming legs, and even their sensilla and pores pattern on somites is exactly the same. That, and the fact that the original description of the Russian species by Chislenko (1978) was lacking in detail and contained several inaccuracies, was the reason we redescribe Itostenhelia golikovi below, also providing the first description of the male. Most major differences between these two species are all male characters, and they include proportions of the caudal rami (slightly longer in Itostenhelia polyhymnia ), size of the patch of spinules on the inner margin of the caudal rami (smaller in Itostenhelia polyhymnia ), relative size of the proximal inner seta on the ancestral second endopodal segment of the second leg (smaller in Itostenhelia polyhymnia ), relative length of the inner spiniform seta on the ancestral third endopodal segment of the second leg (shorter in Itostenhelia polyhymnia ), shape of the inner margin of the fused ancestral second and third endopodal segments of the second leg (with a noch in Itostenhelia polyhymnia ), and length of the outer endopodal seta of the fifth leg (shorter in Itostenhelia polyhymnia ). The females are extremely similar and can be distinguished mostly by the habitus size (smaller in Itostenhelia polyhymnia ) and shape (more slender in Itostenhelia polyhymnia ), in addition to the shape of the sclerotized parts of the genital receptacles (wider posterior parts in Itostenhelia polyhymnia ). All these differences are arrowed in the drawings of Itostenhelia golikovi (see Figs. 43A View FIGURE 43 , 44A View FIGURE 44 , 45A, B, D View FIGURE 45 ).