Pseudameira mago Karanovic & Cho, 2012, sp. nov.
Creators: name: Karanovic, Tomislav
name: Cho, Joo-Lae
Publisher: name: Zenodo
Year: 2012
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Maxillopoda
Harpacticoida
Ameiridae
Pseudameira
Pseudameira mago

description: Pseudameira mago sp. nov.
(Figs. 8 & 9)
Type locality. South Korea, South Sea, Memuld Island, littoral, depth 33 m, 34.654683°N 128.593633°E.
Specimens examined. Types only: holotype ovigerous female dissected on one slide (collection number NIBRIV0000232639), one paratype ovigerous female in toto on slide (collection number NIBRIV000023264040), and one paratype ovigerous female dissected on one slide (collection number NIBRIV0000232641); all collected from type locality, 18 December 2010, temperature 15.1 °C, salinity 33.84 psu, pH 7.54, leg. W. Lee.
Etymology. The species name is taken from the Korean totemic and shamanistic mythology, and reffers to a goddess named Mago, one of the first two deities that appeared at the beginning of the world. Although totemic and shamanistic legends play a minor part in the religious landscape in Korea today, their influence is evident in the love and respect most people here show for the nature in general, and Korean mountains especially. The name thus should be treated as a Latin noun (gender feminine) in apposition to the generic name.
Description. Female (based on holotype and two paratypes). Total body length, measured from tip of rostrum to posterior margin of caudal rami (excluding appendages and caudal setae), from 412 to 427 μm (412 μm in holotype). Preserved specimen yellowish. Nauplius eye not visible. Body segmentation as in previous two species. Most somite ornamentation also similar to previous species, and presumably homologous pore and sensilla also numbered with same Arabic and Roman numerals (see Fig. 8 A, B) to allow easier comparison. Habitus (Fig. 8 A, B) almost perfectly cylindrical in dorsal view, only gently tappering towards posterior end, slender; podoplean boundary between prosome and urosome almost inconspicuous in dorsal view, but more pronounced in lateral view; prosome/urosome ratio nearly 1.1 and greatest width in dorsal view at posterior end of cephalothorax. Body length/width ratio about 4.8; cephalothorax 1.1 times as wide as genital double-somite. Free pedigerous somites without lateral or dorsal expansions, pleural plates better developed than in previous two species, almost completely covering coxae of swimming legs in lateral view. Integument relatively strongly chitinized, without cuticular windows or pits. Surface ornamentation of somites consists of 62 pairs and five unpaired pores and sensilla (those homologous with previous two species indicated with Arabic and Roman numerals respectively in Fig. 8 A, B, C; those not present in previous species indicated with Greek letters in alphabetical oder from anterior to posterior end of body, and from dorsal to ventral side), and several rows of spinules on urosomites only. Lateral pair of sensilla no. 14 on cephalothorx probably homologous to cuticular pores no. 14 in previous two species. Rostrum small, membranous, linguiform, with relatively blunt tip, reaching 1/3 of first antennular segment, about twice as long as wide and not demarcated at base; ornamented with two dorsal sensilla (pair no. 1).
Cephalothorax (Fig. 8 A, B) gradually tapering towards anterior end in dorsal view, about 1.2 times as long as wide; represents 24% of total body length. Surface of cephalic shield without any pores, ornamented with one unpaired dorsal sensillum (no. V) and 23 pairs of long sensilla (nos. 2, 3, 5–8, 10, 12–16, 18–20, 24–26, III, VI, α, β, γ); sensilla 19–26 & VI belong to first pedigerous somite. Second pedigerous somite (first free) without pair of pores antero-laterally, ornamented with seven pairs of long sensilla (nos. 27, 29–31, 33–35); antero-dorsal pair of sensilla (no. 27) serially homologous to pair no. 19 on first pedigerous somite. Third pedigerous somite also without antero-lateral pair of pores, ornamented with six pairs of long sensilla (nos. 36, 38, 40, 41, 44, 45); anterodorsal pair of sensilla (no. 36) serially homologous to pairs nos. 19 and 27 on previous two pedigerous somites. Fourth pedigerous somite also missing antero-dorsal pair of pores, as in previous two somites, ornamented with six pairs of long posterior sensilla (nos. 47–50, 52, 53). Hyaline fringes of all prosomites braod and smooth, except on fourth pedigerous somite where fringe relatively narrow dorsally. Fifth pedigerous somite ornamented only with four pairs of posterior sensilla (nos. 54–57); hyaline fringe smooth and narrow.
Genital double-somite (Fig. 8 A, B, C) 1.2 times as long as wide (ventral view); internal suture (remnant of segmental fusion) strongly sclerotised, visible dorsolaterally at midlength of somite, furnished with two parallel short rows of strong spinules dorsolaterally, four pairs of sensilla (nos. 59–62), and lateral pair of cuticular pores (no. 63); posterior part of genital double-somite without lateral pores, ornamented with one unpaird ventral pore (no. 66), one dorsal unpaired pore (no. IX), posterior row of large spinules on eash side laterally, and four pairs of posterior sensilla (nos. 67–70); hyaline fringe finely serrated. Genital complex (Fig. 8 C) with single large copulatory pore, strongly sclerotized and wide copulatory duct and two small ovoid seminal receptacles. Single median genital aperture covered by fused reduced sixth legs, represents 55 % of somite’s width. Third urosomite ornamented with posterior row of spinules (interrupted dorsally), unpaired dorsal cuticular pore (no. 71), two pairs of cuticular pores (nos. 73, δ) ventrally and laterally respectively, unpaired dorsal posterior sensillum (no. 74), and three pairs of posterior sensilla (nos. 75–77); hyaline fringe finely serrated. Fourth urosomite ornamented with single pair of lateral cuticular pores (no. ε), and short posterior row of slender spinules ventrally; hyaline fringe finely serrated. Anal somite (Fig. 8 B, C, D) deeply clefted medially (only anterior third of somite not clefted), with transverse internal sclerotised ridge in anterior side which interrupted medially by cleft, ornamented with pair of large dorsal sensilla (no. 81), two pairs of cuticular pores (nos. 80, 85), two parallel ventral anterior rows of slender spinules, ventro-lateral posterior row of spinules at base of each caudal ramus; anal operculum slightly convex, narrow and relatively short, reaching 3/4 of anal somite and covering anterior half of medial cleft, represents 33% of somite's width, smooth; anal sinus ornamented with two parallel diagonal rows of hair-like spinules on each side of median cleft, widely open, with weakly sclerotised walls, and without any chitinous projections.
Caudal rami (Fig. 8 B, C, D) short but robust, about as long as anal somite in dorsal view, nearly 1.5 times as long as wide (ventral view), slightly divergent and cylindrical (posterior part slightly narrower), space between rami about 1.8 times one ramus width, without dorsal diagonal suture in anterior half; with seven elements (three lateral, one dorsal and three apical); ornamentation consists of two spinules at base of largest lateral setae, two ventral posterior spinules at base of inner apical seta (outer minute), and two pairs of pores (nos. 87, 88). Dorsal seta relatively short and slender, smooth, inserted on postero-median corner, about 0.8 times as long as caudal ramus, triarticulate at base. Lateral setae all smooth and slender; distalmost seta longest, inserted closer to ventral side and very close to posterior margin, 2.6 times as long as smaller proximal seta, 1.3 times as long as larger proximal seta, and also 1.3 times as long as caudal ramus; proximal lateral setae inserted very close to each other in cuticular depressions similar to those of typical sensilla, inserted very close to dorsal side and posterior margin. Inner apical seta smooth, about 1.2 times as long as ventralmost lateral seta. Middle apical seta strongest, with breaking plane, finely bipinnate at middle third of its length, 1.1 times as long as urosome and twice as long as outer apical seta. Outer apical seta also with breaking plane and strong, finely bipinnate distally.
Antennula (Fig. 9 A) six-segmented, joined to cephalotholax with small triangular pseudosegment laterally, approximately half as long as cephalothorax, ornamented with very long spinules along posterior margin of second segment and several small spinules on anterior margin of first segment. Long aesthetasc on fourth segment reaching beyond tip of appendage for length of last four segments combined, wider than in previous two species, fused basally with even longer adjacent seta; slender apical aesthetasc on eighth segment about as long as last three segments combined, fused basally with two apical setae, forming apical acrothek. Setal formula: 1.8.7.3.2.14. One seta on second segment, one on third, and three setae on sixth segment pinnate; all other setae smooth. Six lateral setae on sixth segment biarticulated at base (inserted on small pseudojoint); all other setae uniarticulated and without breaking planes. Length ratio of antennular segments, from proximal segment and along caudal margin, 1: 1: 0.3: 0.3: 0.3: 1.
Antenna (Fig. 8 E) composed of coxa, allobasis (fused basis and first endopodal segment), one-segmented endopod and one-segmented exopod, although ancestral suture between basis and first endopodal segment visible partly on anterior surface. Coxa short, unarmed and unornamented. Allobasis 2.3 times as long as coxa and about 1.6 times as long as wide, ornamented with several large spinules along inner margin proximally, unarmed. Endopod about three times as long as wide and nearly 1.4 times as long as allobasis, with two surface frills subdistally, armed laterally with two strongly pinnate spines flanking thin seta; apical armature consisting of five geniculate setae, strongest one fused basally to additional smaller seta; smallest seta smooth and slender; strongest seta about 0.8 times as long as longest geniculate seta, ornamented with large spinules around area of geniculation; other geniculate setae smooth and strong; ornamentation consisting of seven extremely large spinules on ventral surface, in groups of two, two, and three. Exopod slightly longer than coxa, with narrow basal part and somewhat wider distal part; unornamented; with one lateral (although inserted close to distal margin) and two apical strong and unipinnate setae; dorsal (outer) apical seta longest, 1.2 times as long as ventral apical seta, about 1.9 times as long as lateral seta, and 1.7 times as long as exopod.
Labrum (Fig. 9 B) large compared with cephalothorax, trapezoidal, rigidly sclerotized, with wide and straight cutting edge, ornamented subapically and apically with continuous row of strong spinules.
Paragnaths not mounted in satisfactory position to allow independent drawing or proper observation.
Mandibula (Fig. 9 C) with narrow cutting edge on elongated coxa, with three bicuspidate strong ventral teeth, two unicuspidate strong teeth, and single dorsal unipinnate seta. Palp uniramous, comprising basis and onesegmented endopod. Basis with slightly inflated distal part, about 2.5 times as long as wide, with single strong and distally unipinnate inner seta, ornamented with longitudinal row of long and slender spinules along dorsal margin. Endopod very small, unornamented, about 0.3 times as long as basis and 1.1 times as long as wide; with five slender and smooth apical setae.
Maxillula (Fig. 9 D) with large praecoxa, ornamented with several spinules on outer margin distally; arthrite rectangular, unornamented, with two anterior surface setae, three lateral, and four apical elements (probably three spines and one seta); dorsalmost of apical elements straight and with slender spinules along dorsal margin; ventralmost element smooth and curved; second element from ventral side strongest and longest, with crown of spinules distally; third element from ventral side also very strong, bicuspidate. Coxal endite much shorter than praecoxal arthrite or basis, armed apically (on inner margin) with one stout bipinnate element, and another smooth and slender seta. Basis significantly shorter than praecoxal arthrite but more than twice as long as coxal endite, with four setae apically and subapically; dorsalmost seta bipinnate, others smooth. Endopod represented by minute but distinct segment, with single bipinnate slender seta apically.
Maxilla (Fig. 9 E) ornamented with row of long spinules along outer margin of syncoxa, and another shorter row of smaller spinules on anterior surface; opening of maxillary gland clearly visible on posterior surface. Proximal endite of syncoxa well developed, although not strongly sclerotized, with characteristically inflated ventral part; unornamented; with single apical setae, which fused at base to endite, wide, soft, and distally plumose. Distal endite of syncoxa cylindrical, well sclerotised and highly mobile, armed apically with one strong bipinnate seta, and two smooth and sleder setae; smooth setae of subequal length, only slightly longer than pinnate seta, and 2.3 times as long as endite. Basis drawn out into long claw, with shorter spiniform and curved seta at base, ornamented with minute spinules along convex margin. Endopod represented by minute but distinct square segment, with two long and smooth apical setae of subequal length; enopodal setae about 1.5 times as long as basal seta, but all reaching distal tip of basal claw.
Maxilliped (Fig. 8 E) with short and stout syncoxa, ornamented with arched row of spinules on inner margin, and with two setae subapically; inner syncoxal seta bipinnate, 1.1 times as long as syncoxa, and 3.2 times as long as outer unipinnate seta. Basis twice as long as wide and 1.1 times as long as syncoxa, unarmed, ornamented with short longitudinal row of slender spinules along inner margin proximally, as well as with two short rows of spinules on outer margin (one at 1/3, other at 2/3). Endopod represented by long curved claw, about 1.3 times as long as basis, ornamented with row of spinules along concave side distally, accompanied at base by thin smooth and short seta.
All swimming legs (Fig. 9 F, G, H, I) of similar size and short in comparison to body length, composed of small triangular and unarmed praecoxa, large rectangular and unarmed coxa, shorter and nearly pentagonal basis, slender three-segmented exopod, also slender and three-segmented endopod; each leg joined to their pair on opposite side of body by simple quadriform intercoxal sclerite.
First swimming leg (Fig. 9 F) with smooth and short intercoxal sclerite, its distal margin wide and slightly concave. Praecoxa short and triangular, ornamented with row of small spinules on anterior surface along distal margin. Coxa twice as wide as long, ornamented with long spinules along outer and inner margins, additionally with two short transverse rows of spinules on anterior surface close to outer margin (one proximal and one distal). Basis with one long and not very strong bipinnate spine on outer corner, and one strong spine on inner distal corner, which ornamented with large outer spinules; ornamentation consists of short rows of large spinules at base of each spine, as well as distal row of spinules between exopod and endopod, two rows of slender spinules on inner margin, and cuticular pore on anterior surface close to outer spine. Exopod with all segments of similar length, each about 1.8 times as long as wide and ornamented with spinules along both inner and outer margins (those on outer margin very strong and long, especially on first and second segment); first two segments with single strong and finely bipinnate spine on outer distal corner, each also with setule near distal tip; third segment with three strong and finely bipinnate spines on outer margin (although shorter than those on first and second segment) and two bipinnate setae apically; outer apical seta geniculate and with shorter spinules along outer margin; inner apical seta slender and with long spinules on both margins. Endopod slightly geniculate and 1.1 times as long as exopod; first endopodal segment about as long as first exopodal segment and 1.5 times as long as wide, ornamented with slender spinules along inner margin and strong and long spinules along outer and distal margins, with single inner seta, which about twice as long as segment, slender, and finely unipinnate distally; second segment smallest, about 1.7 times as long as wide and only 0.8 times as long as first segment, ornamented with long an strong spinules along outer and distal margins, and with single slender and bipinnate inner seta; third segment slender, about 4.4 times as long as wide and almost twice as long as second segment, armed apically with three elements; innermost apical element probably spine, strong and 0.9 times as long as third segment, unipinnate along outer margin; middle element slightly more slender and geniculate seta, nearly 2.4 times as long as outer element, bipinntae distally (with smaller spinules along outer margin); innermost element slender bipinnate seta, 1.8 times as long as outer element.
Second swimming leg (Fig. 9 G) with intercoxal sclerite ornamented with four strong spinules on anterior surface, its distal margin narrow and concave. Praecoxa small and triangular, ornamented with short row of long spinules on anterior surface along distal margin. Coxa nearly 1.7 times as wide as long, ornamented with transverse row of small spinules on anterior surface proximally, four extremely long spinules on anterior surface distally, and with long spinules along outer margin. Basis with single bipinnate and long but not very strong spine on outer corner; ornamented with spinules at base of spine, as well as with distal row of spinules between exopod and endopod, four extremely long spinules on inner margin, and cuticular pore on anterior surface close to outer spine. Exopod with all segments of about same width, third segment almost twice as long as second segment and 1.6 times as long as first segment; first two segments ornamented with strong spinules along outer margin and single pore on anterior surface at base of outer spine, with inner distall frill, each with outer bipinnate spine and inner bipinnate seta; third segment ornamented with pore near outer distal corner and spinules along outer margin, with three strong and finely bipinnate outer spines, two apical bipinnate setae, and two slender and bipinnate inner setae; outer apical seta very strong (spiniform) with spinules along outer margin much shorter than those along inner margin, about 1.4 times as long as segment, and 2.5 times as long as outer spines; inner apical seta slender, with sparse long spinules on inner side and short sparse spinules on outer side, 1.2 times as long as outer apical seta; inner setae of same length, about 0.7 times as long as third segment. Endopod straight (not geniculate) and 0.9 times as long as exopod, progressively narrower from proximal to distal end, each segment ornamented with single pore on anterior surface close to outer distal corner, and row of strong spinules along outer margin; third segment about 1.6 times as long as first or second; first two segments additionally ornamented with strong frill on inner distal corner, and with single bipinnate inner seta (that on first segment very short and spiniform, curved); third segment with one inner seta, two apical setae and one subapical outermost spine; apical setae of equal length, bipinnate, 0.9 times as long as entire endopod, about as long as inner seta, and nearly 2.7 times as long as outer spine; outer apical seta on third segment with strong spinules along outer margin and slender spinules along inner margin; inner setae on second and third segment with short spinules along inner margin, and long spinules along outer margin.
Third swimming leg (Fig. 9 H) very similar to second swimming leg, except for slender outer seta on basis and two inner setae on third endopodal segment; inner seta on first endopodal segment also short, spiniform and curved.
Fourth swimming leg (Fig. 9 I) similar to third swimming leg, except for ornamentation of coxa and basis, length of outer basal seta (shorter on fourth leg), length of inner seta on first endopodal segment, and armature of third exopodal segment. Coxa 1.8 times as long as wide, without proximal row of spinules on anterior surface, with smaller spinules in posterior row on anterior surface, and with fewer and larger spinules along outer margin. Inner spinules on basis much shorter than those on second and third legs. Third exopodal segment ornamented with two spinules on posterior surface distally, in addition to outer spinules and anterior pore; with three outer finely bipinnate spines, two apical bipinnate setae, and two inner setae (as second and third legs), but distal inner seta as strong as outer spines and longest. First endopodal segment with long and slender inner seta. Second endopodal segment with single large spinule on posterior surface, in addition to outer distal frill, anterior pore, and strong spinules along outer margin.
Fifth leg (Figs. 8 G, 9J) biramous, both legs distinct and composed of wide baseoendopod (fused basis and endopod). Baseoendopod with outer basal seta slender and unipinnate, arising from long setophore; baseoendopod ornamented with single small pore on anterior surface at base of outer seta. Endopodal lobe relatively wide, trapezoidal, extending slightly beyond proximal half of exopod, with five stout, bipinnate setae, with length ratio (from inner side), 1: 0.4: 0.4: 1.6: 0.8. Exopod about twice as long as its maximum width, ornamented with long and slender spinules along inner margin, with five setae; innermost and fourth seta from inner side bipinnate, other three setae smooth. Length ratio of five exopodal setae, from inner side, 1: 1.1: 0.7: 0.9: 0.2.
Sixth legs (Fig. 2 A) completely fused together, indistinct, forming simple operculum covering single gonopore, without any ornamentation, each with two setae and minute spine; both seta directed posteriorly; inner seta smooth, and about twice as long as outer seta, which unpinnate.
Male. Unknown.
Variability. Only three females have been collected and observed, and no variability was found except slight differences in body length. All appendages are also fully symmetrical.
Remarks. This is the first record of the genus Pseudameira Sars G.O., 1911 in Korea, and P. mago sp. nov. also has no close relatives among recent species, at least as one can judge from its morphology. The genus contains today only 15 valid species (Walter & Boxshall 2011) (note: Pseudameira kunzi Petkovski, 1956 is a junior subjective synonym of Nitokra reducta Schäfer, 1936), but it is a very loose assemblage, with hardly any closely related species, and certainly no sister species. Antennulae range from six- to eight-segmented, fifth legs vary in shape and armature, caudal rami can be short or long, and there are hardly any species with the same armature formula of the swimming legs. This was already noticed by Lang (1948, 1965) and Gee & Fleeger (1986), who provided tables with spine formulas for species known at that time.
Pseudameira mago could be distinguished at once from most congeners by its unique armature formula of second to fourth swimming legs. In such a way it can be distinguished from P. breviseta Klie, 1950, P. crassicornis Sars G.O., 1911, P. gracilis Sars G.O., 1920, P. l i m i c o l a Soyer, 1975, P. reducta Klie, 1950, P. signyensis Gee & Fleeger, 1986, and P. t r i s e t o s a Schriever, 1984 by the presence of two inner setae on the third exopodal segments of second and third swimming legs (one or none in other species). Presence of an inner seta on the first exopodal segment of the forth leg distinguishes P. m a g o from P. antennulata Schriever, 1984, P. b i r u l a i Smirnov, 1946, P. brevifurca Shen & Bai, 1956, P. fu rca ta Sars G.O., 1911, and P. minutissima Monard, 1928 (all these species lack the inner seta). Finally, the presence of only two inner setae on the third exopodal segment of the fouth leg distinguishes P. m a go from P. mixta mixta Sars G.O., 1920, P. mixta adriatica Apostolov & Petkovski, 1980, and P. perplexa Soyer, 1975 (all these have three setae instead). Unfortunately, the very limited data we have about P. reflexa (Scott T., 1894) do not allow comparison of the swimming legs armature formula, but this species differs from P. mago by an eight-segmented antennula, as well as by more elements on the fifth leg (six on the baseoendopod and seven on the exopod). Each of the above mentioned 15 species and one subspecies differs from P. mago additionally by a number of morphological characters.
Pseudameira perplexa, described by Soyer (1975) from the Mediterranean Coast of France, seems to share the greatest number of morphological characters with our new species, although many of them (particularly the swimming leg armature formula) seem to be plesiomorphic states. Both species have the innermost seta on the fifth leg baseoendopod in female longer than the next one, which may be an apomorphic feature. They differ, however, by many characters, and we will list here only some of the more prominent ones for P. perplexa: genital doublesomite with continous posterior row of spinules ventrally, antennula without spinules on the second segment, first two endopodal segments of the first swimming leg as long as the exopod, maxilliped with only one seta on the syncoxa, basis of the second swimming leg with short spinules along inner margin, setae on the first endopodal segments of the second and third legs not spiniform, third exopodal segment of the fourth swimming leg with three inner setae (as mentioned above), and outer exopodal setae on the female fifth leg very short.
Similarly long innermost seta on the fifth leg baseoendopod was reported only in P. breviseta, described from Germany by Klie (1950), but this species has six setae on the fifth leg exopod, a seven-segmented antennula, as well as a different armature of the second and third swimming legs. Spinules on the second segment of antennula have been illustrated or described so far, besides P. mago, only for P. f u rc a t a and P. brevifurca (see Lang 1948; Shen & Bai 1956). Pseudameira furcata, however, has much longer caudal rami than P. m a g o, while P. bervifurcata has a seven-segmented antennula, more robust habitus, and an unarmed inner margin of the first exopodal segment of the fourth leg. The latter species is, unfortunately, very poorly described, and the authors admitted to loosing the antenna, first swimming leg, and fifth leg (presumably during dissection). This is unfortunate, as P. brevifurca is the only other Asian representative of the genus. It was decribed from Chefoo in China (also commonly spelled as Zhifu), on the west coast of the Yellow Sea, some 400 km away from the type locality of P. m a g o. Future studies of more specimens of both species from different localities, using both molecular and morphological methods, may shead new light on the status of the genus Pseudameira in the Yellow Sea. At present, and given the current level of taxonomy in this group, there is enough evidence to consider P. brevifurca and P. mago as separate species.
Genus Proameira Lang, 1944
description: Published as part of Karanovic, Tomislav & Cho, Joo-Lae, 2012, Three new ameirid harpacticoids from Korea and first record of Proameira simplex (Crustacea: Copepoda: Ameiridae) *, pp. 91-127 in Zootaxa 3368 on pages 110-117, DOI: 10.5281/zenodo.281703