Moina heilongjiangensis, Bi & Wei & Deng & Blair & Hu & Yin, 2025

Bi, Ran, Wei, Jie, Deng, Zhixiong, Blair, David, Hu, Wei & Yin, Mingbo, 2025, Moina heilongjiangensis sp. nov. (Crustacea, Cladocera) from the northeast of China, Zoosystematics and Evolution 101 (3), pp. 1325-1337 : 1325-1337

publication ID	https://doi.org/10.3897/zse.101.150242
publication LSID	lsid:zoobank.org:pub:2C9609FE-67F0-4B36-BEE3-13C5E4AAE029
DOI	https://doi.org/10.5281/zenodo.16681535
persistent identifier	https://treatment.plazi.org/id/AAD8F194-99F3-5B1B-BF68-67D16115E652
treatment provided by	Zoosystematics and Evolution by Pensoft
scientific name	Moina heilongjiangensis
status	sp. nov.

Treatment

Moina heilongjiangensis sp. nov.

Figs 1 View Figure 1 , 2 View Figure 2 , 3 View Figure 3

Etymology.

The species is named after Heilongjiang, the province in China where the new species was first discovered.

Type locality.

Xidahai GoogleMaps , Daqing, Heilongjiang Province, China (a lake located at 46.03°N, 124.36°E). Xidahai is an inland brackish lake, with a length of 8.4 km and an average width of 3.1 km, covering an area of 26.5 km 2. The maximum depth is 3.5 m, with an average depth of 2.3 m. The annual mean temperature of the lake is 3.4 ° C, with an average temperature of 23.1 ° C in July ( Wang and Dou 1998).

Holotype.

An adult parthenogenetic female in 95 % ethanol was deposited at the Preservation of Zooplankton Collection at Fudan University, Shanghai, China, 1.17 mm in length, from Xidahai , accession number: MHXDH 2023090101 . GoogleMaps

Allotype.

An adult male in 95 % ethanol was deposited at the Preservation of Zooplankton Collection at Fudan University, China, 1.02 mm in length, from Xidahai , accession number: MHXDH 2023090301 . GoogleMaps

Paratypes.

All paratypes in 95 % ethanol were deposited at the Preservation of Zooplankton Collection at Fudan University, China. Five adult parthenogenetic females, 1.14–1.35 mm in length, from Xidahai. Four ephippial females, 1.08–1.31 mm in length, from Xidahai, China. Four adult males, 1.00– 1.18 mm in length, from Xidahai, China, accession numbers: adult parthenogenetic females: MHXDH 2023090102 - MHXDH 2023090106, ephippial females: MHXDH 2023090201 - MHXDH 2023090204, adult males: MHXDH 2023090302 - MHXDH 2023090305.

Morphological description.

Parthenogenetic female (Figs 1 View Figure 1 , 2 View Figure 2 ). Body ovoid in lateral view, shape typical of genus. Relatively large, body height / length ratio about 0.46–0.63 for adults, depending on development of brood chamber. Dorsal margin of valve slightly higher than head level. Anterodorsal angle rounded, posteroventral angle broadly rounded (Fig. 1 A View Figure 1 ). Ventral margin of valve rounded, with 40–45 marginal setae (Fig. 1 A, H View Figure 1 ). Surface of head and valve lacking a cover of fine hair.

Head ovoid-round, lacking supra-ocular depression and dorsal head pore (Fig. 1 A View Figure 1 ). Compound eye small, ocellus absent.

Labrum medium length, with fleshy main body, straight ventral margin (Fig. 1 E View Figure 1 ). Short setulae on inner ventral portion and long setulae on labral plate.

Valve ovoid, without fine hairs (Fig. 1 A View Figure 1 ). Setae relatively long on anterior portion of ventral margin, shorter on posterior portion (Fig. 1 H View Figure 1 ).

Postabdomen typical of genus, conically narrowing distally (Fig. 1 F, G View Figure 1 ). Postabdomen with curved ventral margin; preanal margin longer than anal, both with rows of short hairs; postanal region bears row of 7–11 large, triangular, feathered teeth.

Postabdominal claw relatively large, slightly curved, with pointed apex (Fig. 1 F, G View Figure 1 ); dorsal side with two pectens, proximal ventral pecten well-developed, formed of short teeth; distal pecten formed of shorter fine setulae; ventral margin of claw with several denticles on root edge. Tooth near anterior portion of postabdominal claw bident, with branches unequal in length.

Antenna I long, almost straight (Fig. 1 B, C View Figure 1 ). Antennular body with transverse long fine hairs and numerous minute denticles. One additional setule on antenna I. Antennular sensory seta relatively short, implanted at middle of antennular body. Six aesthetascs short, sub-equal in size (Fig. 1 C View Figure 1 ).

Antenna II typical of moinids (Fig. 1 D View Figure 1 ). Coxa with short setulated sensory setae and two elongated antennal branches. Basal segment robust, with numerous transverse rows of fine hairs; short spine on outer surface between exopods. One exopod with four cylindrical segments and one endopod with three cylindrical segments, covered by transverse rows of denticles and hairs. Antennal formula: setae 0-0 - 1 - 3 / 1 - 1 - 3; spines 0-1 - 0 - 1 / 0 - 0 - 1. Setae of both antennal branches long, with long, fine setulae. Spine on second exopod segment short, slightly shorter than apical exopod and endopod spines.

Limb I with elongated limb body (Fig. 2 A View Figure 2 ). Endite 5 with one anterior seta (Fig. 2 A, B View Figure 2 : 1) covered by short setulae and two posterior setae (Fig. 2 A View Figure 2 : a-b). All posterior setae on limb I covered by short, dense setulae. Endite 4 with one anterior seta (Fig. 2 A, B View Figure 2 : 2) and a single posterior seta (Fig. 2 A View Figure 2 : c). Endite 3 without an anterior seta, but with two posterior setae (Fig. 2 A View Figure 2 : d, e). Endite 2 with three posterior setae (Fig. 2 A View Figure 2 : f – h). Two ejector hooks of different lengths (Fig. 2 A View Figure 2 : ejh).

Limb II with large ovoid epipodite (Fig. 2 C View Figure 2 : epp) and elongated exopodite bearing a single seta (Fig. 2 C View Figure 2 ). Endite 5 with a slender soft seta and a reduced shorter soft seta (Fig. 2 C View Figure 2 : a, b); endite 4 with a single soft seta (Fig. 2 C View Figure 2 : c); endite 3 with a soft seta (Fig. 2 C View Figure 2 : d); endite 2 with a small soft seta implanted anteriorly on limb body and one slender posterior soft seta (Fig. 2 C View Figure 2 : e, f); gnathobase (endite 1) with four anterior setae (Fig. 2 C View Figure 2 : 1–4) and about 15 posterior setae (Fig. 2 C View Figure 2 : a – o). Seta 1 elongated, with relatively long setulae. Setae 2, 3, and 4 significantly shorter than seta 1, with short setulae located on basal corner of gnathobase (Fig. 2 C View Figure 2 ).

Limb III with ovoid epipodite (Fig. 2 D View Figure 2 : epp). Exopodite (Fig. 2 D View Figure 2 : ext) almost rounded, with four distal and two lateral setae (Fig. 2 D View Figure 2 ). Inner distal portion of limb with two endites: first endite bearing three posterior (Fig. 2 D, E View Figure 2 : 2–4) and ten anterior setae (Fig. 2 D – F View Figure 2 : a – j); second endite bearing two anterior setae (Fig. 2 D, F View Figure 2 : 1, 5) and six anterior (Fig. 2 E, F View Figure 2 : k – p) setae. Large lobe (gnathobase) on inner margin of limb, with numerous setae (Fig. 2 D, F View Figure 2 ).

Limb IV with small ovoid epipodite (Fig. 2 G View Figure 2 : epp). Exopodite (Fig. 2 G View Figure 2 : ext) rounded, relatively large, as in limb III, with four distal and two lateral setae. Inner distal portion with two endites: first endite with one anterior seta (Fig. 2 G View Figure 2 : 1) and one posterior seta (Fig. 2 G View Figure 2 : a); and second endite with one anterior seta (Fig. 2 G View Figure 2 : 2) and two posterior setae (Fig. 2 G View Figure 2 : b, c). Gnathobasic filter plate in inner portion, with numerous setae.

Limb V small oval pre-epipodite (Fig. 2 H View Figure 2 ) beside large ovoid epipodite (Fig. 2 H View Figure 2 : epp). Oval exopodite (Fig. 2 H View Figure 2 : ext) with one large distal and one small seta nearly half length of large seta. Inner limb portion one setulated ovoid lobe and two unequal plumose setae (Fig. 2 H View Figure 2 : 1–2).

Ephippial female (Fig. 3 A View Figure 3 ). Morphology as in parthenogenetic female, but with thickened dorsal ridge of valves and gray ephippium containing two resting eggs. Shed ephippium 1.6 as long as wide, with chitinous plate of small polygons. Elongated protuberances with smooth edges in ventral portion and anastomosing lines in posterior portion of ephippium.

Male (Fig. 3 B – J View Figure 3 ). Body ovoid, more elongated than in female; body height / length ratio about 0.46. Dorsal margin of valve slightly higher than cephalic side (Fig. 3 B View Figure 3 ).

Head conical, more elongated than female, lacking fine hairs (Fig. 3 B View Figure 3 ). Dorsal head pore absent, ocellus absent.

Labrum similar to female, thinner (Fig. 3 C View Figure 3 ).

Valve ovoid, more elongated than female (Fig. 3 B View Figure 3 ). Anterior surface lacking fine hairs. Armature of ventral margin of valve similar to that in female. Setae relatively long on anterior portion of ventral margin, shorter on posterior portion (Fig. 3 H, I View Figure 3 ).

Postabdomen similar to that in female (Fig. 3 D View Figure 3 ). Posteroventral angle distinct. Fewer denticles laterally near claw base, with 8–10 feathered setae (Fig. 3 D, E View Figure 3 ). Gonopore open on lateral surface near claw base (Fig. 3 D View Figure 3 ). Small setae on the posteroventral shell rim ungrouped (Fig. 3 J View Figure 3 ).

Antenna I curved, significantly longer than in female, covered by fine hairs and transverse rows of minute denticles (Fig. 3 F View Figure 3 ). Three long antennular sensory setae, implanting at proximal one-third of antenna. Male seta near sensory seta, thicker but shorter. Apex with six short aesthetascs and seven thick hooks.

Limb I long scythe-like appearance, with copulatory hook (Fig. 3 G View Figure 3 ). Exopodite quite long. Stiff seta robust, with blunt tip.

Morphological remarks.

The new species can be identified by the diagnostic characters listed below (for an overview, see Table 1 View Table 1 ). Size relatively large for the genus, with adult parthenogenetic females up to 1.35 mm long. Surface of head and valves without fine hairs. Head without supra-ocular depression and without a dorsal head pore; ocellus absent. On the inner side of the valve, setulae not grouped. Basal pecten on dorsal side of postabdominal claw not prominent; distalmost tooth bident. One additional setule on antenna I. Sensory seta at the basipodite of antenna II long. Anterior stiff setae of limb I bristled. Setae on inner portion of limb II strongly different in size. Setules on stiff setae of limb III and limb IV long. Ephippium containing two resting eggs, its dorsal part with microsculpture represented by small polygons. Male with elongated body. Small setae on the posteroventral shell rim ungrouped. Antenna I long, three long antennular sensory setae, six short aesthetascs, and seven thick bisegmented hooks of similar size at the apex. Distinctive position of male seta and sensory setae on male antenna I. Thoracic limb I with very long exopodite. Stiff seta of male limb I thick, with blunt tip. The main morphological differences between M. heilongjiangensis sp. nov. and Moina species with two eggs in the ephippium are listed in Table 1 View Table 1 .

Phylogeny.

We obtained two unique COI haplotypes and four ITS- 1 sequences from two Moina individuals from Xidahai (Suppl. material 1: tables S 1, S 2). In agreement with the morphological examination (Figs 1 View Figure 1 – 3 View Figure 3 ), our COI and ITS- 1 Bayesian trees (Figs 4 View Figure 4 , 5 View Figure 5 ) revealed that the two individuals from Xidahai are distinct from all other Moina species in the Bayesian trees, forming an independent clade. This was further supported by three independent species-delimitation methods (i. e., GMYC, bPTP, and ABGD; Fig. 5 View Figure 5 ). In the ITS- 1 Bayesian tree, bPTP identified an additional lineage that was not recognized in GMYC and ABGD analyses. Additionally, the same tree showed that M. heilongjiangensis sp. nov. is located close to the M. cf. macrocopa clade, but the COI Bayesian tree suggested a closer relationship to M. cf. affinis (for which no ITS- 1 sequences are available).