Coronatella (Coronotella) rectangula (Sars, 1962)

Garibian, P. G. & Chertoprud, E. S., 2022, First records of Cladocera and Copepoda from Chukchagir Lake and its basin (Khabarovsk Territory, Far East of Russia), Arthropoda Selecta 31 (1), pp. 10-18 : 15

Coronatella (Coronotella) rectangula (Sars, 1962)

Fig. 2 h–l .

PARTHENOGENETIC FEMALE. Length of examined individual 0.32 mm, height 0.21 mm. Body ( Fig. 3 h ) ovoid, short. Maximum height at the middle. Dorsal and posterior margin of valves convex, ventral margin slightly convex. Posterior margin rounded, anterior margin weakly straight. Head with a short rostrum, without a dorsal keel. Valves with weakly developed longitudinal lines in postero-ventral and postero-dorsal portion ( Fig. 3 h–i ). Postero-ventral angle without denticles ( Fig. 3 i ). Postabdomen ( Fig. 3 j ) short, dorsal margin convex, ventral margin slightly straight. Lateral portion with rows of clustered setae. Postanal margin with with well-developed marginal denticles, anal margin weakly convex, preanal margin slightly straight. Postabdomenal claw long with long basal spine. Limb I with IDL bearing two setae, armed with long slender spines, ODL with one long seta ( Fig. 3 k–l ).

COMMENTS. Common species in South-East Asia [ Sinev, 2016] and Russian Far East. We supposed to found Coronatella trachystriata (Chen, Zhang et Liu, 1994) in Chukchgir Lake basin, but it was not found. The Bolon Lake basin seems to be the northeast location for this species.

C. BIODIVERSITY ANALYSIS

Our analysis revealed that the copepods are wellstudied taxonomically — both sample-based rarefaction curves and the best species richness estimator reached the same plateau at 14 taxa ( Fig. 4 b ). In contrast, neither the sample-based rarefaction curves nor the best species richness estimator reached a plateau for the Cladocera ( Fig. 4 a ). Therefore, the cladoceran biodiversity is still inadequately studied in this region.

Figures

Fig. 2. Parthenogenetic females of Camptocercus fennicus (a–h) from Chukchagir Lake, 300 m from mouth of the Bikkitckan River: a — lateral view; b — labrum; c–d — postero-ventral margin of valves; e–f — postabdomen and postabdominal claw; g–h — IDL of limb I and limb I; C. lilljeborgi (i–n) from Chukchagir Lake, Tavckit Bay apex part: i — lateral view; j — head; k — postero-ventral margin of valves; l, m — postabdomen and postabdominal claw; n — limb I. Scale bars: 0.1 mm. Рис. 2. Партеногенетические самки Camptocercus fennicus (a–h) иЗ оЗера Чукчагирское, 300 м от устьЯ реки Биккиткан: a — вид сбоку; b – лЯбрум; c–d — Задне-нижний край створки. e–f — постабдомен и постабдоминальный коготь; g–h — внеШнЯЯ дистальнаЯ долЯ торакопода I и торакопод I; C. lilljeborgi (i–n) иЗ оЗера Чукчагирское, Залив Тавкит кутоваЯ часть: I — вид сбоку; b — голова; k — Задне-нижний край створки; l, m — постабдомен и постабдоминальный коготь; n — торакопод I. МасШтабнаЯ линейка: 0,1 мм.

Fig. 3. Parthenogenetic females of Biapertura sibirica (a–g) from Chukchagir Lake, 300 m from mouth of the Bikkitckan River: a — lateral view; b — posterior portion of head shield; c–d — postero-ventral margin of valves; e — postabdomen; f–g — limb I and IDL of limb I; Coronatella rectangula (h–l) from Chukchagir Lake, 300 m from mouth of the Bikkitckan River: h — lateral view; i — posteroventral margin of valves; j — postabdomen; k–l — limb I and IDL of limb I. Scale bars: 0.1 mm. Рис. 3. Партеногенетические самки Biapertura sibirica (a–g) иЗ оЗера Чукчагирское, 300 м от устьЯ реки Биккиткан: a — вид сбоку; b — ЗаднЯЯ часть головного Щита; c–d — Задне-нижний край створки; e — постабдомен; f–g — торакопод I и внеШнЯЯ дистальнаЯ долЯ торакопода I; Coronatella rectangula (h–l) иЗ оЗера Чукчагирское, 300 м от устьЯ реки Биккиткан: h — вид сбоку; i — Задне-нижний край створки; j — постабдомен; k–l — торакопод I и внеШнЯЯ дистальнаЯ долЯ торакопода I. МасШтабнаЯ линейка: 0,1 мм.

Fig. 4. Empirical and estimated numbers of Cladocera (a), Copepoda (b) taxa. Black rhombus — sample-based rarefaction curve; red quadrates — best species richness estimator (Chao 1). Рис. 4. Эмпирическое число таксонов Cladocera (a), Copepoda (b). Черные ромбы — ЭмпирическаЯ криваЯ раЗрЯжениЯ; красные квадраты — ЭмпирическаЯ криваЯ лучШей модели оценки биораЗнообраЗиЯ (Chao 1).