Bryocamptus (Bryocamptus) abramovae, Novikov & Sharafutdinova & Chertoprud, 2023

Novikov, Aleksandr, Sharafutdinova, Dayana & Chertoprud, Elena, 2023, Two new species of Bryocamptus (Copepoda, Harpacticoida, Canthocamptidae) from the Russian Arctic and comparison with Bryocamptus minutus (Claus, 1863), ZooKeys 1138, pp. 89-141 : 89

Bryocamptus (Bryocamptus) abramovae sp. nov.

Figs 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18

Bryocamptus sp. 2 - Novikov et al. 2021: 271.

Bryocamptus sp. 1 - Novikov and Sharafutdinova 2022: 34.

Material.

Holotype: Russia • ♀ dissected on two slides; Lena River Delta , Samoylov Island, Ruiba Lake; 72.373003°N, 126.489429°E; depth 1-1.5 m; 23 Aug. 2019; A. Novikov leg; BP 547/1-a, BP 547/1-b . Allotype: Russia • ♂ dissected on one slide; collection data as for holotype; BP 547/2 . Paratypes: 5 ♀ and 3 ♂ undissected, preserved in 4% formalin; collection data as for holotype; BP 547/4 .

Additional material.

Russia • 9 ♀♀ and 6 ♂♂ undissected; Lena River Delta , Jangylakh Sise Island, large nameless lake; 72.517921°N, 125.281147°E; 7 Aug. 2019; A. Novikov leg; retained in the collection of the first author .

Russia • 2 ♀♀ undissected; Lena River Delta , Baron Island, small thermokarst lake; 72.550939°N, 126.93597°E; 8 Aug. 2019; A. Novikov leg; retained in the collection of the first author .

Russia • 3 ♀♀ and 1 ♂ undissected; Lena River Delta , Kurungnah Sise Island, Krugloe Lake; 72.468859°N, 126.265658°E; 21 Aug. 2019; A. Novikov leg; retained in the collection of the first author

Russia • 4 ♀♀ and 2 ♂♂ undissected; Vrangel Island , large nameless lake; 70.954443°N, 179.567387°E; 26 Aug. 2021; A. Novichkova leg: retained in the collection of the first author .

Description.

Female (based on holotype and paratypes). Body subcylindrical (Fig. 10A ). Total body length from anterior margin of rostrum to posterior margin of caudal rami: 586 µm (n = 1). Cephalothorax (Fig. 10B, C ; Appendix 1), wider as remaining somites, length 152 µm, largest width 113 µm. Naupliar eye red. Rostrum (Fig. 10D ) small, fused with cephalothorax, with rounded end, with one pair of sensillae and pore located proximal to sensillae. Posterior margin of cephalothorax and all pedigerous somites smooth.

Cephalothorax (Fig. 10B, C ; Appendix 1) with dumbbell-shaped dorsal window, seven pairs of pores, seven pairs of sensillae of central group (group C), eight pairs of sensillae of marginal group (group P) and 13 pairs of ungrouped sensillae (in Table 4 and in Appendix 1 marked as L). Second pedigerous somite with lateral windows, dorsal unpaired pore, lateral pair of pores and six pairs of sensillae. Third pedigerous somite with dorsal unpaired pore and six pairs of sensillae. Fourth pedigerous somite with dorsal unpaired pore and five pairs of sensillae. Fifth pedigerous somite with three pairs of sensillae.

Abdomen (Fig. 11A-C ) consisting of genital-double somite, two free abdominal somites and anal somite with caudal rami. All somites except anal somite slightly wavy posterior margin, on surface with spinular rows. Genital-double somite consists of last thoracic somite and first abdominal somite; wider than long; anterior part with two pairs of sensillae, dorsal unpaired pore, ventro-lateral row of spinules; posterior part with three pairs of sensillae, pairs of ventral and lateral pores and lateral rows of spinules.

P6 (Fig. 11C ) fused with somite with one pinnate and one naked setae. Genital field (Fig. 11C ) short, laterally with eight-pore sieves; copulatory pore located medially, copulatory duct chitinised with two additional tubes, extending proximally to pair of labyrinthic rounded ducts and one chitinised unpaired duct.

Second and third abdominal somites as in B. minutus . Anal somite with one pair of sensillae, ventral pair of large pores, lateral pair of pores and lateral spinules. Anal operculum semilunar, with seven short bifid spinules.

Caudal rami (Fig. 11A-D ). Length/width ratio 1.6, with three ventral pores; with rows of spinules on ventral and dorsal side at base of seta VI and rows spinules at base of setae II and III. Seta I small, located near seta II. Apical seta IV (Fig. 11D ) bipinnate, without "helle Stelle". Apical seta V long, bipinnate, with "helle Stelle". Seta VI with wide base (Fig. 11C ). Seta VII triarticulated (Fig. 11B ).

Antennule (Fig. 12A ) similar to that of Bryocamptus minutus . Differences expressed in more elongated segments, especially 3th and 4th segments; one of setae on segment 2 pinnate. Armature formula: 1-[1],2-[9],3-[5],4-[1+(1+ae)],5-[1],6-[3],7-[2],8-[5+acr].

Antenna (Fig. 12B ) similar to that of Bryocamptus minutus . Allobasis and free endopodal segment slightly more elongated. Inner spinular row on coxa with extremely long spinules. Allobasis with proximal outer spinular row, basal seta pinnate.

Labrum (Fig. 12C ) similar to that of Bryocamptus minutus , but without semicircular spinular row on inner side.

Mandible (Fig. 13A, B ) similar to that of Bryocamptus minutus . The palp is shortened.

Paragnaths (Fig. 12D ) similar to that of Bryocamptus minutus , with only three lateral groups of spinules and with a more well-defined pocket.

Maxillule (Fig. 13C ) similar to that of Bryocamptus minutus . Basis with two groups of spinules.

Maxilla (Fig. 13D ) as in Bryocamptus minutus , only with slight differences in length and armature of setae.

Maxilliped (Fig. 14A ) similar to that of Bryocamptus minutus . Differences are only in shorter syncoxa and basis.

Cuticular process between maxillipeds and P1 (Fig. 14B, C ) in height approximately same as in length, with long spinules, seven spinules on each side. Spinules on posterior margin.

P1 (Fig. 14D ; Table 2 ) similar to that of Bryocamptus minutus . Basis without inner spinules. First exopodal segment with row of small spinules on anterior side. First endopodal segment reaching end of second exopodal segment. First and second endopodal segments with smooth inner side. Differences also noticeable in shorter exopodal and endopodal segments and larger spinules on coxa and basis.

P2 (Fig. 14E ; Table 2 ). Praecoxa with row of spinules. Coxa with one lateral row of large spinules, two anterior rows of large spinules and four anterior rows of small spinules. Intercoxal sclerite naked. Basis with proximal pore, inner group of long spinules, rows of spinules at base of endopod and exopod; with outer spine. All endopodal and exopodal segments with outer spinules. Exopod three-segmented; first exopodal segment with outer spinulose spine, apically with frill; second segment with outer spinulose spine, inner pectinate seta, inner slender spinules and apical frill; third segment with three outer spinulose spines, two apical setae and one inner pectinate seta. Endopod three-segmented; first and second segments with inner seta; third segment with outer spinulose spine, two apical pinnate setae and one inner pectinate seta.

P3 (Fig. 15A ; Table 2 ). Praecoxa with spinular row. Coxa with one lateral row of large spinules, two anterior rows of large spinules and four anterior rows of small spinules. Intercoxal sclerite without spinules. Basis with outer seta, proximal pore, inner group of long spinules and rows of spinules at base of endopod and exopod. Exopod three-segmented; first exopodal segment with outer spinulose spine, outer spinules, apically with frill; second segment with outer spinulose spine, outer spinules, inner pectinate seta, inner slender spinules and apical frill; third segment with three outer spinulose spines, two apical setae and two inner pectinate setae. Endopod three-segmented; first and second segments with inner seta, second segment with outer spinules; third segment with outer spinules, outer spinulose spine, two apical pinnate setae and two inner pectinate setae.

P4 (Fig. 15B ; Table 2 ). Praecoxa with spinular row. Coxa with one lateral row of large spinules, two anterior rows of large spinules and four anterior rows of small spinules. Basis with outer seta, proximal pore, rows of spinules at base of endopod and exopod. Exopod three-segmented; first exopodal segment with outer spinulose spine, outer spinules, apically with frill; second segment with outer spinulose spine, outer spinules, inner pectinate seta, inner slender spinules and apical frill; third segment with two outer spinulose spines, two apical setae and two inner pectinate setae. Endopod two-segmented; first segment with inner pectinate seta, second segment with outer spinules, outer spinulose spine, apical spiniform spinulose seta, apical pinnate seta and two inner pectinate setae.

P5 (Fig. 15C ) with separate right and left baseoendopods. Baseoendopod reaching ~ 2/3 of exopodal segment; with four pores, spinular row at base of outer seta; outer seta of basis pinnate, long. Endopodal lobe with four long bipinnate setae and one short bipinnate seta V; with small process that may be pore between setae III and IV. Exopod inner thin pinnate seta, long apical pinnate seta, naked subapical seta and two pinnate outer setae.

Male. Sexual dimorphism expressed in the antennule, P2-P6, genital segmentation and ornamentation, shape of caudal rami. Cephalothorax and thoracic somites as in female. P6 (Fig. 16B ) two asymmetric flaps fused to the somite, with three naked setae. Differences from female in abdomen structure as follows (Fig. 16A, B ): first abdominal somite free; first to third abdominal somites with spinular row encircling somite ventrally and laterally; anal somite with ventral spinule and without lateral spinules; caudal rami without ventral spinules; seta IV with "helle Stelle".

Antennule (Fig. 17A, B ) 10-segmented, haplocer with geniculation between segments 7 and 8. Segments 1, 3, 4, 5, 6, 9, and 10 almost like in B. minutus , but more elongated. Segment 2 with small pore on anterior side. Segment 7 with articular plate, with one filiform seta, one small caudate seta and with two modified laminar setae. Segment 8 with proximal short dentate plate and two modified laminar setae. Armature formula: 1-[1],2-[9],3-[8],4-[2],5-[6+(1+ae)],6-[2],7-[2+2 modified],8-[2 modified],9-[1],10-[7+acr].

P2 (Fig. 18A ) as in female, except endopod. Endopod two-segmented. First segment with inner seta. Second segment with notch on distal outer margin, outer spinules, two apical pinnate slender setae and two inner pectinate setae.

P3 (Fig. 18B-D ): praecoxa, coxa, intercoxal sclerite as in female. Basis as in female, but with larger inner process. Exopod as in female, but third segment with pore. Endopod three-segmented. First endopodal segment with strong seta. Second endopodal segment with posterior thin seta and long apophysis with double tip. Third segment with two small inner setae and two apical pinnate setae.

P4 (Fig. 18E ): praecoxa, coxa, intercoxal sclerite, basis, exopod as in female. Endopod two-segmented; first segment short, unarmed; second segment with outer spinules, spinulose spine, outer apical spiniform spinulose seta and inner apical bipinnate seta.

P5 (Fig. 17C ) right and left fused medially. Baseoendopod with three pairs of pores, outer spinule and outer long pinnate seta; endopodal lobe with two strong spinulose apical spines. Exopod with spinule on anterior surface, two equal length outer setae, naked outer subapical seta, long apical spinulose seta, one inner spinulose seta and one long inner pectinate seta with long setules.

Variability.

Individuals with two outer spines on the third exopodal segments of P2-P4 were found.

Etymology.

This species is named after Ekaterina Abramova, teacher and mentor of the first author.

Remarks.

The species is well distinguished from other species of the B. minutus group by the presence of only five setae on the endopodal lobe of females P5 and by simple caudal rami with unmodified setae.

Figures

Figure 10. Bryocamptus abramovae sp. nov., female A habitus, lateral B cephalothorax and thoracic somites, dorsal C cephalothorax and thoracic somites, lateral D rostrum. Scale bars: 50 µm (A-C); 5 µm (D).

Figure 11. Bryocamptus abramovae sp. nov., female A abdomen, dorsal B abdomen, lateral C abdomen, ventral D caudal setae, dorsal. Scale bar: 50 µm.

Figure 12. Bryocamptus abramovae sp. nov., female A antennule B antenna C labrum, posterior (black dots is bases of spinules) D paragnaths, anterior. Scale bars: 25 µm (A); 10 µm (B-D).

Figure 13. Bryocamptus abramovae sp. nov., female A mandible B scheme of teeth of mandibular gnathobase C maxillule D maxilla. Scale bar: 10 µm.

Figure 14. Bryocamptus abramovae sp. nov., female A maxilliped B cuticular process between maxillipeds and P 1, ventral C cuticular process between maxillipeds and P 1, lateral D P 1, anterior E P 2, anterior. Scale bars: 10 µm (A); 5 µm (B, C); 25 µm (D, E).

Figure 15. Bryocamptus abramovae sp. nov., female A P 3, anterior B P 4, anterior C P 5, anterior. Scale bars: 25 µm.

Figure 16. Bryocamptus abramovae sp. nov., male A abdomen, dorsal B abdomen, ventral. Scale bar: 50 µm.

Figure 17. Bryocamptus abramovae sp. nov., male A antennule, anterior B antennule, dorsal C P 5, anterior. Scale bars: 10 µm.

Figure 18. Bryocamptus abramovae sp. nov., male A P 2, anterior B P 3, anterior C P 3 endopod, anterior D P 3 endopod, inner view E P 4, anterior. Scale bars: 25 µm (A, B, E); 10 µm (C, D).