Tropodiaptomus megahyaline, Saetang & Sanoamuang & Maiphae, 2021
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publication ID |
https://doi.org/ 10.1080/00222933.2020.1843726 |
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persistent identifier |
https://treatment.plazi.org/id/EC638B21-FF94-DE2D-FE15-EF44FCE4F94D |
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treatment provided by |
Carolina |
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scientific name |
Tropodiaptomus megahyaline |
| status |
sp. nov. |
Tropodiaptomus megahyaline sp. nov.
Type locality. Rice field no . 1 near Songkhram River Basin, Bueng Kan Province, northeastern Thailand, 3 June 2019 . Plantation period . Water temperature 34.92°C, conductivity 422.2 µs cm −1, salinity 0.17, total dissolved solids 231 mg L −1, dissolved oxygen 6.07 mg L −1, pH 5.87, and water depth 10–30 cm, substrate with mud .
Other localities. (1) Rice field no . 2 near Songkhram River Basin, Bueng Kan Province, Northeastern Thailand, 3 June 2019 . Plantation period . Water temperature 35.18°C ,
conductivity 684.8 µs cm −1, salinity 0.27, total dissolved solids 373 mg L −1, dissolved oxygen 7.73 mg L −1, pH 5.99, and water depth 10–30 cm, substrate with mud. (2) A permanent pond without aquatic plants near Songkhram River Basin, Bueng Kan Province, Northeastern Thailand, 24 May 2018. Water temperature 35.12°C, conductivity 163.1 µs cm −1, salinity 0.06, total dissolved solids 89 mg L −1, dissolved oxygen 7.78 mg L −1, pH 7.31, and water depth 80–100 cm, substrate with sandy clay.
Material examined. Holotype: adult female, Thailand, Bueng Kan (rice field no. 1), 3 June 2019, PSUZC-PK2006-01 – PSUZC-PK2006-05 . Allotype. One adult male, same data as holotype, PSUZC-PK2006-06 – PSUZC-PK2006-10 . Paratypes: one adult female, Thailand, Bueng Kan (rice field no. 2), 3 June 2019, PSUZC-PK2006-11 ; one adult male, Thailand, Bueng Kan (a permanent pond), 24 May 2018, PSUZC-PK2006-12 – PSUZC-PK2006-13 .
Differential diagnosis
Tropodiaptomus megahyaline sp. nov. differs from its congeners by: antepenultimate segment of the male right antennule with straight spinous process reaching middle of next segment; basis of the male right P5 with three processes; basis of the male right and left P5 with longitudinal hyaline lamella, length about 1/3 as long as basis on the inner margin; exp-2 of the male right P5 trapezoidal, with two semicircular hyaline knobs, and one triangular process on distal outer margin of dorsal surface; inner margin of exopod of the male left P5 with the proximal part larger than the distal part.
Description of the adult female
Body ( Figure 2 View Figure 2 , 3 View Figure 3 ). Total body length ( Figure 2 View Figure 2 (a)), measured from anterior margin of rostrum to posterior margin of caudal rami, 1.1–1.5 mm (mean 1.3 mm, n = 3; 1.5 mm in holotype). Prosome with sensilla on dorsal surface, length about 2.8–3.0 times as long as urosome (including caudal rami) (mean 2.8, n = 3; 3.0 in holotype). Fourth and fifth pedigers ( Figures 2 View Figure 2 (a), Figures 3 View Figure 3 (a)) completely fused, fusion being indicated by indentation on each side. Fifth pediger ( Figure 3 View Figure 3 (a)) produced into symmetrical posterolateral wings, each distal end with posterior spine, 1 dorsal spine on inner margin of right wing and 2 dorsal spines on inner margin of left wing. Urosome 2-segmented ( Figures 2 View Figure 2 (a), Figures 3 View Figure 3 (a)). Genital double somite ( Figures 2 View Figure 2 (a), Figures 3 View Figure 3 (a–b)) symmetrical, longer than anal somite combined with caudal rami, with 2 proximally, unequal dorsolateral spines (left spine smaller than right spine). Genital area on ventral surface ( Figure 3 View Figure 3 (b)) shows opercular pad protecting gonopores, characterised by rectangular and semicircular expansions. Anal somite ( Figures 2 View Figure 2 (a), Figures 3 View Figure 3 (a–b)) about 1.0–1.2 times as long as wide (mean 1.1, n = 3; 1.2 in holotype), with 1 pair of sensilla on ventral surface ( Figure 3 View Figure 3 (b)). Caudal rami ( Figures 2 View Figure 2 (a), Figures 3 View Figure 3 (a)) symmetrical, both sides parallel, about 1.6–1.7 times as long as wide (mean 1.6, n = 3; 1.7 in holotype), with setules on outer and inner margins. Each ramus with 6 setae.
Rostrum ( Figure 2 View Figure 2 (d)). Two rostral elements on anterior margin, with suture in the middle.
A1 ( Figure 2 View Figure 2 (b–c)). Symmetrical, 25-segmented, reaching beyond the end of caudal rami. Armature formula [number of setae + aesthetasc (ae) + spine (s)] of each segment
as follows: 1+ ae, 3+ ae, 1+ ae, 1, 1+ ae, 1, 1+ ae, 1 + s, 2+ ae, 1, 1, 1+ ae+s, 1, 1+ ae, 1, 1 + ae, 1, 1, 1+ ae, 1, 1, 2, 2, 2, 5+ ae.
A2 ( Figure 4 View Figure 4 (a)). Coxa with 1 inner seta on distal corner. Basis with 2 inner setae on distal corner. Exopod 7-segmented, exp-1–6 with 1, 3, 1, 1, 1, and 1 inner setae, respectively, and exp-7 with 1 inner and 3 apical setae. Endopod 2-segmented, enp-1 with 2 inner setae and 1 row of outer spinules, enp-2 with 9 inner and 7 apical setae; with 1 row of outer spinules.
Mandible ( Figure 4 View Figure 4 (b)). Coxa with 8 strongly chitinised teeth and 1 unipinnate seta on gnathobase. Basis with 4 inner setae. Exopod 4-segmented with 1, 1, 1, and 3 setae,
respectively. Endopod 2-segmented, enp-1 with 4 inner setae, enp-2 with 9 apical setae and two horizontal rows of outer spinules.
Maxillule ( Figure 4 View Figure 4 (c)). Precoxal arthrite with 4 plumose setae and 11 bipinnate spines. Coxal endite with 4 plumose setae and coxal epidite with 7 plumose setae and 2 bipinnate spines. Basis with 2 endites; the proximal with 4 plumose setae and the distal with 8 plumose setae, and basal exite with 1 smooth seta. Endopod 1-segmented with 4 plumose setae. Exopod 1-segmented with 6 plumose setae, 1 longitudinal row of inner setules on distal margin, and 1 horizontal row of outer setules.
Maxilla ( Figure 4 View Figure 4 (d)). Proximal praecoxal endite with 4 setae, distal praecoxal endite with 2 setae. Proximal and distal coxal endites with 3 setae. Allobasis protruding into endite with 4 setae. Endopod reduced to 2 segments, each with 3 setae.
Maxilliped ( Figure 4 View Figure 4 (e)). Praecoxa completely fused to coxa; endites with 1, 2, 3, and 3 setae, respectively. Distal corner of coxa produced into rounded lobe with spinules on outer margin. Basis with 3 setae on distal third and 1 row of setules proximally. Endopod 6-segmented; with 2, 3, 2, 2, 1 + 1, and 4 setae, respectively.
P1 ( Figure 5 View Figure 5 (a)). Intercoxal sclerite naked. Coxa with 1 inner plumose seta. Basis with setules close to outer margin on dorsal surface. Rami with 3-segmented exopod and 2- segmented endopod; endopod reaching proximal of exp-3. Exp-1 with 1 outer bipinnate spine, 1 inner plumose seta, and 1 longitudinal row of inner setules. Exp-2 with 1 inner plumose seta and 1 longitudinal row of outer setules. Exp-3 with 1 outer bipinnate spine, two apical elements (outer element: 1 spiniform seta with outer spinules and inner setules; inner element: 1 plumose seta), 3 inner plumose setae, 1 longitudinal row of outer setules, and 1 row of spinules close to distal end on dorsal surface. Enp-1 with 1 inner plumose seta. Enp-2 with 1 outer plumose seta, 2 apical plumose setae, 3 inner plumose setae, and 1 longitudinal row of outer and inner setules.
P2 ( Figure 5 View Figure 5 (b)). Intercoxal sclerite naked. Coxa with 1 inner plumose seta. Basis without seta. Both rami 3-segmented; endopod reaching proximal of exp-3. Exp-1 with 1 outer bipinnate spine, 1 inner plumose seta, and 1 longitudinal row of inner setules. Exp-2 with 1 outer bipinnate spine, 1 inner plumose seta, and 1 longitudinal row of outer and inner setules. Exp-3 with 1 outer bipinnate spine, 2 apical elements (outer element: 1 spiniform seta with outer spinules and inner setules; inner element: 1 plumose seta), 4 inner plumose setae, 1 longitudinal row of outer and inner setules, and 1 row of outer spinules close to distal end on dorsal surface. Enp-1 with 1 inner plumose seta, and 1 longitudinal row of outer setules. Enp-2 with 2 inner plumose setae, 1 longitudinal row of outer and inner setules, and Schmeil’s organ. Enp-3 with 2 outer plumose setae, 2 apical plumose setae, 3 inner plumose setae, and 1 longitudinal row of outer and inner setules, and 1 row of outer spinules close to distal end on dorsal surface.
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