Nannodiaptomus haii, Tran, Duc Luong & Brancelj, Anton, 2017

Tran, Duc Luong & Brancelj, Anton, 2017, Amended diagnosis of the genus Nannodiaptomus (Copepoda, Calanoida), based on redescription of N. phongnhaensis and description of a new species from caves in central Vietnam, Zootaxa 4221 (4), pp. 457-476 : 467-473

Nannodiaptomus haii sp. nov.

( Figs. 7–11 )

Type locality. A small siphon lake inside Hang Toi Cave (coordinates of the entrance to the cave: 17° 34' 26.4'' N, 106° 15' 15.0'' E), about 900 m from the entrance; Phong Nha-Ke Bang National Park, Quang Binh province, Central Vietnam.

Type material. Holotype (female; total length 655 µm; IEBR-COP3423; collected on 21 April 2014, by D. L. Tran); dissected and mounted in glycerol.

Allotype (male; total length 640 µm; IEBR-COP3424; collected on 21 April 2014 by D. L. Tran); dissected and mounted on slide in glycerol.

Paratypes: 3 males (IEBR-COP3425–3427), 3 females (IEBR-COP3428–3430), dissected and mounted in glycerol; collection details the same as the holotype and allotype.

The holotype, allotype and 6 paratypes deposited in the Institute of Ecology and Biological Resources ( IEBR), Hanoi, Vietnam ; 15 males and 15 females undissected, preserved in 70 % ethanol, collection details the same as the holotype; deposited at the National Institute of Biology (NIB), Ljubljana, Slovenia ; 10 males and 10 females prepared for SEM examinations. Collection details the same as the holotype.

Additional material. 40 males, 30 females (IEBR-COP-AED04.14.028), preserved in 70 % ethanol, deposited at the IEBR, Vietnam. Collection details the same as the holotype.

Description of female. Total length (without caudal setae) 610–680 µm, mean 655 µm (N= 25). Mean prosome length: 476 µm; mean urosome length: 196 µm; prosome/urosome ratio 2.4 (N= 10). Preserved specimens colourless and eyeless. Body ( Fig. 7 A) slender, with a typical diaptomid shape. Rostrum represented by pair of soft, finger-like filaments, pointed backward ( Figs. 7 C, D; 11A). Pd4 and Pd5 fused, with rounded posterolateral margins, without sensilla/spines ( Figs. 7 A; 11B). Pd5 asymmetrical, with slightly larger left wing; posterolateral margins rounded, with no dorsal ornamentation; sensilla lack on both sides ( Figs. 7 A; 11B).

Urosome of 3 free somites (ratio of Ur1: Ur2: Ur3: CR = 0.48: 0.12: 0.19: 0.21). Ur1 (genital double-somite) ( Figs. 7 A, E; 11B) about 1.8 times as long as wide, slightly asymmetrical in dorsal view; right proximal margin slightly swollen on proximal part; without lateral sensilla. Genital field with pair of gonopores, divided by median longitudinal septum; gonopores covered by large genital operculum; genital area large ( Fig. 7 E); spermatophore inserted on posterolateral margin of genital field. Ur2 small, cylindrical, about 0.7 times as long as wide. Ur3 (anal segment) as long as wide and as long as caudal rami; deep cleft posteriorly, lateral margins almost straight. Anal operculum small, semicircular, posterior margin smooth.

Caudal rami ( Figs. 7 A, E) symmetrical, 1.8–2.1 times as long as wide (mean 1.9, N=10). Inner and outer margins smooth; with 5 plumose setae (setae II–VI) and smooth, articulated dorsal seta (VII), inserted on inner distal corner; seta I lack. Seta II shortest, other similar in length. Seta VII 1.3 times as long as setae III–VI.

Antennule 25-segmented ( Fig. 8 A), reaching beyond posterior margins of caudal rami. Details of armament the same as in N. phongnhaensis , including position of the longest setae.

Antenna, mandible, maxillule, maxilla and maxilliped ( Figs. 8 B, C–D, E, F, G, respectively) similar to N. phongnhaensis . P1–P4 ( Figs. 7 F–I) armature the same as in N. phongnhaensis .

P5 ( Figs. 10 G; 11I, K). Coxa cylindrical, about 1.3 times as long as wide, posterior surface with small protuberance bearing short spiniform structure at 3/4 of segment length. Bases triangular, asymmetrical; left one larger than right one; without seta on lateral margins. Left Endp very small, triangular, with rounded tip, no armature; right Endp lack. Exp 2-segmented on both sides; Exp-1 cylindrical, elongated, about 2.2 times as long as wide; Exp-2 short, prolonged into terminal claw-like apophysis, with row of tiny spinules on both margins, lateral spine lack.

Description of male. Total length (without caudal setae) 605–655 µm, mean 629 µm (N= 25). Mean prosome length: 463 µm; mean urosome length: 193 µm; prosome/urosome ratio 2.4 (N= 10). Preserved specimens colourless and eyeless. Body slender, with typical diaptomid shape ( Fig. 9 A). Rostral field as in female.

Pd4 and Pd5 fused, with suture limited to lateral margins only. Pd5 slightly asymmetrical, with rounded posterior margins, right lobe larger; without sensilla ( Figs. 9 C, 11C).

Urosome of 5 free somites, simmilar to N. phongnhaensis with urosomites ratio 1–5 + CR as follows: 0.16: 0.13: 0.13: 0.15: 0.21: 0.22. Caudal rami symmetrical, 1.8–1.9 times as long as wide (mean 1.8, N= 10). Inner and outer margins smooth; setae II–VI plumose; dorsal seta (VII) articulated, smooth, inserted on inner distal corner of caudal ramus. Seta II shortest, about 0.8 as long as seta VI; dorsal seta (VII) 1.4 times as long as seta VI.

Antennulae ( Figs. 9 D, E) relatively shorter than in female, reaching middle of caudal rami. Armature of antennules as in N. phongnhaensis .

Structure and armature of antennae, mouthparts and P1–P4 as in female.

P5 asymmetrical, coxae each with 1 spine at 3/4 of segment length, right one larger. Right P5 ( Figs. 10 A, B, F; 11D, E) basis sub-rectangular, about 1.2 times as long as wide; with large, triangular hyaline lobe with broadly rounded tip on distal inner corner; no seta on lateral margin. Exp-1 trapezoidal, as long as wide, distal outer corner with small rounded process. Exp-2 elongate, slightly curved inward, about 2.2 times as long as wide; outer lateral spine slightly curved, inserted at distal 3/4 of segment length, extending well beyond distal margin of Exp-2. Exp-2 claw sickle-like, slender, about 1.8 times as long as Exp-2; inner margin with row of tiny spines. Endp lack.

Left P5 ( Figs. 10 C–E; 11D–H) long, reaching middle part of right Exp-2. Basis about 1.3 times as long as wide; outer margin straight, without lateral seta; inner margin slightly convex. Exp-1 1.9 times as long as wide, curved, with row of short setules on inner margin. Exp-2 short, rectangular, about 0.7 times as long as wide; inner margin with field of short setules; apical process digitiform, elongated, as long as segment bearing it, with small serrated membrane on inner margin and tip divided with two small chitinous processes. Subterminal seta stout, spiniform, 2 times as long as apical process; proximal part 2 short serrated membrane on inner margin. Endp 1- segmented, short, triangular, 1.4 times as long as wide; tip with group of short setules.

Etymology. The new species is named after Assoc. Prof. Ho Thanh Hai from the Institute of Ecology and Biological Resources (IEBR), in recognition of his contribution to the knowledge of Vietnamese copepods.

Figures

FIGURE 7. Nannodiaptomus haii sp. nov. Female: A, habitus, dorsal view; B, setulation of terminal caudal setae; C, rostrum, frontal view; D, rostrum, ventral view; E, urosome, ventral view; F, leg 1; G, leg 2; H, leg 3; I, leg 4. Scale bars: 100 µm.

FIGURE 8. Nannodiaptomus haii sp. nov. Female: A, antennula; B, antenna; C, mandible; D, mandible, gnathal lobe; E, maxillula; F, maxilla; G, maxilliped. Scale bars: A – C, E – G, 100 µm; D, 10 µm.

FIGURE 9. Nannodiaptomus haii sp. nov. Male: A, habitus, dorsal view; B, setulation of terminal caudal setae; C, pedigerous somites 4 and 5, genital somite and urosomite 2, dorsal view; D, right antennule, evident segments 1 – 13; E, right antennule, evident segments 14 – 22. Scale bars: 100 µm.

FIGURE 10. Nannodiaptomus haii sp. nov. Male: A, leg 5, posterior view; B, right leg 5, lateral view; C, left leg 5, lateral view; D, left leg 5, posterior view; E, left leg 5, distal part, anterior view; F, right leg 5, detail of basis and Exp- 1, anterior view. Female: G, leg 5, posterior view. Scale bars: A – C, 100 µm; D – G, 10 µm.

FIGURE 11. Nannodiaptomus haii sp. nov. SEM micrographs. Female: A, rostrum, ventral view; B, pedigerous somite 5 and genital double-somite, dorsal view. Male: C, pedigerous somite 5, genital double-somite, urosomite 2 and 3, dorsal view; D, leg 5, anterior view; E, leg 5, posterior view; F – H, left leg 5 Exp- 2. Female: I, leg 5, anterior view; K, leg 5, posterior view.