Mongolodiaptomus phutakaensis, Sanoamuang & Koompoot, 2024

Sanoamuang, Laorsri & Koompoot, Kamonwan, 2024, A description of a new species of Mongolodiaptomus Kiefer, 1937 (Copepoda, Calanoida, Diaptomidae) from Thailand with an up-to-date key to the genus, ZooKeys 1209, pp. 19-42 : 19-42

publication ID	https://doi.org/ 10.3897/zookeys.1209.125838
publication LSID	lsid:zoobank.org:pub:2440735C-827B-4446-9463-757DF90C034A
DOI	https://doi.org/10.5281/zenodo.13242488
persistent identifier	https://treatment.plazi.org/id/9B4A5018-E0E5-45C6-9701-A299D8301A81
taxon LSID	lsid:zoobank.org:act:9B4A5018-E0E5-45C6-9701-A299D8301A81
treatment provided by	ZooKeys by Pensoft
scientific name	Mongolodiaptomus phutakaensis
status	sp. nov.

Treatment

Mongolodiaptomus phutakaensis sp. nov.

Figs 1 View Figure 1 , 2 View Figure 2 , 3 View Figure 3 , 4 View Figure 4 , 5 View Figure 5 , 6 View Figure 6 , 7 View Figure 7 , 8 View Figure 8

Mongolodiaptomus sp. Sanoamuang and Dabseepai (2021): 7, 18, 20.

Type locality.

A natural swamp in Kok Phutaka community forest, Muang Kao Phatthana Subdistrict GoogleMaps , Wiang Kao District, Khon Kaen Province, northeast Thailand (16 ° 38 ' 43.77 " N, 102 ° 18 ' 11.90 " E); elevation 220 m a. s. l., water temperature 31.2 ° C, pH 8.2, conductivity 299 µS cm - 1.

Type material.

Holotype: adult male ( THNHM -1V-19371 ), dissected and mounted in glycerol on one slide GoogleMaps . Allotype: adult female ( THNHM -1V-19372 ), dissected and mounted in glycerol on one slide GoogleMaps . Paratypes: three adult males and three adult females ( THNHM -1V-19373 ), undissected and preserved in 4 % formalin GoogleMaps ; collected from the type locality on the same date as the holotype. All specimens were collected on 16 August 2007, by P. Dabseepai and K. Koompoot.

Description of adult male.

Total body length, measured from anterior margin of rostrum to posterior margin of caudal rami, 1.3–1.4 mm (mean = 1.37 mm, n = 10), (Figs 1 A View Figure 1 , 2 A View Figure 2 ). Body smaller and slender than in female. Prosome ~ 2.2 × as long as urosome (Fig. 2 A View Figure 2 ). Rostrum (Fig. 1 B View Figure 1 ) well developed, with two spiniform processes. Pedigers 4 and 5 fused except at lateral margins. Lateral wings of Pdg 5 asymmetrical; right postero-lateral wing shorter than left one; each wing with one thin postero-lateral spine (Fig. 2 A View Figure 2 ).

Urosome (Figs 1 D View Figure 1 , 2 A – C View Figure 2 ) with five somites. Genital somite dilated postero-laterally on right side, shorter than wide, with a curved spine on the right posterolateral corner. Urosomites 2–4 approximately as long as wide each. Urosomites 2–3 (Figs 1 D View Figure 1 , 2 B, C View Figure 2 ) with a patch of hairs on right ventral side. Urosomite 4 with expanded right dorso-posterior margin. Anal somite asymmetrical, right side slightly longer than left side (Fig. 2 A, C View Figure 2 ). Caudal rami asymmetrical (Figs 1 E View Figure 1 , 2 A – C View Figure 2 ), each ramus ~ 2.3 × as long as wide, inner right margin hairy (Figs 1 E View Figure 1 , 2 B View Figure 2 ). Right ramus armed with four chitinous structures on ventral surface; two sharp tips situated proximally and two semicircular knobs distally (Figs 1 E View Figure 1 , 2 B View Figure 2 ). Each ramus with six setae (setae II – VII): setae II – VI plumose, anterolateral (II) seta with smooth region on outer margin proximally; terminal setae (setae IV and V) without fracture plane; dorsal seta (VII) articulated, bare, longest.

Antennule: asymmetrical, extending beyond the end of caudal setae. Left antennule (Fig. 3 F View Figure 3 ): 25 - segmented. Armature formula as in Table 1 View Table 1 . Right antennule (Figs 1 C View Figure 1 , 2 D – F View Figure 2 ) 22 - segmented. Armature formula as in Table 2 View Table 2 . External extension on antepenultimate segment (segment XX) short, comb-like, with five or six teeth (Figs 1 C View Figure 1 , 2 F View Figure 2 ).

Antenna (Fig. 3 A View Figure 3 ): coxa and basis with one and two bare setae on inner distal corner, respectively. Enp two-segmented; Enp - 1 with two setae along inner margin; Enp - 2 with nine setae along inner margin, seven setae apically; all setae bare. Exp seven-segmented: Exp - 1–6 with 1, 3, 1, 1, 1, 1 setae along inner margin; Exp - 7 with one seta on inner margin and three setae apically; all setae bare.

Mandible (Fig. 3 B View Figure 3 ): ~ 6 cuspidate teeth dorsally and one seta on coxal gnathobase dorsally. Basis with four bare setae: one proximally and three distally along inner margin. Enp - 1 with four setae on inner distal corner. Enp - 2 with nine setae apically; two oblique rows of spinules along outer margin. Exp - 1–3 each with one seta on inner margin; Exp - 4 with three setae apically; all setae bare.

Maxillule (Fig. 3 C View Figure 3 ): praecoxal arthrite with nine strong setae laterally and four slender submarginal setae. Coxal endite with four setae; coxal epipodite with nine setae; two proximal-most setae smaller than others. Two basal endites fused to segment bearing them: proximal and distal endite, each with four setae apically; basal exopodite with one short seta. Enp - 1 and Enp - 2 each with four setae apically, proximal segment fused to basis. Exp with six bare setae apically.

Maxilla (Fig. 3 D View Figure 3 ): praecoxa fused to coxa. Proximal and distal endites on praecoxa with three setae apically each. Two coxal endites with three setae apically each. Allobasis with three setae apically. Enp two-segmented; with three setae each.

Maxilliped (Fig. 3 E View Figure 3 ): four medial lobes on syncoxa: setal formula 1, 2, 3, 4, respectively; subdistal inner margin produced into a spherical lobe with a patch of tiny spinules. Basis with three setae along medial inner margin, with a row of tiny spinules proximately. Enp six-segmented, with 2, 3, 2, 2, 2, and 4 bare setae, respectively.

P 1 – P 4 (Fig. 4 A – D View Figure 4 ): coxa with a pinnate seta at innermost distal corner. P 1 and P 2 basis without setae; a reduced bare seta on outer distal margin of P 3 and P 4. Exp longer than Enp; two-segmented Enp and three-segmented Exp on P 1, three-segmented Enp and Exp on P 2 – P 4. Armature formula of P 1 – P 4 as in Table 3 View Table 3 .

P 5 (Figs 1 F – K View Figure 1 , 5 A, B View Figure 5 ): intercoxal sclerite trapezoidal, inner distal margin not produced, without any projection. Right P 5: coxa with an acute, robust spine on extension on posterior surface, its tip bent inward (Figs 1 F View Figure 1 , 5 A View Figure 5 ), inner distal margin slightly produced into a rounded lobe. Basis rectangular, ~ 1.5 × as long as wide; with prominent irregular-shaped chitinous process at mid-distal length on posterior surface (Figs 1 F View Figure 1 , 5 A View Figure 5 ); a small seta on distal outer margin; without any hyaline structure. Enp one-segmented, gradually tapering to distal end, tipped with tiny spinules distally; reaching beyond 1 / 3 of Exp - 2. Exp - 1 shorter than wide, with two chitinous knobs at distal inner corner; outer distal margin produced into acute tip (Figs 1 I View Figure 1 , 5 A, B View Figure 5 ). Exp - 2 slightly incurved, inner margin convex, outer margin concave, ~ 2.5 × as long as wide, with two small processes proximally and distally; principal lateral spine inserted slightly posterior to mid-length of outer margin. Principal lateral spine (Figs 1 K View Figure 1 , 5 A, B View Figure 5 ) somewhat slightly curved, robust, ~ 1 / 2 length of segment. Accessory lateral spine (Figs 1 K View Figure 1 , 5 A, B View Figure 5 ) minute, distal spine situated close to insertion of end-claw (Figs 1 I View Figure 1 , 5 B View Figure 5 ), distal accessory spine smaller than proximal one. End-claw sickle-shaped, long, and slender, with a serrate inner margin, with blunt tip; ~ 1.5 × as long as Exp - 2.

Left P 5 (Figs 1 G – J View Figure 1 , 5 A, B View Figure 5 ): coxa with long bare seta on posterior lobe near distal inner corner; longer and slender than spine on right coxal segment. Basis with long narrow hyaline lamella along inner margin (Figs 1 J View Figure 1 , 5 A, B View Figure 5 ); slender, long posterolateral seta on posterior surface, reaching to middle of Exp - 2 segment (Figs 1 H View Figure 1 , 5 A, B View Figure 5 ). Exp - 1 trapezoidal, tapering towards distal end, medial margin concave with a field of setules (Figs 1 H View Figure 1 , 5 A, B View Figure 5 ). Exp - 2 smaller than Exp - 1, with inner robust seta, longer than Exp - 2; with inner strongly serrate margin (Figs 1 H View Figure 1 , 5 A, B View Figure 5 ). Exp - 3 reduced to thumb-like segment. Enp one-segmented, shorter than Exp - 1, with spinulated tip.

Description of adult female.

Total body length, measured from anterior margin of rostrum to posterior margin of caudal rami, 1.5–1.7 mm (mean = 1.6 mm, n = 10) (Figs 6 A View Figure 6 , 8 A View Figure 8 ). Prosome: urosome ratio ~ 2.4: 1. Prosome similar to that of male. Rostrum fused, symmetrical, acutely pointed (Fig. 8 B View Figure 8 ). Fourth and fifth pedigerous somites incompletely fused. Fifth pediger with sub-asymmetrical posterolateral wings (Figs 6 A, C View Figure 6 , 8 C View Figure 8 ); right wing rounded, left wing triangular and longer than right wing. Urosome 3 - segmented, with asymmetrical genital double-somite (Fig. 6 A – C View Figure 6 ). Genital double-somite longer than urosomite 2, anal somite, and caudal rami combined (Figs 6 B, C View Figure 6 , 8 C View Figure 8 ); right proximal region slightly curved with small spine. Left side with large dorsolateral spine on sub-proximal region. A pair of gonopores and copulatory pores located centrally at ~ 1 / 2 length of genital double-somite (Figs 6 B View Figure 6 , 8 H View Figure 8 ). Urosomite 2 symmetrical, shorter than wide. Anal somite symmetrical, as long as length of caudal rami (Figs 6 C View Figure 6 , 8 I View Figure 8 ); anal operculum small with convex free margin. Caudal rami parallel, symmetrical; both rami with hairy inner and outer margins (Figs 6 C View Figure 6 , 8 I View Figure 8 ). All principal caudal setae slightly dilated anteriorly; dorsal seta approximately as long as principal setae.

Antennule symmetrical; left antennule, antenna, mouthparts, and P 1 – P 4 as in male.

P 5 symmetrical (Figs 7 A, B View Figure 7 , 8 D – G View Figure 8 ). Intercoxal sclerite narrow, triangular. Distal outer margin of coxa extended on anterior side into spiniform apophysis reaching distal part of Exp - 1 (Fig. 7 B View Figure 7 ). Basis with thin, bare seta on outer margin, reaching ~ 1 / 4 of Exp - 1 length. Exp three-segmented (Figs 7 A, B View Figure 7 , 8 E, F View Figure 8 ). Exp - 1 sub-rectangular, ~ 2.3 × as long as wide. Exp - 2 triangular, with a row of strong spinules along both margins; with longitudinal grooves (conveyor canals) on posterior view (Figs 7 A View Figure 7 , 8 D View Figure 8 ), small outer spine proximally. Exp - 3 reduced, represented by a small segment on proximal outer margin of Exp - 2, armed with two unequal spiniform setae apically. Enp two-segmented (Fig. 8 G View Figure 8 ), subconical, ~ 2 / 3 as long as Exp - 1; with obliquely truncate and finely spinulose apex.

Etymology.

The specific epithet is derived from Kok Phutaka, reflecting the name of the area in which the type locality is located. The name is an adjective in the nominative singular, gender feminine.

Distribution.

At present, the new species has been found only in the type locality, a natural swamp in Kok Phutaka community forest in Khon Kaen Province, northeast Thailand. It co-exists with other calanoids, Phyllodiaptomus praedictus Ranga Reddy & Dumont, 1994 and Mongolodiaptomus rarus (Ranga Reddy, Dumont, & Sanoamuang, 1998) . The other artificial ponds nearby also contained M. botulifer ( Kiefer, 1974) . Representatives of the new species were observed only once out of approximately 5,000 sampled sites throughout Thailand. Currently, this species is endemic to Thailand. The new species is present in only one locality throughout the year, and ecological parameters varied in a temperature range of 25.0–32.5 ° C (mean = 29.13 ° C), conductivity 74–495 µS cm - 1 (mean = 201.25 µS cm - 1), and pH 5.16–10.03 (mean = 7.66).