Parategastes pholpunthini, Saetang, Thanida & Maiphae, Supiyanit, 2015

Saetang, Thanida & Maiphae, Supiyanit, 2015, A new species of Parategastes Sars, 1904 from the Thale Noi Lake, southern Thailand (Copepoda, Harpacticoida, Tegastidae), Zoosystematics and Evolution 91 (2), pp. 167-176 : 167-169

Taxon classification Animalia Harpacticoida Tegastidae

Parategastes pholpunthini sp. n.

Type material.

Holotype: adult female, dissected and mounted on 4 slides, (PSUZC-PK2001-01-PSUZC-PK2001-04); Paratype 1: undissected female, mounted on 1 slide, (PSUZC-PK2001-05); Paratype 2: undissected adult male, mounted on 1 slide, (PSUZC-PK2001-06); Paratype 3: adult female, dissected on 4 slides, (PSUZC-PK2001-07-PSUZC-PK2001-10); Paratype 4: adult male, dissected on 4 slides, (PSUZC-PK2001-11-PSUZC-PK2001-14). All specimens were collected from the type locality on 23 October 2013.

Additional materials.

8 females and 8 males from the type locality are stored in 70% ethanol.

Type locality.

Klong Ban Klang canal, Thale Noi Lake, Phatthalung province, southern Thailand (07°46 ’30.47” N, 100°9 ’31.68” E). The canal is connected to Songkhla Lake. Water temperature ranged between 28.3 to 28.5 °C, pH of 5.71-6.07, salinity 1.1 ppt, depths between 0.8 m to 1.35 m, transparency of 0.2-1.35 m, and dissolved oxygen levels of 3.06-4.24 mgO2/L. This area was covered with aquatic plants, such as Neptunia oleracea Lour., Eichhornia crassipes (C. Mart.) Solms, and Nympheas sp.

Description of the adult female.

Body laterally compressed with sensilla, surface of whole body pitted (Fig. 1A). Total length, measured from the anterior margin of the cephalic shield to the posterior margin of the caudal rami, 280-340 µm (mean = 310 µm, n = 11). Prosome comprising of cephalothorax and three somites bearing P2 to P4. Urosome 5-segmented (Fig. 1D), first urosomite with P5, genital double somite and three abdominal somites. Caudal rami (Fig. 1C) as wide as long, with seven setae of different lengths. All setae smooth.

Egg sac (Fig. 2G) round, containing four eggs, located ventrally between fifth pair of legs.

Rostrum (Fig. 1B) a rounded prominence.

Antennule (Fig. 2A) 6-segmented, aesthetasc on 4th and 6th segments. Armature formula 1-[1], 2-[8], 3-[8], 4-[3+aesthetasc], 5-[5], 6-[10+acrothek]. Aesthetasc on 4th segment fused basally to one smooth seta. Apical acrothek consists of an aesthetasc fused basally with two slender smooth setae. Only seta on first segment bipinnate, all other setae smooth.

Antenna (Fig. 2B) 4-segmented, comprising coxa, basis and 2-segmented endopod. Coxa and basis without ornamentation, exopod 1-segmented with three setae. Enp-1 with one median seta; enp-2 with eight setae (two laterals and six apical).

Mandible (Fig. 2C) gnathobase with four teeth. Coxa-basis with row of long spinules and with two setae; endopod 1-segment with three setae; exopod represented by one seta.

Maxillule (Fig. 2D) precoxal arthrite bearing seven elements. Coxal endite with one seta. Endopod elongated with a row of spinules, five terminal setae, and two setae at outer margin.

Maxilla (Fig. 2E) syncoxa with transverse row of spinules proximo-laterally and with two endites. Precoxal endite with four setae, one seta elongated; coxal endite with three setae. Allobasis with three setae, middle seta forming a strong claw, and three setae at outer margin representing endopod.

Maxilliped (Fig. 2F) subchelate, 2-segmented, comprising syncoxa and basis. Syncoxa with one pinnate seta at the inner distal corner. Basis with row of spinules, one pad-like process ornamented with short spinules on its surface. Endopod 1-segmented, forming a strong claw with one seta proximally.

P1 (Fig. 3A) coxa with a row of setules along inner margin. Basis with a row of spinules along inner margin, one inner seta, and one outer seta. Both rami with 1-segmented endopod wider than exopod. Endopod with a row of setules along outer margin; with one inner proximal biplumose seta, one inner middle modified spine, one inner distal bipinnate spine, two apical bipinnate spines, and one outer bipinnate spine. Exopod with a row of spinules along inner margin; with two apical bipinnate spines, three outer setae, the middle of which being bare, and the others bipinnate.

P2 and P3 (Figs 3B, 4A) coxa with a set of spinules on pronounced disto-lateral corner. Basis elongated with one small outer seta and row of spinules along medial margin. Rami with 3-segmented endopods and 2-segmented exopods; all segments of endopod with a row of setules along outer margins, all segments of exopod with a row of spinules along outer margin.

P4 (Fig. 4B) coxa with a set of spinules on pronounced disto-lateral corner. Basis elongated with one small outer seta and a row of spinules on the inner and outer margins. Both rami 3-segmented. Enp-1 and enp-2 equal in length but shorter than enp-3; enp-1 and enp-2 with inner setae and with a row of setules along outer margins; enp-3 with two apical pinnate spines, and one outer seta. Exp-1 small, with one outer spine; exp-2 with one inner seta and one outer spine, and with a row of spinules on the inner and outer margins; exp-3 with a row of spinules on the outer margin, with one inner pinnate seta, middle inner seta enlarged, this enlarged seta has a peculiar shape with two long pinnae at the distal third, with the bending, and with three shorter pinnae distal end, two apical setae, one seta plumose, another seta inner margin plumose and outer margin pinnate, and two outer pinnate spines.

Armature formula of P1-P4 as in Table 1.

P5 (Fig. 4C) with baseoendopod and exopod; baseoendopod with three lateral biplumose setae, and one inner seta along proximolateral, apically with one inner bipinnate seta and one outer biplumose spine. Exopod with one apical biplumose seta and two outer bipinnate setae, one small seta basally.

Description of the adult male.

Body laterally compressed (Fig. 5A). Total length, 290-310 µm (mean = 290 µm, n = 10). Spermatophore reservoir produced ventrally in a large, elongated prominence bearing distally asymmetrical genital flaps.

Antennule (Fig. 5B) 8-segmented, aesthetasc on 3rd, 4th and 8th segments. Armature formula 1-[1], 2-[9], 3-[7+aesthetasc], 4-[7+aesthetasc], 5-[1], 6-[2], 7-[1], 8-[10+acrothek]. Aesthetasc on 3rd and 4th segment fused basally to one naked seta. Apical acrothek consists of an aesthetasc fused basally with two slender naked setae. Only seta on first segment bipinnate, all others smooth.

Rostrum, antenna, mandible, maxillule, maxilla, maxilliped, P1-P4 (not shown) as in female.

P5 (Fig. 5C) 2-segmented with baseoendopod and exopod; baseoendopod small with long spinule at lateral margin; exopod elongate with one proximal outer seta, one subterminal outer spine and two apical spines.

Etymology.

This species named after Dr. Pornsilp Pholpunthin, who has studied the freshwater copepods in Southern Thailand since last twenty years.