A Review of the Genus Thermocyclops - Zoological Studies

Chaicharoen et al. – Review of Thermocyclops in Cambodia 789S2 caudal setae are presumably an environmentdependentcharacter, which vary from straight tipsin the littoral population (Cambodia) to stronglycurved tips in a pelagic habitat (Lake Lanao).More data are needed on the morphometrics,and S2 and P4 coupler morphology in both thelittoral and pelagic populations in Lake Lanao andCambodia to answer the following questions: Dothe littoral populations of T. wolterecki in LakeLanao have the same morphology as the smallwater-bodypopulations in Cambodia?; and Doforms with intermediate morphologies exist?Fig. 8. Position of the syntypes of Thermocyclops woltereckion slide SMNK 4105. The lectotype designated herein ismarked with an arrow.Thermocyclops maheensis (Lindberg, 1941)(Figs. 9-12)Mesocyclops (Thermocyclops) maheensis Lindberg 1941: 259-265, fig. 1, table 1; Herbst 1986: 165-180; Thermocyclopsmaheensis Mirabdullayev et al. 2003: 246, fig. 113;Alekseev and Sanoamuang 2006: 277-290, table 2.Material examined: Cambodia: Kratie Prov.,Sambo Dist., Kbal Damrey, pond, 12°50'N,106°10'E, 14 Feb. 2007, 1 , slide CB20(1A,B);Kratie Prov., pond, 12°51'N, 106°11'E, 14 Feb.2007, 1 , slide CB21(1A,B); Stung Treng Prov.,irrigation canal, 13°31'N, 105°59'E, 15 June2007, 1 , slide CB31(1A,B); Stung Treng Prov.,temporary pond, 13°19'N, 106°06'E, 12 June2007, 1 slide CB45(1A,B); Stung Treng Prov.,pond, 13°16'N, 106°06'E, 12 June 2007, 1 , slideCB46(1A,B).Diagnosis: Female (Cambodia). Pediger5 without lateral hairs or spinules (Fig. 9A).Seminal receptacle cruciform, lateral arms curvedposteriorly. Caudal rami (Fig. 9B) with pits onventral surface, no medial hairs. No spinules atimplantation of lateral seta or S4. Tip of S2 varyingfrom straight to strongly curved ventrally.Antennule (Fig. 10A-C) 17-segmented,reaching posterior margin of pediger 4. Hyalinemembrane on last segment extending beyondinsertion of medial seta of segment, withoutnotch. Antennal (Fig. 11B) enp2 with 7 setae.Table 2. Morphometric data on Thermocyclops wolterecki in Lake Lanao (Mindanao, the Philippines,SMNK) and Cambodia (CB 55). C, Cambodia; CR, length of caudal ramus; m/l, medial spine/lateral spine ofP4 endopodite 3; P, Philippines; P4 enp3, P4 endopodite 3 length/width; S1, length of medialmost terminalcaudal seta; S2, length of inner median terminal caudal seta; S3, length of outer median terminal caudalseta; S4, length of lateralmost terminal caudal seta; S5, length of dorsal caudal seta; S6: length of lateralcaudal seta; SE, standard error; M, mean; SD, standard deviationNo S1 (µm) S2 (µm) S3 (µm) S4 (µm) S5 (µm) S6 (µm) S1/CR S1/S4 S1/S5 P4 enp3 m/lC P C P C P C P C P C P C P C P C P C P C P1 105 87 162 207 150 150 45 37.5 40 63 20 24 2.6 2.2 2.33 2.33 2.63 1.39 3.12 3.58 2.00 2.052 100 87 160 200 138 140 45 37.5 44 61 20 26 2.5 2.3 2.22 2.33 2.27 1.43 3.33 2.98 1.95 1.893 110 87 175 222 150 148 45 37.5 40 60 22 25 2.6 2.4 2.44 2.33 2.75 1.46 3.2 3.50 1.90 1.944 100 87 172 220 150 143 45 37.5 40 60 20 24 2.5 2.5 2.22 2.33 2.5 1.46 3.33 3.08 2.00 2.05 103 95 170 222 150 150 48 36 40 65 22 28 2.4 2.5 2.14 2.64 2.56 1.46 3.18 3.41 1.90 2.16 105 - 172.5 - 150 - 42.5 - 39 - 20 - 2.39 - 2.47 - 2.69 - 3.42 - 1.95 -7 100 - 175 - 153 - 42.5 - 40 - 20 - 2.50 - 2.35 - 2.5 - 3.42 - 2.00 -8 100 - 162.5 - 143 - 47.5 - 40 - 20 - 2.50 - 2.11 - 2.5 - 3.5 - 1.90 -9 103 - 162.5 - 133 - 45 - 43 - 22.5 - 2.56 - 2.28 - 2.38 - 3.42 - 1.90 -10 100 - 150 - 138 - 47.5 - 40 - 20 - 2.38 - 2.11 - 2.5 - 3.2 - 2.10 -SE 1.05 1.5 2.56 4.58 2.25 2.04 0.61 0.3 0.5 0.97 0.38 0.7 0.03 0.05 0.03 0.06 0.04 0.01 0.04 0.12 0.02 0.04SD 3.33 3.3 8.1 10.2 7.12 4.54 1.92 0.7 1.5 2.17 1.21 1.6 0.08 0.12 0.13 0.14 0.14 0.03 0.13 0.27 0.07 0.09M 103 89 166.3 214.5 145 146 45.3 37 40 61.8 20.8 25.4 2.50 2.38 2.27 2.39 2.53 1.44 3.31 3.31 1.96 2.00