Taxonomical, ecological and zoogeographical studies on anisitsiellid water mites (Acari: Hydrachnidia: Anisitsiellidae Koenike, 1910) from Madagascar Author Goldschmidt, Tom text Zootaxa 2008 2008-12-05 1954 1 1 120 https://biotaxa.org/Zootaxa/article/view/zootaxa.1954.1.1 journal article 10.11646/zootaxa.1954.1.1 1175­5334 5240917 Mamersella thienemanni K. Viets, 1929 ( Figs 123 –159, Table 7 , 8 ) Material examined: MD 33 , Madiorano ( Fianarantsoa ), spring at right border of stream crossing the railroad at km 51.2 ( MD 31 ), 650 m asl , 17.0 °C, 53 µS/cm, 18.08.2001 , 1/1/0 mounted, 1/2/0 unmounted ; MD 36 , Andrambovato ( Fianarantsoa ), spring brook 0.5 km south-east from the 1.07 km-railway-tunnel, 900 m asl , 16.1 °C, 35 µS/cm, 19.08.2001 , 0/1/0 mounted, 0/1/0 unmounted ; MD 45 , Andrambovato ( Fianarantsoa ), riparian spring at stream east railway-tunnel 4 (about 1 km west of the village), 800 m asl , 16.5 °C, 47 µS/cm, 22.08.2001 , 2/1/0 mounted, 2/0/0 unmounted ; MD 63 a, Andohahela ( Tulear ), Isaka , stream exposition west 1 km north from the village, riffle, 250 m asl , 19.7 °C, 136 µS/cm, 07.09.2001 , 2/2/0 mounted, 2/3/0 unmounted ; MD 68 , Andohahela ( Tulear ), Fenoevo , first spring north pass RIP 118, 700 m asl , 08.09.2001 , 1/ 1/1 mounted, 1/1/1 unmounted ; MD 71 b, Andohahela ( Tulear ), Isaka , spring area south pass RIP 118 (km 36), spring brook, 700 m asl , 16.0–18.4 °C, 55–60 µS/cm, 10.09.2001 , 1/2/0 mounted, 1/0/0 unmounted ; MD 109 , Ankaratra (Antananarivo), Reserve Manjakatompo , riparian spring exposition south-east at spring brook north deviation to Analamitana ( MD 108 ), 1850 m asl , 14.3 °C, 3 µS/cm, 08.10.2001 , 1/2/1 mounted, 2/2/0 unmounted ; MD 137 , Marofototra ( Antalaha , Antsiranana ), rheocrene exposition south, north Antanambazaha , 100 m asl , 24.2 °C, 8 µS/cm, 05.11.2001 , 1/1/0 mounted, 1/2/0 unmounted ; MD 139 , Marofinaritra ( Antalaha , Antsiranana ), spring north the path about 1 km south-west Marofototra , 70 m asl , 24.0 °C, 14 µS/ cm, 05.11.2001 , 0/1/0 mounted, 0/1/0 unmounted ; MD 141 , Andranomifototra ( Andapa , Antsiranana ), Tanambao , rheocrene near km 27 Route Nationale 3b, 140 m asl , 22.9 °C, 6 µS/cm, 09.11.2001 , 4/3/0 mounted, 5/ 4/0 unmounted ; MD 143 , Andapa ( Antsiranana ), riparian springs at Rivière Masiaposa (crossing Route Nationale 3b at km 5–6), 700 m asl , 20.8 °C, 10 µS/cm, 10.11.2001 , 4/2/0 mounted, 2/4/0 unmounted ; MD 148 , Andapa ( Antsiranana ), rheocrene near km 1 of Route Nationale 3b to Sambava , 600 m asl , 20.8 °C, 14 µS/cm, 11.11.2001 , 2/3/1 mounted, 0/6/4 unmounted ; MD 154 , Joffreville ( Montagne d’Ambre , Antsiranana ), Rivière de Manques in Reserve Fontenay , 550 m asl , 21.9 °C, 25 µS/cm, 17.11.2001 , 2/0/1 mounted, 0/1/0 unmounted ; MD 156 , Joffreville ( Montagne d’Ambre , Antsiranana ), rheocrene at right tributary Rivière de Manques in Reserve Fontenay , 610 m asl , 21.2 °C, 25 µS/cm, 18.11.2001 , 1/1/1 mounted, 1/1/2 unmounted ; MD 157 , Joffreville ( Montagne d’Ambre , Antsiranana ), riparian springs at right tributary Rivière de Manques in Reserve Fontenay , 650 m asl , 21.5 °C, 28 µS/cm, 18.11.2001 , 7/12/2 mounted, 35/19/7 unmounted ; MD 160 , Joffreville ( Montagne d’Ambre , Antsiranana ), riparian springs at right border of Rivière Antomboka downstream sacred cascade, 1000 m asl , 18.0 °C, 20 µS/cm, 19.11.2001 , 5/6/0 mounted, 12/10/0 unmounted ; MD 161 , Joffreville ( Montagne d’Ambre , Antsiranana ), riparian springs at Rivière de Manques in Reserve Fontenay , 730 m asl , 20.9 °C, 11 µS/cm, 20.11.2001 , 4/12/2 mounted, 26/15/3 unmounted ; MD 162 , Joffreville ( Montagne d’Ambre , Antsiranana ), Rivière de Manques in Reserve Fontenay , 730 m asl , 21.5 °C, 15 µS/ cm, 20.11.2001 , 0/1/0 mounted ; MD 164 , Joffreville ( Montagne d’Ambre , Antsiranana ), riparian springs at Rivière de Manques in Reserve Fontenay , 580 m asl , 21.0 °C, 31 µS/cm, 20.11.2001 , 3/8/2 mounted, 3/6/0 unmounted ; MD 166 , Joffreville ( Montagne d’Ambre , Antsiranana ), spring brook at right border of Rivière Antomboka downstream large cascade, 850 m asl , 20.4 °C, 24 µS/cm, 21.11.2001 , 1/2/0 mounted, 0/1/0 unmounted ; MD 167 , Joffreville ( Montagne d’Ambre , Antsiranana ), riparian rheocrenes at Rivière Antomboka downstream large cascade, 850 m asl , 20.8 °C, 24 µS/cm, 21.11.2001 , 7/9/1 mounted, 13/18/0 unmounted . Habitat: Mainly springs (some streams and spring brooks) at 70–1850 (mainly 500–1000) m asl. Distribution: Indonesia , India , Madagascar (mainly northern mountain ranges and Montagne d’Ambre, also Eastern slope, Central and southern mountain ranges). Diagnosis (Malagasy specimens): Idiosoma rounded-oval; large dorsal plate bears post-ocular setae, Dgl- 3 to -5 (in some specimens also Dgl-6) and Lgl-4; soft, lined integument beside dorsal plate bears Dgl-2, Lgl- 1 to -3, Vgl-2 to -4 (in some specimens also Dgl-6), three pairs of small platelets and five pairs of lyrifissures; ventral shield antero-dorsally (mostly) surpassing anterior coxae; Cx-I fused medially; caudal margin of Cx- IV surpassing genital field; excretory pore clearly on ventral shield; genital field elongated oval in male, more compact rectangular-oval in female, acetabula elongated-oval, touching each other; legs stout, leg-IV with many heavy setae; claws of leg-I to -III simple; capitulum compact, rostrum short; palp relatively compact; chelicera slender. TABLE 7. Measurement data for Mamersella thienemanni K. Viets, 1929 from Madagascar. Measurements given in µm.
Mamersella thienemanni
males (n = 7) females (n = 11) deutonymphs (n = 3)
mean min max sd mean min max sd mean min max sd
Dorsal plate L 578 530 625 30.0 683 546 730 48.7 446 441 473 16.9
Dorsal plate W 378 347 420 23.2 441 373 525 45.1 284 278 326 25.9
Dorsal plate L/W 1.55 1.47 1.61 0.05 1.51 1.30 1.68 0.10 1.56 1.45 1.60 0.08
Ventral shield L 693 641 693 20.9 777 651 845 58.0 551 536 620 44.7
Ventral shield W 562 467 693 73.7 709 567 809 76.2 536 483 578 47.3
Ventral shield L/W 1.23 1.00 1.37 0.13 1.11 0.96 1.34 0.09 1.11 0.95 1.16 0.11
Coxal field tL 457 431 462 10.8 499 431 541 31.4 389 368 410 21.0
Cx-III W 310 263 331 24.2 341 305 383 28.7 278 273 284 5.3
Coxal field tL/Cx-III W 1.47 1.40 1.74 0.11 1.46 1.37 1.60 0.09 1.37 1.35 1.47 0.07
Cx-I mL 105 100 105 2.4 110 90 120 8.1 90 88 95 3.8
Cx-III mL 90 85 100 5.0 90 65 103 11.1 95 95 100 2.9
Cx-I / Cx-III mL 1.17 1.00 1.24 0.08 1.17 1.11 1.57 0.14 0.95 0.92 0.95 0.02
Genital field L 125 120 135 4.9 150 135 170 9.5 88 78 90 6.6
Genital field W 90 80 100 6.6 115 100 128 6.8 113 105 130 12.8
Genital field L/W 1.41 1.30 1.56 0.09 1.34 1.23 1.39 0.05 0.69 0.69 0.83 0.08
Egg, diameter 118 105 145 10.6
Capitulum vL 173 165 190 8.9 200 178 215 9.4 150 145 155 5.0
Capitulum H 114 103 125 8.6 121 113 145 13.1 105 100 110 5.0
Chelicera L 260 243 265 11.8 305 258 330 22.5 215 215 215
Chelicera bs L 190 178 193 8.0 220 193 250 18.9 155 155 155
Chelicera claw L 70 65 73 3.8 80 65 85 6.4 60 60 60
Chel bs / claw L 2.71 2.66 2.73 0.04 2.96 2.59 3.13 0.24 2.58 2.58 2.58
Chelicera H 48 48 50 1.4 53 50 60 3.7 43 43 43
CheliceraL/H 5.30 5.11 5.47 0.18 5.75 5.16 5.50 0.5 5.06 5.06 5.06
P1 dorsal L 25 23 25 1.3 25 23 30 2.3 20 20 23 1.4
P2 dL 113 108 120 4.9 130 115 148 10.5 95 90 100 5.0
P3 dL 55 50 55 2.1 65 55 70 5.0 48 48 50 1.4
P4 dL 125 118 125 3.3 145 135 165 10.9 110 108 115 3.8
P5 dL 23 20 25 1.6 25 20 30 2.5 20 20 20 0.0
Palp tL 339 323 350 10.9 398 350 433 27.5 295 285 305 10.0
P1 rel L 0.07 0.07 0.08 0.004 0.07 0.06 0.07 0.004 0.07 0.07 0.08 0.01
P2 rel L 0.34 0.33 0.34 0.01 0.33 0.32 0.34 0.01 0.32 0.32 0.33 0.01
P3 rel L 0.16 0.15 0.16 0.004 0.16 0.16 0.18 0.01 0.16 0.16 0.17 0.003
P4 rel L 0.37 0.36 0.37 0.005 0.38 0.36 0.39 0.01 0.38 0.37 0.38 0.002
P5 rel L 0.07 0.06 0.07 0.003 0.06 0.06 0.07 0.01 0.07 0.07 0.07 0.002
P1 H 40 40 45 2.0 45 40 50 3.1 35 35 40 2.9
P2 H 69 60 73 5.4 70 65 80 6.0 50 50 55 2.9
P3 H 41 40 45 2.5 48 43 55 3.5 38 35 40 2.5
......continue TABLE 7. (continued)
Mamersella thienemanni
males (n = 7) females (n = 11) deutonymphs (n = 3)
mean min max sd mean min max sd mean min max sd
P4 H 29 25 30 2.5 30 28 35 2.0 25 25 25
P5 H 16 15 18 1.4 18 18 23 1.7 15 15 15
P1 L/H 0.59 0.56 0.63 0.04 0.58 0.50 0.67 0.06 0.57 0.50 0.64 0.07
P2 L/H 1.70 1.57 1.83 0.10 1.81 1.68 1.93 0.07 1.82 1.80 1.90 0.05
P3 L/H 1.24 1.22 1.38 0.07 1.33 1.27 1.44 0.06 1.27 1.25 1.36 0.06
P4 L/H 4.22 4.17 5.00 0.37 4.71 4.50 5.17 0.21 4.40 4.30 4.60 0.15
P5 L/H 1.46 1.14 1.50 0.15 1.29 1.11 1.71 0.17 1.33 1.33 1.33
II-leg-1 L 58 55 60 2.2 60 50 65 5.5 44 40 48 5.3
H 43 43 45 1.2 50 45 55 4.3 40 40 40
II-leg-2 L 75 70 80 3.7 83 70 95 8.7 60 55 65 5.0
H 40 40 45 2.4 45 40 50 3.9 35 35 38 1.4
II-leg-3 L 75 70 80 3.5 88 75 98 8.4 60 60 65 2.9
H 40 35 40 2.4 45 38 48 4.0 35 33 35 1.4
II-leg-4 L 95 85 95 3.9 103 93 120 10.3 75 73 80 3.8
H 38 35 40 2.2 45 38 45 3.2 30 30 33 1.4
II-leg-5 L 108 100 110 3.7 115 110 135 9.1 95 85 95 5.8
H 35 33 38 1.7 40 35 45 3.7 33 30 33 1.4
II-leg-6 L 133 125 140 5.0 140 130 158 10.4 115 113 118 2.5
H 40 35 43 2.2 45 40 45 2.4 35 30 35 2.9
IV-leg-1 L 120 100 125 9.6 130 5 153 44.7 100 98 105 3.8
H 63 60 65 2.5 66 53 78 7.4 53 45 53 4.3
IV-leg-2 L 90 85 90 2.7 101 93 115 6.2 75 70 75 2.9
H 53 50 53 1.4 55 48 70 6.9 45 35 45 5.8
IV-leg-3 L 95 85 100 6.0 101 95 125 9.7 78 75 80 2.5
H 48 45 50 2.5 51 45 60 5.1 40 40 43 1.4
IV-leg-4 L 125 123 140 7.0 141 138 165 9.8 115 110 120 5.0
H 40 35 40 2.2 45 40 53 4.9 35 35 38 1.4
IV-leg-5 L 145 145 160 7.1 169 160 190 9.5 128 125 135 5.2
H 28 25 30 1.8 30 28 35 2.9 25 25 28 1.4
IV-leg-6 L 145 130 150 8.7 163 153 175 7.3 120 120 140 11.5
H 15 15 18 1.1 18 15 20 2.3 15 15 15
Description, Malagasy males (n = 7): Idiosoma rounded-oval ( Figs 123 , 131 ); heavy sclerotized body parts very pale greyish-purple; dorsum mainly covered by large, irregular oval plate (L/W 530-625/347-420), in a curved row including Dgl-3, -4, -5, Lgl-4 – and at posterior margin of most specimens Dgl-6; post-ocular setae slightly medial between Dgl-3 and -4 ( Figs 124 , 132 ); in lined, soft integument around dorsal plate: Dgl- 2 anterior, Lgl-1 to -3 lateral and Vgl-2 to -4 latero-caudal, furthermore three pairs of small platelets (lateral Dgl-2, lateral dorsal plate between Lgl-4 and Vgl-3 and latero-caudal Dgl-6) and five pairs of lyrifissures (posterior small anterior platelets, posterior Lgl-1, between Lgl-2 and -3, Vgl-3 and -4, Vgl-4 and -2); lateral eyes oval, separated on both sides (often lost in preparation), lying free under integument ( Figs 124 , 132 ); large trapezoid frontal plate bearing Dgl-1 and pre-ocular setae ( Fig. 125 ); venter completely sclerotized, forming unified ventral shield with margins of coxae still visible (L/W 641-693/467-693); Cx-I medially fused in caudal half; medial margins of Cx-III slightly convex, approximate; Cxgl-2 far medial, between Cx-II and Cx-III; Cxgl-4 centrally in medial third of Cx-III ( Figs 123 , 131 ); medial margin of Cx-IV concave, forming very narrow genital bay, caudal margin rounded, caudally extending well beyond genital field, latero-caudally convex curved towards insertions of legs-IV, lateral margin reaching dorso-laterally up to area of Cx-II; Cx-IV anterior to insertion of legs-IV in some specimens with small ridge ( Fig. 131 ); genital field elongated, anteriorly tapering, lateral margins straight, anteriorly and posteriorly smoothly rounded; not reaching caudal margin of Cx-IV; acetabula mid-sized, elongated-oval, touching each other, Ac3 smaller than Ac1 and Ac2, Ac1 and Ac3 slightly distant from anterior and posterior margins of genital flaps ( Figs 123 , 131 ); setae of Vgl- 1 latero-caudal to genital field, close to medio-caudal margin of Cx-IV, within genital bay ( Figs 123 , 131 ); excretory pore incorporated in ventral shield ( Figs 123 , 131 ); genital skeleton relatively slender, brachia distalia slender, oblique, brachia proximalia stronger, distally extend, oblique ( Figs 126 , 133); legs strong, bearing several heavy setae; leg-I to -III with well developed slender claws without clawlets, leg-II in most specimens with several long, thin hair-like setae, leg-I-6 and leg-II-6 distally extend, ventro-distally with many short hair-like setae ( Figs 127 , 134, 135), leg-IV-4 to -6 ventrally with regular rows of strong setae, leg-IV-6 distally tapering (Figs 128, 136, 137); capitulum compact (in some specimens more elongate ( Table 7 )), rostrum very short (Fig. 138); chelicera with slender, sharply pointed claw, basal segment with slight dorsal hump (Figs 130, 139, 140); palps relatively compact, P1 without dorsal setae, P2 with pinnate, ventro-lateral seta, six dorsal setae, P3 with two lateral and two medio-dorsal setae, P4 relatively slender, distally tapering, ventral setae beside small protrusion, P5 relatively compact (Figs 129, 138, 141). FIGURES 123–127. Mamersella thienemanni K. Viets, 1929 , male (MD 143). 128–130. Mamersella thienemanni K. Viets, 1929 , male (MD 161): 123, idiosoma, ventral view; 124, idiosoma, dorsal view; 125, frontal plate; 126, genital skeleton, antero-lateral view (slightly distorted); 127, leg-II; 128, leg-IV; 129, right palp, medial view; 130, chelicera, lateral view. Scale bars = 100 µm. FIGURES 131, 132. Mamersella thienemanni K. Viets, 1929 , male (MD 45). 133. Mamersella thienemanni K. Viets, 1929 , male (MD 154b). 134–137. Mamersella thienemanni K. Viets, 1929 , male (MD 160). 138–141. Mamersella thienemanni K. Viets, 1929 , male (MD 161): 131, idiosoma, ventral view; 132, idiosoma, dorsal view; 133, genital skeleton, anterior view; 134, leg-II, posterior view; 135, leg-II anterior view; 136, leg-IV, posterior view; 137, leg-IV, anterior view; 138, capitulum with left palp, lateral view; 139, chelicera, lateral view; 140, chelicera medial view; 141, right palp, medial view. Scale bars = 100 µm. FIGURES 142, 143. Mamersella thienemanni K. Viets, 1929 , male (SMF 2732). 142, genital skeleton, anterior view; 143, leg-IV (first segment slightly broken). Scale bar = 100 µm. FIGURES 144, 145. Mamersella thienemanni K. Viets, 1929 , female (MD 164). 146. Mamersella thienemanni K. Viets, 1929 , female (MD 109). 147–149 . Mamersella thienemanni K. Viets, 1929 , female (MD 157): 144, idiosoma, ventral view; 145–147, idiosoma, dorsal view; 148, capitulum with left palp and chelicera, lateral view; 149, right palp, medial view. Scale bars = 100 µm. FIGURES 150–153. Mamersella thienemanni K. Viets, 1929 , female (MD 161): 150, idiosoma, ventral view; 151, idiosoma, dorsal view; 152, capitulum with left palp and chelicera, lateral view; 153, right palp, medial view. Scale bars = 100 µm. Female (Malagasy specimens, n = 11): Idiosoma larger than in male ( Figs 144 , 150 ); dorsal plate variable in size (L/W 546–730/373–525), in most specimens Dgl-6 not fused with dorsal plate ( Figs 145 –147, 151); ventral shield in most specimens more rounded (L/W 651–845/567–809); genital field more compact ( Figs 144 , 150 , Table 7 ); legs and gnathosoma similar to males (Figs 148, 149, 152, 153). FIGURES 154–156, 158, 159. Mamersella thienemanni K. Viets, 1929 , deutonymph (MD 156). 157. Mamersella thienemanni K. Viets, 1929 , deutonymph (MD 154d): 154, idiosoma, ventral view; 155, idiosoma, dorsal view; 156, leg-II-2 to -6; 157, leg-IV; 158, capitulum with left palp and chelicera, lateral view; 159, right palp, medial view. Scale bars = 100 µm. TABLE 8. Measurement data for Mamersella thienemanni K. Viets, 1929 from Indonesia (taken from the species description by K. Viets (1929)) and for M. maryellenae Cook, 1967 from India (taken from the species description by Cook (1967)) . Measurements given in µm.
Mamersella thienemanni K. Viets, 1929 maryellenae Cook, 1967
male female males
Dorsal plate L 635 578 623 631
Dorsal plate W 420 412 403 418
Dorsal plate L/W 1.51 1.40 1.55 1.51
Ventral shield L 742 880 653 684
Ventral shield W 750 743 582 597
Ventral shield L/W 0.99 1.18 1.12 1.15
Cx-I mL 120
Cx-III mL 83
Cx-I / Cx-III mL 1.45
Genital field L 144 149 142 156
Genital field W 91 110 100 104
Genital field L/W 1.58 1.35 1.42 1.50
Egg, diameter 117
Capitulum vL (154) (163) (171)
Chelicera L 270 281 288
Chelicera claw L 75
Chelicera H 54
P1 dorsal L 23 24 27
P2 dL 112 121 131
P3 dL 54 60 62
P4 dL 129 124 152
P5 dL 29 26 31
Palp tL 347 355 403
P1 rel L 0.07 0.07 0.07
P2 rel L 0.32 0.34 0.33
P3 rel L 0.16 0.17 0.15
P4 rel L 0.37 0.35 0.38
P5 rel L 0.08 0.07 0.08
P2 H 62
P3 H 46
P4 H 31
IV-leg-4 L 125 148
IV-leg-5 L 145 173
IV-leg-6 L 135 156
Deutonymph (n = 3): Idiosoma very similar to adults, rounded-oval (Fig. 154); large dorsal plate irregular, elongated-oval (L/W 441–473/278–326), bearing Dgl-3 to -5; soft, lined integument around dorsal plate slightly broader than in adults, dorsal plate surrounded by Dgl-2, Lgl-1 to -4 and Dgl-6 (from anterior to caudal), further latero-caudal Vgl-2 to -4, furthermore five pairs of lyrifissures; two pairs of lateral eyes on each side separated under integument (Fig. 155); ventral shield complete, rounded (L/W 536-620/483-578); coxal field very similar to adults; provisional genital field as in adults closely fit in genital bay between Cx-IV, two pairs of acetabula, laterally with three pairs of setae and central bifurcate sclerite (Fig. 154, Table 7 ); setae of Vgl-1 posterior caudal margin of Cx-IV; excretory pore on ventral shield, close to caudal margin; legs and gnathosoma similar to adults, however bearing less setae (Figs 156, 157); capitulum compact (Fig. 158), P2 with three dorsal setae, without ventral seta, P4 slender, with ventral setae in distal half on small protrusions (Figs 158, 159).
Remarks: Mamersella thienemanni K. Viets, 1929 is widespread in Southern Asia; originally the species has been collected in springs, a river and a seepage area in Java, Sumatra and Bali, respectively (K. Viets 1935 ), and has been found again on Java ( Lundblad 1971 ) and in a well in India ( Panesar 2004 ). In Madagascar it is by far the most abundant anisitsiellid species, representing 71 % of all specimens in this study. The species was found in all regions of Madagascar , especially in springs where it is the most common and abundant species. The investigation of extensive material from springs and streams in various parts of Madagascar showed a great variability in the degree of fusion of the dorsal glandularia and small platelets with the main dorsal plate (the fusion of Dgl-6 is mainly subject to sexual dimorphism (fused mostly in males), beside this there are individual differences in the size of the main dorsal plate (reaching close to the Lgl-1 to - 4 in some specimens, even including Lgl-3 on one side in one specimen (Fig. 147), therefore also the number of small platelets surrounding the main dorsal plate is variable; generally the outline of the dorsal plate is irregular (see especially Figs 145 –147)). Furthermore the length of the gnathosoma is remarkably variable (vL 165–190 in males, 178–215 in females). The type specimen of M. thienemanni (SMF, Viets-Collection, slide number 2732) differs only very slightly from the Malagasy specimens in a slightly slenderer genital skeleton ( Fig. 142 ) and leg-IV-2 ventrodistally bearing two large setae instead of one ( Fig. 143 ). Nevertheless it seems reasonable to assign the Malagasy specimens to M. thienemanni . A second species of the genus — M. maryellenae Cook, 1967 — was described from a cataract and a small river in India ( Cook 1967 ). The differentiation of M . maryellenae from M . thienemanni had been based upon the following characters: Genital field larger, reaching caudal margin of Cx-IV (in M . thienemanni caudal margin of Cx-IV is extended further posterior); excretory pore in an indentation of the ventral shield (fused with the ventral shield in M . thienemanni ); fusion of Dgl-6 with caudal margin of dorsal plate (glandularia not fused, lying directly posterior dorsal plate in M . thienemanni ). These character states are present in the Malagasy specimens in great variation and therefore have to be excluded from the differential diagnosis of M . maryellenae . Mamersella thienemanni seems to be a very widespread and variable species. A deutonymph originally described as M. thienemanni by K. Viets (1935) might rather be regarded as the deutonymph of Bandakia orientalis K. Viets, 1935 . The latter species was found in the same sample and the described specimen shows the characteristic provisional genital field of the deutonymph of Bandakia ( Panesar 2004 ) . The deutonymph of M. thienemanni collected in Madagascar now — is described above and shows character states that fit well with Mamersella thienemanni .