Monatractides cf. ventriosus ( K. Viets, 1916 )

Pešić, Vladimir & Smit, Harry, 2014, Torrenticolid water mites (Acari: Hydrachnidia: Torrenticolidae) from Ghana, Zootaxa 3820 (1), pp. 1-80 : 36-42

Monatractides cf. ventriosus ( K. Viets, 1916)

( Figs. 23A–E , 24A–D , 25H–I , 26H–I , 44D , Tab. 3 )

Atractides ventriosus K. Viets 1916: 263 .

New records. Ghana: Unnamed stream between Apepem and Kojo Amu, Atewa Hills, 6º 10.252 N, 0º 36.520 W, alt. 424 m asl., 27.ii.2013, Smit, 0/1/0; Kue River, Kyabobo NP, 8º 31.087 N, 0º 36.049 E, alt. 208 m asl., 25.ii.2013, Smit, 0/1/0; Laboun River, downstream, Kyabobo NP, 8º 19.931 N, 0º 34.476 E, alt. 303 m asl., 24.ii.2013, Smit, 1/ 0/0 (mounted); Laboun River, downstream of falls, Kyabobo NP, 8º 19.836 N, 0º 35.487 E, alt. 342 m asl., 24.ii.2013, Smit, 1/3/0 (1/1/0 mounted); Ankasa River, Ankasa NP, 5º 13.011 N, 2º 39.126 W, alt. 60 m asl., 13.ii.2013, Smit, 0/1/0; Afiaso stream, Kakum NP, 5º 30.087 N, 1º 26.373 W, alt. 114 m asl., 12.ii.2013 0/1/0; Agumatsa River at first bridge, Agumatsa Wildlife Sanctuary, 7º 06.830 N, 0º 35.760 E, alt. 253 m asl., 22.ii.2013, Smit, 0/1/0 (mounted); Unnamed creek upstream Sagyimase, Atewa Hills, 6º 13.966 N, 0º 33.114 W, alt. 671 m asl., 28.ii.2013, Smit, 0/9/0; Ankasa Exporation Base stream, Ankasa NP, 5º 16.413 N, 2º 38.810 W, alt. 81 m asl., 14.ii.2013 Smit, 0/1/0; Nubui River, Agumatsa Wildlife Sanctuary, 7º 06.986 N, 0º 35.548 E, alt. 254 m asl., 22.ii.2013, Smit, 1/3/0; Akaa Falls, 6º 10.516 N, 0º 11.723 W, alt. 180 m asl., 9.iii.2011, Smit, 0/2/0.

Morphology. General features —Idiosoma roundish; shoulder platelets elongated (shoulder/frontal platelets L ratio 1.9–2.1); frontal margin medially with large anterolaterally pointed apodemes ( Fig. 24D ); Cxgl-4 located far anteriorly, near tips of Cx-I; gnathosomal bay moderately deep, V-shaped, three pairs of knob-like protrusions at the lateral margins of gnathosomal bay; suture line of Cx-IV distinct, originating from lateral edge of genital field; posterior line of primary sclerotization close to posterior margin of genital field; excretory pore and Vgl-2 well separated from the line of primary sclerotization, Vgl–2 posterior to excretory pore; gnathosoma with long dorsal apodemes, rostrum truncated ( Fig. 23D ); distal margin of P-3 and P-4 medially with several pointed extensions; P- 4 with two ventral setae, one very long and away from distal edge ( Figs. 23C , 24C ). Male: medial margin of Cx-II/ III relatively short; genital field subrectangular; ejaculatory complex ( Figs. 23E , 44D ) with large proximal chamber, carina anterior short. Female: genital field pentagonal, anteriorly enlarged, laterally straight, tapering posteriorly.

Remarks. Since the original description of Monatractides ventriosus based on a single female from Cameroon ( K. Viets, 1916), water mites from different regions of Africa have been assigned to this species. As stated by Cook (1966), Goldschmidt & Smit (2009) and Smit et al. (2010), the variability of populations from different regions of the whole distribution area needs to be examined to clarify the taxonomy. The first step in that should be to collect additional material as well as finding a male from the locus typicus of M. ventriosus .

Laboun River, ♂ Laboun falls, ♂ Laboun falls, ♀ Agumatsa River, ♀ In comparison with specimens from Liberia described by Cook (1966), specimens in our study are notably smaller, but do not differ in proportions and general idiosoma and palp morphology. On the other hand, comparison with figures from the original description of K. Viets (1916) suggests that specimens in our study cannot be conspecific with M. ventriosus . The ventral setae on P- 4 in the type specimen are short, not reaching the tip of P-5. In our specimens, and in specimens from Liberia (see Cook 1966), one of P-4 ventral setae is characteristically very long and away from the distal edge. As already observed by Cook (1966) the palps in specimens from Liberia are more like those illustrated by Lundblad (1952) for M. ventriosus from Kenya. However, the specimens from our study differ from specimens from Kenya assigned by Lundblad (1952) to M. ventriosus , in the shape of the ejaculatory complex with a large proximal chamber (vs. small proximal chamber in specimens from Kenya, see Lundblad 1952: fig. 39E, typus of Torrenticola elgonensis [syn. to Monatractides elgonensis ]). Lundblad (1952) synonymized M. lemnia Lundblad, 1927 and M. elgonensis Lundblad, 1941 with M. ventriosus . It is worth mentioning that in 1941 Lundblad described a female from Kenya as subspecies stenostomoides, characterized by shorter ventral seta on P-4, not reaching the tip of P-5 (see Lundblad 1952, Fig, 40D). K.O. Viets (1965) reported a male of M. ventriosus stenostomoides from Transvaal, South Africa.

It is likely the species from our material from Ghana and from Liberia ( Cook 1966) represents the same, undescribed species. However, no illustration had been given of the ejaculatory complex by Cook (1966) for specimens from Liberia. Introducing a new species, in our opinion, will create more confusion given the present state of knowledge of this species.

Figures

FIGURE 23 A – E. Monatractides cf. ventriosus (K. Viets, 1916), male, Laboun River: A = dorsal shield; B = idiosoma, ventral view; C = palp, lateral view (P- 1 lacking); D = gnathosoma; E = ejaculatory complex. Scale bars = 100 Μm.

FIGURE 24 A – D. Monatractides cf. ventriosus (K. Viets, 1916), female, Agumatsa River: A = dorsal shield; B = idiosoma, ventral view; C = palp, medial view; D = frontal margin of idiosoma, dorsal view. Scale bars = 100 Μm.

FIGURE 25 A – I. Photographs of dorsal shield. A Monatractides acutiscutatus (K. Viets, 1914), female, unnamed creek upstream Sagyimase. B – C M. convexiscutata (K. Viets, 1958), stream Asukuma: B = male, C = female. D – E M. koenikei (K. Viets, 1916): D = male from Nubui River, E = female from Akaa Falls. F – G M. stigeophora (Cook, 1966), female: F = specimen from Supon stream, G = juvenile specimen from stream upstream Sagyimase. H – I M. cf. ventriosus (K. Viets, 1916): H = male from Laboun River, I = female from Agumatsa River.

FIGURE 26 A – I. Photographs of ventral shield. A Monatractides acutiscutatus (K. Viets, 1914), female, unnamed creek upstream Sagyimase. B – C M. convexiscutata (K. Viets, 1958), stream Asukuma: B = male, C = female. D – E M. koenikei (K. Viets, 1916): D = male from Nubui River, E = female from Akaa Falls. F – G M. stigeophora (Cook, 1966), female: F = specimen from Supon stream, G = juvenile specimen from stream upstream Sagyimase. H – I M. cf. ventriosus (K. Viets, 1916): H = male from Laboun River, I = female from Agumatsa River.

FIGURE 44 A – L. Photographs of ejaculatory complex: A Monatractides convexiscutata (K. Viets, 1958), male, Asukuma River. B M. melpomene n. sp., Amedzofe Falls. C M. euterpe n. sp., creek upstream Sagyimase. D M. cf. ventriosus (K. Viets, 1916), male, Laboun River. E – L Monatractides microstoma - species complex (E – G—Form '' A' ', H – L—Form '' B' '; E – H—ejaculatory complex reduced to sclerotized framework above the genital field, I – L ejaculatory complex slide-mounted): E, L = specimens from Tagbo River, F, H – K = specimens from Apkonu stream, G = specimen from Plunge pool Agumatsa Falls.

Tables

TABLE 3. Measurements of Monatractides cf. ventriosus (K. Viets, 1916) from Ghana.

Idiosoma L 578	552	681	694
Idiosoma W 458	441	572	575
Idiosoma L/W ratio 1.26	1.25	1.19	1.2
Ds L 498	478	594	606
Ds W 396	388	487	480
Ds L/W ratio 1.26	1.23	1.22	1.26
Dp L 453	426	547	557
Sh plate L 191–194	180–183	208–213	216
Sh plate W 70–71	66–69	78	77–78
Sh plate L/W 2.7–2.8	2.6–2.8	2.7	2.8
F plate L 97–103	97	103–106	105
F plate W 70	69	72–73	75–77
F plate L/W ratio 1.4–1.5	1.4	1.4–1.5	1.4
Sh pl L/f pl L ratio 1.9–2.0	1.9	2.0	2.06
Gnathosomal bay L 100	103	115	120
Cx-I L 238	214	250	256
Cx-I mL 138	111	134	136
Cx-II+III mL 73	68	63	72
Cx-1 L/Cx-II+III mL 3.3	3.2	4.0	3.6
Cx-I mL/Cx-II+III mL ratio 1.9	1.6	2.1	1.9
Genital field L 119	116	148	148
Genital field W 100	103	147	138
Gf L/W ratio 1.19	1.12	1.01	1.08
Dist gf—expo 116	113	141	153
Dist gf—cauda 144	153	219	219
Ec L 166	162	-	-
Gnathosoma vL 125	115	142	132
Chelicera L 149	157	177	175
Palp, total L 174–175	166	193–195	195–196
P-1 dL/H 18–19/21	20/20	21–22/22	21–22/22
P-2 dL/H 48/37	44/33	55/35	51/37
P-3 dL/H 34/28	31/25	40/30	37/29
P-4 dL/H 46/18–19	46/17	48–49/21	54/20
P-5 dL/H 28/11	25/11	29/14	32/12
P-1 dL/H ratio 0.89	1.0	0.97	0.98
P-2 dL/H ratio 1.29	1.33	1.58	1.38
P-3 dL/H ratio 1.26	1.21	1.33	1.27
P-4 dL/H ratio 2.5	2.7	2.3	2.7
P-5 dL/H ratio 2.6	1.7	2.1	2.7
dL P-2/P-4 ratio 1.03	0.96	1.14	0.94
I-L-4 L 79	80	95	94
I-L-5 L 77	75	88	89
I-L-6 L 82	77	90	89
I-L-6 H 36	33	34	31
I-L-6 L/H ratio 2.3	2.3	2.6	2.9