Tetranychus (Tetranychus) musae, Auger & Migeon & Flechtmann, 2008

Auger, Philippe, Migeon, Alain & Flechtmann, Carlos H. W., 2008, Description of a new Tetranychus (Acarina, Prostigmata: Tetranychidae) pest of Musa from French Guiana, Journal of Natural History (J. Nat. Hist.) 42 (27 - 28), pp. 1885-1892 : 1886-1890

Tetranychus (Tetranychus) musae sp. nov.

( Figures 1–3 )

Type material

Holotype. Institut National de la Recherche Agronomique (INRA), Centre de Biologie et de Gestion des Populations (CBGP), 34988 Montferrier-sur-Lez, France, from Musa sp. ( Musaceae ), Matoury, French Guiana, October 2005.

Paratypes. INRA, CBGP, 34988 Montferrier-sur-Lez, France, eight males, six females and seven nymphs, from Musa sp. ( Musaceae ), Matoury, French Guiana;

Muséum national d’Histoire naturelle, Paris (MNHN), two males, two females and two nymphs, from Musa sp. ( Musaceae ), Matoury, French Guiana.

Diagnosis

Among members of Tetranychus from the sixth group as defined by Flechtmann and Knihinicki (2002) (one tactile setae proximal to and three tactile setae in line with proximal duplex setae of tarsus I, empodial dorsomedian spur obvious), this species is distinctive by the shape of the aedeagus. It is quite close to that of Tetranychus yusti McGregor 1955 , placed in the seventh group by Flechtmann and Knihinicki (2002) (one tactile setae proximal to and three tactile setae in line with the proximal duplex setae of tarsus I, empodial dorsomedian spur tiny or absent), but differs from the latter in that the axis of the knob of the aedeagus and the shaft form an acute angle. Moreover, empodia II–IV bear obvious mediodorsal spurs and the terminal sensillum is nearly as long as broad, instead of tiny mediodorsal spurs and a terminal sensillum about two and a half times as long as broad in T. yusti . The aedeagus of T. musae also resembles that of Tetranychus tumidus Banks 1900 . However in this last species its axis does not form an angle (or a very small one) with the axis of the shaft and the anterior projection is not so developed compared to the posterior, which is not directed downward as in this new species. Moreover, the setal pattern of tarsus I of T. tumidus corresponds to species belonging to the eighth group in the key to the major groups of Tetranychus .

Description of the male

Holotype 415 Mm long (including gnathosoma).

Gnathosoma. The palptarsus terminal sensillum is about one and a fifth times as long as broad. The peritreme is hooked distally.

Dorsum. Dorsal body setae (lenght of holotype and variations of ten paratypes): v 2 55 (52–60); sc 1 103 (95–104); sc 2 69 (65–73); c 1 86 (87–90); c 2 86 (82–90); c 3 85 (81–89); d 1 88 (83–91); d 2 81 (87–95); e 1 (82–92); e 2 (89–96); f 1 (57–67); f 2 48 (44–53); h 1 21 (19–23). A few irregular lobes on opisthosomal striae are found between setae sc 1 and e.

Venter. Ventral striae without lobe.

Legs. Empodium I consists of a double claw-like structure with a strong mediodorsal spur about one half of the apppendages. Empodia II–IV bear three pairs of proximoventral hairs and a large mediodorsal spur about one half the length of proximoventral hairs. Leg chaetotaxy as follows (number of setae refers to tactile setae and sensory setae are given in parentheses):

I. 2212102529+(4)213+(3)+2 duplexes;

II. 221262527213+(1)+1 duplex;

III. 12124242629+(1);

IV. 121242427210+(1).

Aedeagus. The shaft of the aedeagus curves upward. The knob of the aedeagus is about two and a half times the width of the stem. The knob consists of an acute posterior projection bent ventrally and a larger anterior rounded projection directed anterodorsally forming a small depression on the dorsum. Its axis forms an acute angle with the axis of the shaft.

Description of the female

Eight females measured. Idiosoma: length 348–453 Mm, gnathosoma 106–123 Mm, width 283–314 Mm.

Gnathosoma. Palpus with a spinneret as long as broad. The peritreme is hooked distally.

Dorsum. Dorsal body setae are lanceolate, longer than distances between bases of consecutive setae (variations of 8 paratypes): v 2 71–80; sc 1 128–149; sc 2 95–101; c 1 117–143; c 2 118–131; c 3 112–130; d 1 121–138; d 2 114–140; e 1 112–136; e 2 116–138; f 1 109–124; f 2 83–101; h 1 38–48. The hysterosomal striation is transverse except between the bases of setae e 1 and f 1 (longitudinal) forming a diamond-shaped pattern between these setae. Dorsal hysterosomal striae with lobes rounded and broader than tall.

Venter. The area immediatly anterior to genital flap has broken longitudinal striae partly dash-like. The genital flap has transverse arched striae. Rounded lobes broader than tall are present. One pair of paranal setae is present.

Legs. Empodia I–IV bear three pairs of proximoventral hairs and large mediodorsal spurs about one half the length of proximoventral hairs. Leg chaetotaxy as follows (number of setae refers to tactile setae and sensory setae are given in parentheses):

I. 2212102529+(1)213+(1)+2 duplexes;

II. 221262527213+(1)+1 duplex;

III. 12124242629+(1);

IV. 121242427210+(1).

Tarsus I with one tactile setae proximal to proximal duplex setae with three tactiles in line or almost in line with proximal duplex setae. Solenidion is at or near the level of the proximal duplex.

Etymology

The species designation, musae , refers to the host plant on which mites were collected.

Biological observations

Adults of this species are orange-brown in colour with clear legs and they produce webbing. Feeding by this species causes browning and necrosis of the affected leaf areas. Outbreaks of this species require spraying of specific acaricides to avoid leaf burning of infested banana leaves.

Identification key

The 15 species recorded on Musa from South America belong to the subgenus Tetranychus sensu stricto as defined by Tuttle and Baker (1968). Construction of the key below is based on data of Migeon and Dorkeld (2006). It is also mainly based on the key to the major groups of Tetranychus of Flechtmann and Knihinicki (2002).

Figures

Figure 1. Tetranychus musae sp. nov., female. (A) Dorsal aspect (scale bar5125 Mm,1 div.525 Mm); (B) genital area (scale bar550 Mm, 1 div.510 Mm).

Figures 2. Tetranychus musae sp. nov., male. (A) Tarsus and tibia I; (B) tarsus and tibia II; (C) empodium I; (D) empodia II–IV; (E) palptarsus; (F) peritreme; (G) aedeagus (enlarged) (scale bar550 Mm, 1 div.510 Mm).

Figures 3. Tetranychus musae sp. nov., female. (A) Tarsus and tibia I; (B) tarsus and tibia II; (C) empodia I–IV; (D) palptarsus; (E) peritreme (scale bar550 Mm, 1 div.510 Mm).