Ectomerus triquetrus Flechtmann & Etienne, 2002, n.sp.
Creators: name: Flechtmann, Carlos H. W.
name: Etienne, Jean
Publisher: name: Zenodo
Year: 2002
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Arachnida
Prostigmata
Eriophyidae
Ectomerus
Ectomerus triquetrus

description: Ectomerus triquetrus n.sp. (Fig. 3)
DIAGNOSIS ­ An Ectomerus species with an equilateral triangular prodorsal shield lobe, six­rayed empodia, scapular setae set on distinct tubercles and pointed upwards.
FEMALE ­ (n = 6). Idiosoma 177 (123­181), 49 (39­39) wide. Gnathosoma downcurved; basal seta 3 (3); antapical seta not discernible; chelicerae 16 (13­16). Prodorsal shield 30 (23­30) including lobe, 33 (26­33) wide; frontal lobe an equilateral triangle, 5 (3­6) long. Shield design a pattern of longitudinal lines, median line restricted to posterior third, admedian lines complete, broken; submedian and additional lines broken. Laterally with curved lines, in some specimens outlining an elongate oval spot. Dorsal shield tubercles distinct, near rear shield margin, 14 (11­14) apart, directing the 19 (18­20) long scapular setae (sc) upwards and slightly ahead (see remarks). Legs with all usual setae present; leg I 24 (18­24); femur 6 (5­6), femoral seta (bv) 9 (5­9); genu 3 (3­5), genual seta (l") 23 (14­23); tibia 5 (4­5), tibial seta (l') 5 (3­5); tarsus 5 (4­6), solenidium 4 (4­5), empodium 4 (4), 6­rayed, dorsal seta (ft') 5 (4­6), lateral seta (ft") 16 (16), unguinal seta (u') 4 (2­4). Leg II 22 (15­22); femur 7 (5­7), bv 7 (5­7); genu 3 (2­3), l" 10 (6­10); tibia 4 (2­3); tarsus 4 (3­ 5), solenidium 8 (7­8), empodium 5 (4­6), 6­rayed, ft' 4 (4­5), ft" 18 (16­18), u' 3 (2­3). Coxae unornamented except for a broke, curved, longitudinal line on coxa I. Coxae I with a short sternal line, 3 (3­4), forked to rear. Coxal seta I (1b) 8 (6­8), 6 (5­7) apart; coxal seta II (1a) 16 (17­19), 8 (6­9) apart; coxal seta III (2a) 30 (26­30), 17 (13­18) apart. Coxigenital area with 4 (3­4) microtuberculate annuli. Genitalia 19 (15­19) wide, 10 (9­10) long; epigynium with 12 (12­14) longitudinal ribs, more or less broken centrally; genital seta (3a) 11 (9­11). Genitalia somewhat appressed to coxae, anterior apodeme of internal genitalia shortened. Opisthosoma evenly rounded in cross section. Lateral seta (c2) 18 (17­19), on annulus 4 (3­4) from genitalia rear margin; ventral seta I (d) 46 (35­46), 33 (26­33) apart, on annulus 19 (11­18); ventral seta II (e) 41 (33­48), 20 (16­25) apart, on annulus 37 (24­37); ventral seta III (f) 18 (12­18), 15 (9­15) apart, on annulus 66 (42­59) or 6th from rear. Total ventral annuli 71 (48­64), beset with rounded microtubercles; total dorsal annuli 73 (44­70) with elongate microtubercles, plus 8 (9­14) caudal, wavy annuli with minute microtubercles on ring margin. Caudal seta (h2) 40 (40­46); accessory seta (h1) missing.
MALE ­ (n = 3). Smaller than female, 116­157, 36­47 wide. Gnathosoma: basal seta 2; antapical seta not discernible; chelicerae 14­15. Prodorsal shield 24­26, including 3­4 frontal lobe, 26­27 wide. Dorsal shield tubercles 12­18 apart, sc 16­18. Leg I 18­19; femur 5­6, bv 6­7; genu 3, l" 12­15; tibia 3­4, l' 2­3; tarsus 4, solenidium 4, empodium 4, 6­rayed, ft' 5­7, ft" 12­15, u' 1­2. Leg II 17­18; femur 6, bv 8; genu 2­3, l" 7­9; tibia 2­3; tarsus 3­4, solenidium 7, empodium 3­4, 6­rayed, ft' 4­5, ft" 15­16, u' 2­3. Coxae: 1b 6­11, 5­7 apart; 1a 11­15, 6­9 apart; 2a 23­26, 13­15 apart; coxisternal area with 3­4 microtuberculate annuli. Genitalia 13­15 wide, 8­12 long, smooth; 3a 8­9. Opisthosoma: c 2 14­18, on annulus 2­5; d 33­38, 26­33 apart, on annulus 10­12; e 27­33, 17­24 apart, on annulus 22­ 26; f 12­13, 10­13 apart, on annulus 39­49 or 6th from rear. Total ventral annuli 45­55; total dorsal annuli 34­58 with elongate microtubercles plus 11­14 annuli with minute marginal microtubercles. Caudal seta (h2) 28­35; h1 missing.
TYPE MATERIAL ­ female holotype, 58 female and 4 male paratypes, from Buchenavia capitata (Combretaceae), Les Abymes, Guadeloupe, coll. J. Etienne, 2 Sept. 2001, on 18 microscopic preparations in the collection of Departamento de Entomologia, Fitopatologia e Zoologia Agrícola, Universidade de São Paulo, ESALQ, Piracicaba, São Paulo, Brazil. One paratype slide deposited in the New Zealand Arthropod Collection.
RELATION TO HOST ­ the mites were collected from finger­like galls on leaves and vagrant in flowers.
ETYMOLOGY ­ The specific designation triquetrus is based on the Latin quetrus, a suffix meaning angled, cornered or sided; triquetrus refers to the triangular front lobe of the prodorsal shield.
REMARKS ­ 1.) In one male specimen the internal genital structures (Fig. 3, IGM) could be observed. Following the description given by Nuzzaci(1976), the ejaculatory duct (= vas deferens), a rather voluminous seminal vesicle, and two testicles are recognizable, on the contrary of only one testis as mentioned by Nuzzaci and Alberti (1996), Nuzzaci and Solinas (1984) and Nuzzaci (1976).
2.) The new species is the fourth known species in the genus Ectomerus. All four species were collected from plants in the family Combretaceae: E. anysis Keifer, l970, from
Terminalia muelleri in Australia, E. chebulae Mohanasundaram, 1980, from T. chebulae in India, E. systenus Meyer, 1990, from T. sericea in South Africa and the new species from Buchenavia capitata in Guadeloupe. These species can be separated by the shape of the frontal lobe: bluntly rounded distally in E. anysis, an equilateral triangle in the new species, ending in a thin, sharp, elongate point in E. chebulae and E. systenus. In E. chebulae the first setiferous coxal tubercles are in an advanced position near the inner corners of forecoxae, well ahead of anterior coxal approximation, while in E. systenus they are about level with anterior coxal approximation.
3.) The setiferous tubercles on prodorsal shield in E. triquetrus are soft and the scapular setae are directed up and forwards in the living specimens; in the process of microscopic preparations, according to the angle at which the coverslip is lowered, setae and tubercles are bent forwards, sidewards or even backwards.
description: Published as part of Flechtmann, Carlos H. W. & Etienne, Jean, 2002, New records of plant mites (Acari, Acaridae, Tetranychidae) from Guadeloupe and Marie Galante with descriptions of five new eriophyid species, pp. 1-16 in Zootaxa 47 on pages 7-10, DOI: 10.5281/zenodo.155892