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New records of the genus Bryobia (Acari: Tetranychidae) from Syria with description of a new species

Barbar, Ziad1 and Auger, Philippe2

1✉ Department of Plant Protection, Faculty of Agriculture, Al-Baath University, P.O. Box 77, Al- Sham St., Homs, Syria.
2CBGP, INRAE, CIRAD, IRD, Montpellier SupAgro, Univ Montpellier, Montpellier, France.

2020 - Volume: 60 Issue: 2 pages: 268-288

DOI: 10.24349/acarologia/20204367
ZooBank LSID: 26A372EC-4BD0-40AB-AA7C-F98BF94299FA

Original research

Keywords

Tetranychid mite bryobiine mite new species new records

Abstract

Three species of Tetranychidae belonging to the genus Bryobia were collected from Latakia governorate, Syria in 2019: Bryobia (Allobia) syriensis n. sp. collected from Salvia verbenaca L., is described; Bryobia (Allobia) nikitensis and Bryobia (Bryobia) gigas collected from S. verbenaca and from soil litter, respectively, are reported. New observations of Bryobia specimens previously reported from the same governorate during 2014-2016 revealed that specimens of Bryobia (Bryobia) watersi were misidentified as Bryobia (Bryobia) graminum and Bryobia (Bryobia) kissophila. Among them, we found two aberrant females bearing three propodosomal lobes. By analogy, we discussed the cases of the trilobed species, Bryobia bakeri and Bryobia aegyptiacus, and concluded that they could be teratological forms of quadrilobed Bryobia species rather than species with a particular pattern of propodosomal lobes.


Introduction

Among the spider mite family, the genus Bryobia is the fourth largest genus in terms of species (Migeon and Dorkeld, 2019) and since the revision of the genus Pseudobryobia by Arabuli et al. (2019), it contains 143 taxa.

Several species belonging to this genus are worldwide distributed, polyphagous, and could be distinctly economically injurious to crops (Vacante, 2010). To date, seven species of the genus Bryobia are known from Syria: Bryobia (Allobia) nikitensis (Livshits and Mitrofanov), Bryobia (Bryobia) gigas Auger et al., B. (B.) graminum (Schrank), B. (B.) kissophila Eyndhoven, B. (B.) praetiosa Koch, B. (B.) vasiljevi Reck and B. (Lyobia) rubrioculus (Scheuten) (El-Hariri, 1968; Barbar, 2014, 2018; Zeity, 2017; Zeity and Srinivasa, 2019; Zriki et al., 2015). However, some specimens of this genus collected during 2014–2016 still remained unidentified (of which two specimens bearing only three propodosomal lobes each with one seta) and those of B. (B.) graminum and B. (B.) kissophila seem to be misidentified as the identification was based only on morphological characteristics of adult females (Barbar, 2014, 2018).

The aims of the current paper are to present the results of some field samplings of Bryobia species undertaken in Latakia governorate in 2019 and to re-examine all specimens of this genus collected in the same governorate over the period 2014–2016 and reported by Barbar (2014, 2018).

The description of a new species of Bryobia is provided. A new record, new host plants and the cases of misidentifications are reported. Finally, the observation of unusual Bryobia specimens' prodorsal lobes lead us to discuss the identity of Bryobia bakeri (Zaher, Gomaa and El-Enany, 1982) and Bryobia aegyptiacus (Zaher, Gomaa and El-Enany, 1982).

Materials and methods

Field sampling

Samplings of tetranychid fauna were conducted in Latakia governorate in April and June, 2019. Mites were collected from soil litter and from leaves of common weed species within a small forest (about six hectares, 57 m above the sea level) of Pinus halepensis Mill. located at Attabiyyat (35°30'24'' N, 35°46'49'' E) in the south-western Latakia city, Syria. Mites were removed from leaves using the ''dipping-checking-washing-filtering'' method (Boller, 1984). For collecting mites from litter, materials were placed on a sieve (25 cm Ø x 10 cm; its screen with 5 mesh/cm) and shaken over a black plastic sheet (1.5 m2). Collected mites were cleared in lactic acid for 48 hours, mounted on slides in Hoyer's medium, and then dried in an oven at 40 °C for three days.

Mite observation and description

The specimens were examined using an Olympus® CH20 microscope. Measurements were realized using the scale of a reticle installed on the eyepiece lens. Mite body parts of specimens were pictured using a mobile phone camera (13 megapixels) fixed on the eyepiece lens and images were transferred to the professional quality vector graphics software Inkscape ® 0.92 installed on a computer for drawing with the aid of the computer's mouse.

All measurements are given in micrometers (µm) and the setal nomenclature used in the description follows Lindquist (1985). The holotype measurements are followed by measurements of the range of paratypes in parentheses. In addition to the key body measurements such as the distance between setae v2 and setae h1 and members of setae sc2 (Saito et al., 1999), body length representing the distance between the tip of palps to the end of idiosoma and body width representing the widest transverse part of the hysterosoma, are also provided. The distance between two setae was measured as the distance from the center of one setal base to the other. Legs were measured from coxae to the distal margin of tarsi (excluding claws and empodia). Leg setal counts are given in the order: coxa-trochanter-femur-genu-tibia-tarsus. Numbers of setae refer to tactile setae, solenidia are given in parentheses and alternative counts are given in brackets. When asymmetry in number of setae on a leg segment was present, only the maximal number was considered.

Systematics

Family Tetranychidae Donnadieu, 1875

Subfamily Bryobiinae Berlese, 1913

Tribe Bryobiini Reck, 1952

Genus Bryobia Koch, 1836

Bryobia (Allobia) nikitensis Livshits and Mitrofanov, 1969

Two female specimens of this species were recorded on a new host plant: it was found on Salvia verbenaca L., Attabiyyat, south-west of Latakia city, Syria (35°30'24'' N, 35°46'49'' E, 23 April 2019). This species has been previously collected from Sarcopoterium spinosum (L.) in Syria (Barbar, 2018; Zeity and Srinivasa, 2019).

Bryobia (Allobia) syriensis n. sp.

ZOOBANK: A423D4AA-D815-4BEF-94B8-47FD082F3ED3

Figure 1. Bryobia syriensis n. sp., female: A – dorsal aspect; B – dorsal seta c1. Scale bars = 100 µm (A), 10 µm (B).

Figure 2. Bryobia syriensis n. sp., female: A, B, C – variation in propodosomal lobes; D – detail of the prodorsal striation of the area immediately anterior to setae c1. Scale bars = 20 µm (A, B, C), 30 µm (D).

Figures 1–10

Type material — Holotype (female), 23 female and 2 male paratypes on 10 microscopic preparations, from S. verbenaca, Attabiyyat, south-west of Latakia city, Syria (35°30'24'' N, 35°46'49'' E), 23 April and 2 June, 2019, coll. Z. Barbar. The holotype and paratypes are deposited in the Arthropod Collection of the Department of Plant Protection, Faculty of Agriculture, Albaath University, Homs, Syria.

Diagnosis — This species belongs to Bryobia (Allobia) Livshitz and Mitrofanov (1971) which is characterized by the following: propodosomal lobes absent or poorly developed, if present, outer and inner lobes not separated by deep incision; distance between f1 members longer than distance between f2 members; f1 and f2 well separated laterally. It can be distinguished from others Byrobia species by a combination of the following characteristics: females with weakly developed median propodosomal lobes with small and shallow incision, outer lobes reduced to very small tubercles; setae v2 about twice as long as setae v1; dorsal body setae short, spatulate, serrate and inserted in small tubercles; peritreme ends in a tiny anastomosis consisting of 3–4 loges; tarsus III with tactile seta and solenidion subequal in length forming duplex; tarsus IV with solenidion well-separated from tactile, proximal, about 3/4 the length of tactile; leg I shorter than body length, empodial claws I-IV uncinate, each with one pair of tenent hairs; empodium I with one pair of tenent hairs and empodia II-IV with two rows of tenent hairs.

Female description — (n = 24). Relatively small, 548 (488–548) long excluding gnathosoma, 663 (575–663) including gnathosoma, and 384 (327–384) wide.

Dorsum – Prodorsum with four pairs of setae (Figure 1A); median propodosomal lobes weakly developed with fused base (variations in propodosomal lobes due to mounting are presented in Figure 2A-C); outer propodosomal lobes reduced to small tubercles; setae v2 about twice as long as setae v1 (Figure 2). Distance between members of first (v1) and second (v2) pair of propodosomal setae insertions 10 (8–12) and 47 (45–50), respectively. Dorsal body setae short, spatulate and serrate, 12–17 width, subequal in length except for v1 far smaller, inserted on small tubercles (Figure 1B). Measurements of dorsal setae: v1 11 (10–11); v2 23 (22–26); sc1 21 (21–25); sc2 23 (21–25); c1 25 (23–29); c2 23 (21–26); c3 23 (21–25); d1 23 (21–25); d2 23 (21–25); d3 23 (21–23); e1 23 (21–23); e2 23 (21–23); e3 23 (21–23); f1 23 (21–25); f2 21 (21–23); h1 18 (18–23). Distances between setae: sc2–sc2 237 (202–237), c1c1 83 (64–83), d1d1 60 (55–64), e1e1 51 (41–51), f1f1 148 (126–148), f2f2 115 (110–115), h1h1 46 (40–50), c1d1 101 (81–101), d1e1 81 (69–81), v2h1 535 (470–535). Setae f1 and f2 lateral, distance between f1 members larger than between f2 members. Dorsal body surface granulated with longitudinal and irregular folds on propodosoma (Figure 2D) and with transverse spaced granulate striae on medial hysterosoma irregularly arched posteriorly (Figure 1).

Gnathosoma – Stylophore slightly notched anteriorly, longer than wide (Figure 3A). Tibial claw of palpus bidentate. Palptarsus smaller than tibial claw, with three tactile setae, three eupathidia and one solenidion; eupathidia and solenidion subequal in length (Figure 3B). Peritreme ends in a tiny bulbous anastomosis (about 7 in diameter) consisting of 3–4 loges (Figure 3C).

Figure 3. Bryobia syriensis n. sp., female: A – stylophore; B – palpal tibia and tarsus; C – peritreme; D – spermatheca. Scale bars = 50 µm (A), 10 µm (B, C), 15 µm (D).

Venter – Striation transverse, sparse and broken between 1a and 3a pairs of setae, irregularly longitudinal, sparse and broken between 3a and 4a pairs of setae, transverse and broken between 4a and aggenital (ag) pairs of setae, irregular in the area anterior to genital flap and longitudinal between (ag) setae. Genitoanal region with two pairs of genitals (g1-2), three pairs of pseudanal (ps1-3) and two pairs of ventrocaudal (h2-3) setae. Sacculus of spermatheca elongate, with smooth surface, seems constricted in its distal third, 15 (15–16) long, 7 (6–7) wide (Figure 3D).

Legs – (Figures 4, 5, 6). Leg I shorter than body length, 389 (381–391) long, leg II 290 (253–290), leg III 290 (255–290), leg IV 306 (299–322). Length of segments of leg I as follows: trochanter 18 (18–24), femur 115 (108–115), genu 64 (57–69), tibia 74 (64–78), tarsus 69 (60–69). Leg setal counts as follows:

Figure 4. Bryobia syriensis n. sp., female: A – tibia and tarsus I; B – femur and genu I; C – tibia and tarsus II; D – femur and genu II. Scale bar = 50 µm (A, B, C, D).

Figure 5. Bryobia syriensis n. sp., female: A – tibia and tarsus III; B – femur and genu III; C – tibia and tarsus IV; D – femur and genu IV. Scale bar = 50 µm (A, B, C, D).

Figure 6. Bryobia syriensis n. sp., female: A – claw and empodium I; B – claw and empodium II; C – duplex setae on tarsus III; D – solenidion and associated tactile seta on tarsus IV; E – coxisternal setae 1b and 1c. Scale bars = 10 µm (A, B), 20 µm (C, D), 25 µm (E).

I: 2 – 1 – 14[15] – 8 – 13 + (1) – 18 + (3) + 2 duplexes

II: 1 – 1 – 10 – 5 – 9 – 15 + (1) + 1 duplex

III: 1 − 1 − 6 – 6 – 9 –14 + 1 duplex

IV: 1 – 1 – 5 – 6 – 9 − 14 + (1)

True claws uncinate, each with one pair of tenent hairs. Empodium I with one pair of tenent hairs, empodia II-IV each with two rows of tenent hairs (Figure 6A, B). Tarsus III associated tactile seta and solenidion forming duplex sub-equal in length (Figure 6C), on tarsus IV solenidion well-separated from tactile, proximal, about 3/4 the length of tactile (Figure 6D). Coxisternal setae 1b, 44, smooth about twice as long as setae 1c, 24, serrate (Figure 6E).

Male description — (n = 2). Small, 311–317 long excluding gnathosoma and 366–377 including gnathosoma, 207–210 wide.

Figure 7. Bryobia syriensis n. sp., male: A – dorsal aspect; B – dorsal seta c1; C – dorsal seta e1. Scale bars = 50 µm (A), 20 µm (B, C).

Dorsum – Without prodorsal projections, setae v1 and v2 located on tiny tubercles (Figure 7A). Setae v1 and v2 short, subspatulate, serrate, v2 twice as long as v1 (Figure 8A). Distance between first (v1) and second (v2) pair of propodosomal setae insertions 14–18 and 54–56, respectively. Other dorsal body setae subequal in length, elongate subspatulate, enlarged distally (setae c1 less enlarged), serrate, all inserted on tiny tubercles (Figure 7B, C). Dorsocentral setae (c1, d1 and e1) shorter than distances between consecutive setae. Measurements of dorsal setae: v1 7; v2 14–15; sc1 28; sc2 28–32; c1 30–35; c2 30–35; c3 28; d1 28–30; d2 28–30; d3 28; e1 30–32; e2 30–32; e3 28–30; f1 25–30; f2 30; h1 23. Distances between setae: sc2–sc2 150–170, c1c1 55–60, d1d1 41–51, e1e1 23–25, f1f1 64–68, f2f2 48–53, 64–68, h1h1 20, c1d1 44–48, d1e1 39–46, v2h1 274–304. Dorsal body surface granulate with few longitudinal and irregular folds on propodosoma, with transverse spaced striae on medial hysterosoma, and with arched striae on the surface between d1d3 and e1e3 (Figures 7A).

Figure 8. Bryobia syriensis n. sp., male: A – propodosomal lobes; B – palpal tibia and tarsus; C – peritreme; D – aeadeagus. Scale bars = 20 µm (A), 10 µm (B, C, D).

Gnathosoma – Stylophore slightly notched anteriorly, longer than wide, as in female. Tibial claw of palpus bidentate. Palptarsus as in female with solenidion shorter than eupathidia (Figure 8B). Peritreme ends in small bulb with four pointed denticles at its distal margin (Figure 8C).

Aeadeagus – Without knob, bent dorsad near at right angle, weakly sigmoid, with tapering distal part and acute tip pointing caudad, shaft dorsal margin curved (Figure 8D).

Legs – (Figures 9, 10). Leg I longer than body length 451 long, leg II 290–304, leg III 260–281, leg IV 288–304. Length of segments of leg I as follows: trochanter 18–23, femur 133–150, genu 69–76, tibia 81, tarsus 81. Leg setal counts as follows:

Figure 9. Bryobia syriensis n. sp., male: A – tibia and tarsus I; B – femur and genu I; C – tibia and tarsus II; D – femur and genu II. Scale bar = 50 µm (A, B, C, D).

Figure 10. Bryobia syriensis n. sp., male: A – tibia and tarsus III; B – femur and genu III; C – tibia and tarsus IV; D – femur and genu IV. Scale bar = 50 µm (A, B, C, D).

I: 2 – 1 – 14[15] – 8 – 13 + (1) – 18 + (8) + 2 duplexes

II: 1 – 1 – 10[11] – 6[5] – 9 – 15 + (1) + 1 duplex

III: 1 – 1 – 7 – 6 – 9 – 14 + 1 duplex

IV: 1 − 1 − 5 – 6 – 9 – 14 + (1)

True claws uncinate. Claws I-IV each with one pair of tenent hairs. Empodia I-IV each with two rows of tenent hairs. Tarsus III associated tactile seta and solenidion forming duplex sub-equal in length; tarsus IV with solenidion well-separated from tactile, proximal, about 2/3 the length of tactile.

Etymology — This species was named after the country, Syria, where it was collected.

Remarks — Among the species that belong to the subgenus Bryobia (Allobia) (as defined by Livshitz and Mitrofanov, 1971) to which B. (A.) syriensis n. sp. also belongs, it is very close to B. (A.) livschitzi Mitrofanov and Strunkova, 1968 (Livshitz and Mitrofanov, 1971), B. (A.) ziziphorae Strunkova and Mitrofanov, 1983, B. (A.) tuttlei Smiley and Baker, 1995, B. (A.) reckiana Mitrofanov and Strunkova, 1968, B. (A.) strunkovae Mitrofanov, 1968 (Livshitz and Mitrofanov, 1971), B. (A.) montana Mitrofanov, 1973 and B. (A.) giannitensis Hatzinikolis and Panou, 1996. However B. (A.) syriensis differs from B. (A.) livschitzi by having dorsal body setae spatulate (vs. subsaptulate with pointed or rounded tip in B. (A.) livschitzi); by differences in femoral setal count 14[15] – 10 – 6 – 5 and 12 – (7-8) – 4 – 4 in B. (A.) syriensis and B. (A.) livschitzi, respectively; and by differences in tibial setal count on legs II-IV, 9 – 9 – 9 and 7 – 7 – 7 in B. (A.) syriensis and B. (A.) livschitzi, respectively.

Bryobia (A.) syriensis can be separated from B. (A.) ziziphorae by the following characters: the outer prodorsal lobes are more developed in B. (A.) ziziphorae and the shape of setae v2 is also different; the distal end of the peritreme consists of a tiny anastomosis of 3–4 loges in B. (A.) syriensis whereas it is simple in B. (A.) ziziphorae; solenidion and tactile seta on tarsus IV are well–separated in B. (A.) syriensis vs. a duplex setae is present in B. (A.) ziziphorae; and the femoral, tibial and tarsal setal counts obviously differ between the two species.

The main differences between females of B. (A.) syriensis and B. (A.) tuttlei are the following: the outer propodosomal lobes are very reduced in B. (A.) syriensis but well developed in B. (A.) tuttlei; setae v1 are about half the length of v2 in B. (A.) syriensis whereas they are quite similar in size in B. (A.) tuttlei; the spermatheca has a smooth surface in B. (A.) syriensis vs. reticulate in B. (A.) tuttlei; obvious differences in leg setal counts are observed between the two species (with the exception of genu II and femur IV). In the male of B. (A.) syriensis dorsal body setae are elongated, subspatulate but in males of B. (A.) tuttlei they are spatulate (similar to those of female).

Bryobia (A.) syriensis clearly differs from B. (A.) reckiana by having spatulate, serrate and distally rounded dorsal body setae vs. lanceolate in B. (A.) reckiana; solenidion and tactile seta on tarsus IV are well-separated in B. (A.) syriensis vs. a duplex seta is present in B. (A.) reckiana; the empodium I of B. (A.) syriensis bears only one pair of tenent hairs whereas two rows of tenent hairs are present in B. (A.) reckiana; leg setal counts are very different between the two species.

Bryobia (A.) syriensis and B. (A.) strunkovae can be separated by: a smaller body width of B. (A.) syriensis, 327–384 vs. 572 in B. strunkovae; the leg I length that is far shorter (381–391) than the body length in B. (A.) syriensis whereas it is about as long as the body length (640) in B. (A.) strunkovae; the distal end of the peritreme is less developed in B. (A.) syriensis than in B. (A.) strunkovae; solenidion and tactile seta on tarsus IV are well-separated in B. (A.) syriensis but a duplex seta is present in B. (A.) strunkovae; finally, obvious differences between the setal counts of the two species are present.

Bryobia (A.) syriensis differs from B. (A.) montana by having one pair of tenent hairs on empodium I vs. two rows in B. (A.) montana; solenidion and tactile seta on tarsus IV are well–separated in B. (A.) syriensis vs. a duplex seta is present in B. (A.) montana; and by very different leg setal counts.

The main differences between B. (A.) syriensis and B. (A.) giannitensis are: a smaller body size of B. (A.) syriensis, 575–663 long and 327–384 wide vs. 789–809 and 650–559; a far shorter leg I in B. (A.) syriensis (381–391) compared to B. (A.) giannitensis (603–609); setae v1 and v2 are spatulate in B. (A.) syriensis but lanceolate in B. (A.) giannitensis; in B. (A.) syriensis one pair of tenent hairs is present on claws II-IV but each of them bears two pairs of tenent hairs in B. (A.) giannitensis; obvious differences in leg setal counts between the two species are also observed.

Bryobia (Bryobia) gigas Auger, Arabuli and Migeon, 2015

Four females of this species were collected from soil litter, Attabiyyat, south-west of Latakia city, Syria (35°30'24'' N, 35°46'49'' E), 23 April 2019. This species has been already collected from Bituminaria bituminosa (L.) in Syria (Zeity and Srinivasa, 2019) but this host plant was no present in the place where we collected these specimens.

Bryobia (Bryobia) watersi Manson, 1967

The specimens of this species were identified as Bryobia sp. and misidentified as B. (B.) graminum and/or B. (B.) kissophila in previous studies (Barbar, 2014, 2018). This was due to species identification only based on the morphological characteristics of females and particularly on variations in the shape of propodosomal lobes. In the present study, comparisons of all the specimens collected (including females, a male and juveniles, Figures 11-15) with the detailed redescriptions of B. (B.) graminum, B. (B.) kissophila and B. (B.) praetiosa by Mathys (1957) and the original description of B. (B.) watersi by Manson (1967) were undertaken. This led us to the conclusion that the morphological characteristics of the Syrian specimens fit well with those provided in the original description of B. (B.) watersi by Manson (1967) even if few morphological small differences were found: the dorsal body setae are slightly longer in Syrian females (there are no obvious differences in juveniles); genu II and tarsus IV of Syrian females with 6 and 14 setae respectively vs. 5 and 15 setae; genu II-III of Syrian male with 6 – 5 setae vs. 4[5] – 6; and tarsus III of Syrian deutonymphs with 10 setae vs. 11[12].

Figure 11. Bryobia watersi, female: A-D – variations in propodosomal lobes. Scale bars = 25 µm (A, B, C, D).

Figure 12. Bryobia watersi, female: A-D – variations in spermatheca. Scale bars = 20 μm (A, B, C, D).

Figure 13. Bryobia watersi, male: propodosomal lobes. Scale bar = 25 µm.

Figure 14. Bryobia watersi, immature stages: A – dorsal seta e1 of larva; B-C – propodosomal lobes of protonymph; D – propodosomal lobes of deutonymph. Scale bars = 20 µm (A), 50 µm (B, C, D).

Figure 15. Bryobia watersi, female: A-B – trilobed propodosomal lobes. Scale bars = 50 µm (A, B).

Remarks — This species was collected from several host plants surrounding a citrus orchard located at Al-ya'robiyah, Latakia governorate, Syria (35°30'24'' N, 35°48'33'' E) and was found on: Amaranthus retroflexus L., a new host plant (five females, 15 April 2014, previously identified as Bryobia sp.), Malva sylvestris L. (five females, two deutonymphs, three protonymphs and two larvae, 1 January 2014; four females, 15 February 2014; three females, 7 April 2015; two females, two protonymphs and one larva, 18 February 2016, previously misidentified as B. (B.) graminum; six females and one larva, 16 April 2016, previously misidentified as B. (B.) kissophila), Urtica urens L., a new host plant (three females and one protonymph, 15 April, 2014, previously identified as Bryobia sp.) and Trifolium sp., a new host plant (four females, three deutonymphs and one male, 14 April, 2015, previously identified as Bryobia sp.).

Among the specimens of B. (B.) watersi mentioned above, two females collected from A. retroflexus have only three propodosomal lobes each with a single seta (Figures 15 A-B). Initially, the specific identification of these specimens led to a result that they are either new specimens (or closely related species) of the two ''trilobed'' species B. bakeri Zaher et al. (1982) and B. aegyptiacus Zaher et al. (1982) or they are aberrant Bryobia specimens. Actually, the overall propodosomal lobe shapes of the trilobed Syrian specimens are closer to those of B. bakeri (Figure 15A) than those of B. aegyptiacus. Nevertheless, the Syrian specimens differ from those two species by the palptarsus setal count [unusual counts are found in the two species described by Zaher et al. (1982)] and by small differences in the global leg setal counts. These results led to conclude that the Syrian trilobed specimens did not belong to B. bakeri nor to B. aegyptiacus.

Indeed, despite the differences between the propodosomal lobes of the specimen presented in Figure 15B (typical of abnormal ''asymmetrical'' lobes; the outer lobe of the left side is obviously missing) and those of the specimen presented in Figure 15A (the axis of symmetry passes through the middle of the single inner lobe), we concluded that these females are abnormal individuals of B. (B.) watersi for several reasons:

• (1) Both specimens are morphologically identical to B. (B.) watersi [i.e. having similar leg ambulacra, leg chaetotaxy and articles dimensions, same shape and length of dorsal body setae and peritreme etc.].

• (2) Both specimens were collected together with specimens of B. (B.) watersi (same host plant, same date and place of collection).

• (3) Several attempts carried out in 2015 and 2016 to re-collect additional trilobed individuals (in the same location where they were collected first) were unsuccessful and all re-collected individuals were B. (B.) watersi.

• (4) Propodosomal lobe aberrations have already been reported in several Bryobia species (Arabuli and Auger, 2016; Fashing et al. 2016; Smiley and Baker, 1995).

This variability in the propodosomal lobe shape found in the two Syrian trilobed individuals of B. (B.) watersi guided us to question about the taxonomical value of the number of propodosomal lobes used to separate B. bakeri and B. aegyptiacus from other Bryobia species. Several arguments tend to show that these specimens could be teratological forms rather than species with a particular propodosomal lobes pattern:

• (1) Specimens are rare: like the Syrian trilobed specimen of B. (B.) watersi of the Figure 15A, only one specimen of B. bakeri and one of B. aegyptiacus are known. Although Smiley and Baker (1995) reported a possible additional female of B. bakeri, it could belong to another species because its leg setal count is far different from that of the type specimen of B. bakeri (it shares the same setal count only on five leg articles; as a comparison, the Syrian trilobed B. (B.) watersi are closer to B. bakeri for the reason that they share the same setal count on 12 leg articles).

• (2) Specimens with three propodosomal lobes (each bearing one seta) are known to occur in several species of Bryobia: Smiley and Baker (1995) mentioned that in a few species of Bryobia some aberrant females (with two or three propodosomal lobes) appear sometimes. Since that work, several cases of Bryobia species with three propodosomal lobes have been reported (Arabuli and Auger, 2016; Fashing et al. 2016). In the detailed study by Fashing et al. 2016, it was demonstrated that both morphotypes (with three or four propodosomal lobes) of Bryobia abyssiniae Fashing and Ueckermann, 2016 belong to the same species, and about 9.5% of observed specimens had a single propodosomal inner lobe (with a single seta v1).

• (3) The two Syrians trilobed specimens are conspecific despite the fact that one of them is obviously an aberrant form (asymmetry) and the other has a symmetrical propodosomal lobe pattern similar to that found in B. bakeri.

This tends to show that a bryobiine mite with an unpaired inner propodosomal lobe bearing a unique seta v1, can be an aberrant specimen despite a symmetrical propodosomal trilobed lobe pattern.

In our opinion, all these elements together strongly suggest that B. bakeri and B. aegyptiacus would be more aberrant individuals of two species of Bryobia (four-lobed) than species characterized by unpaired inner propodosomal lobe. Even if the data are insufficient to assign these ''trilobed'' species to an existing four-lobed Bryobia species, the demonstration presented here is consistent with the synonymy of the genus Septobia with the genus Bryobia by Bolland et al. (1998).

Acknowledgements

The first author would like to thank Professor Hassan Khalil for his valuable help in the identification of host plants. Thanks are due to Dr. Mahran Zeity and Dr. Mohamed W. Negm for supplying scientific papers to the first author.

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Date received:
2019-10-18
Date accepted:
2020-03-17
Date published:
2020-03-19

Edited by:
Migeon, Alain

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This work is licensed under a Creative Commons Attribution 4.0 International License
2020 Barbar, Ziad and Auger, Philippe

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