Lyobia Livschits & Mitrofanov, 1971

Mirza, Jawwad Hassan, Elgoni, Nasreldeen Ahmed, Kamran, Muhammad & Alatawi, Fahad Jaber, 2025, Mites of the genus Bryobia (Acari, Tetranychidae): taxonomic notes on some species and a diagnostic key to the world species, ZooKeys 1239, pp. 51-73 : 51-73

Subgenus Lyobia Livschits & Mitrofanov, 1971

Type species.

Bryobia rubrioculus ( Scheuten) 1857: 104 .

Diagnosis

(based on females). As defined by Mirza et al. (2024).

Key to the 51 species of the genus Lyobia

Species groups definition is based on Mirza et al. 2024.

Notes on the species of the subgenus Lyobia

The subgenus Lyobia includes 58 species ( Mirza et al. 2024) but the key to only 51 species is provided above. The species B. (L.) ericoides Meyer, 1974 , belonging to the species group eurotiae , is excluded from the key due to leg I true claw morphology. The status of the remaining six species, all belonging to the species group rubrioculus , are discussed below.

Species group eurotiae

The two species in this species group B. (L.) eurotiae Mitrofanov, 1973 and B. (L.) pamirica Mitrofanov, 1973 , are morphologically similar and share the type host plant ( Eurotia sp. ), type locality ( Tadjikistan), and date of collection (23 July 1967). These two species share most morphological characteristics, including similar body length and width, lacking propodosomal lateral lobes, setae v 2 longer than v 1, slender setiform setae, length of leg I equal to body length, number of tenant hairs on leg empodia I-IV, and most of the leg chaetotaxy. The morphological characters which differentiate B. (L.) eurotiae from B. (L.) pamirica include state of propodosomal lobes (completely absent vs inner lobes joined from the middle, forming a cone), dorsal setal tubercles (indistinct vs distinct), leg chaetotaxy of femora I-III (9-7 - 4 vs 8-6 - 3), genua I and II (8-5 vs 4-4), and tibia II (9 vs 6), respectively. The differences in leg chaetotaxy mentioned above should be re-examined and could be considered as variations. The original description of B. (L.) eurotiae provides leg chaetotaxy in which tibia I has 24 setae. It appears that the setal count of tibia I was missed, and the setal counts for tarsus I were provided. It could be assumed that there are 24 setae on tarsus I, which was also described for B. (L.) pamirica because the chaetotaxy of tibiae II-IV is similar in both species. Similarly, the setae f 1 were described to be present sublaterally in B. (L.) pamirica , while they are illustrated as aligned with dorsocentral setae c 1. Hence, the setae f 1 are present centrally or subcentrally in B. (L.) pamirica , similar to B. (L.) eurotiae . Although there is evidence for the possible synonymy of these two species, it is important to re-examine the type specimens to reach a definitive conclusion.

Species group sarothamni

There are seven species in this species group ( Mirza et al. 2024). The morphology of propodosomal lobes has been described with variations. For instance, B. (L.) sarothamni Geijskes, 1939 , was originally described from the Netherlands, with the presence of four propodosomal lobes in the form of tubercles ( Geijskes 1939). Pritchard and Baker (1955) distinguished the English population of B. (L.) sarothamni with a complete absence of “ cephalic projections ”. Baker and Tuttle (1994) reported the presence of the propodosomal projection, where outer ones were as broad as long, and 1 / 3 as long as the inner pair. This situation is similar to that in the praetiosa species complex (in the subgenus Bryobia (B. )). It is recommended to approach the species in this species group with extreme caution, and morphological variations should be completely understood before describing new taxa.

Species group rubrioculus

There are 48 species included in this species group ( Mirza et al. 2024). The species B. (L.) cinereae Auger & Migeon, 2014 was placed in the species group sarothamni ( Mirza et al. 2024) . However, in the present study, it is included in the species group rubrioculus due to the marginal position of sacral f 1 and f 2 setae. This species is morphologically close to B. (L.) belliloci Auger, Arabuli & Migeon, 2015 ; however, the morphological differences are debatable. It has been stated that setae d 1 clearly surpass the bases of e 1 in B. (L.) belliloci (illustrated as just passing) while setae d 1 just reach the base of setae e 1 in B. (L.) cinereae ( Auger and Migeon 2014) . There are other morphological characters which were used to differentiate B. (L.) belliloci from B. (L.) cinereae including the depth of the inner lobe incisions (but illustrated as exactly same for both species), peritremal distal enlargement length (both anastomosing but length has 7 μm difference), length of internal seta l’ 1 on femur I, lengths and shapes of coxal setae 1 b and 1 c (discrepancies in the description and illustrations of B. (L.) belliloci ). These characters may reflect variations in the morphologies, especially when both species have the same host plant, Genista cinerae , and are both reported from France ( Auger and Migeon 2014; Auger et al. 2015). The species B. (L.) belliloci is excluded from the key, and perhaps further studies may suggest it as a junior synonym of B. (L.) cinereae .

The four species B. (L.) tiliae ( Oudemans, 1928; Germany), B. (L.) rubrioculus ( Scheuten, 1857; Germany), B. (L.) lonicerae Reck, 1956 ( Georgia), and B (L.) ulmophila Reck, 1947 ( Georgia), are very similar to each other in all morphological aspects including leg morphology. The species B. (L.) rubrioculus has been described and illustrated from different regions of the world and number of species have been synonymized under it ( Migeon and Dorkeld 2025). Frommer and Jorgensen (1972) studied the morphological and behavioral variations with host specificity of B. (L.) rubrioculus and distinctly separated this species from B. (L.) praetiosa . The two species B. (L.) lonicerae and B. (L.) ulmophila were morphologically compared with B. (L.) redikorzevi that is considered a synonym of B. (L.) rubrioculus by Frommer and Jorgenson (1972). Wainstein (1960) considered B. (L.) ulmophila as synonym of B. (L.) redikorzevi . The species B. (L.) tiliae was originally described as a type species of the genus Schmiedleinia Oudemans, 1928 , based on the larval specimens collected from the host plant Tiliae sp. in Germany ( Oudemans 1928). The genus was later synonymized with the genus Bryobia , and the species tiliae was considered as the larvae of B. praetiosa ( Oudemans 1930) . Bagdasarian (1957) described the species B. (L.) tiliae from Armenia on the same host plant, Tiliae sp. It was later considered a synonym of the species described by Oudemans (1928) (Wainstein 1960). In that synonymy, B. (L.) tiliae was considered to be morphologically close to B. (L.) ulmophila and B. (L.) redikorzevi ( Bagdasarian 1957) but distinguished based on the number of setae on leg femur I. Both of the latter two species have been considered as a synonym of B. (L.) rubrioculus . The leg chaetotaxy alone would not be sufficient to confidently validate the identity of the species. In light of this debate, it would be difficult to reach any definitive conclusion regarding the validity of these three species, and their synonymy with B. (L.) rubrioculus requires further investigation.

Eyndhoven and Vacante (1985) described 13 species belonging to the berlesei species group, eight of which were described for the first time. Among them, five species B. (L.) pandayi Eyndhoven & Vacante, 1985 , B. (L.) pyrenaica Eyndhoven & Vacante, 1985 , B. (L.) pelerentsi Eyndhoven & Vacante, 1985 , B. (L.) dikmenensis Eyndhoven & Vacante, 1985 , and B. (L.) provincialis Eyndhoven & Vacante, 1985 , have variable morphological characters. The three species B. (L.) pandayi , B. (L.) pyrenaica , and B. (L.) pelerentsi were considered close to each to other and the differential character designated as “ Each species has its own host plant ” ( Eyndhoven and Vacante 1985: 400). In all other morphological aspects, these three species resemble each other, and it is difficult to differentiate them. The remarks for these species were stated as “ For general remarks see Bryobia pandayi ”. It is important to mention that a species having its own host plant does not necessitate its validity. The species B. (L.) pandayi was reported from Calicotome spinosa . The same host plant ( Calicotome sp. ) harbors almost seven Bryobia taxa ( Migeon and Dorkeld 2025). Interestingly, B. (L.) pelerentsi is also reported from Calicotome sp. ( Eyndhoven and Vacante 1985). Hence, with this argument, the synonymy of B. (L.) pyrenaica and B. (L.) pelerentsi with B. (L.) pandayi appears undeniable. Similarly, both species, B. (L.) dikmenensis and B. (L.) provincialis are reported from the same host plant (Genistus sp.) and were morphologically designated close to each other by Eyndhoven and Vacante (1985). The only morphological difference described was that the second and third dorsocentrals were smaller than the other dorsal body setae in B. (L.) dikmenensis , while of similar length in B. (L.) provincialis . However, this contradicts what has been described for these setae based on 14 specimens ( Eyndhoven and Vacante 1985). This places the status of these species as doubtful, and there is an urgent need for re-analysis of the morphological characters of these species.

Figures

Figure 6. Shape of dorsal setae in adult female a palmate in Bryobia (Lyobia) alveolata Auger & Flechtmann, 2009 (redrawn from Auger et al. 2009) b fan-shaped in Bryobia (Lyobia) kakuliana Reck, 1956 (redrawn from Livschitz and Mitrofanov 1971) c spatulate in Bryobia (Allobia) birivularis Meyer, 1989 (redrawn from Meyer and Ueckermann 1989) d lanceolate in Bryobia (Lyobia) gushariensis Livschits & Mitrofanov, 1971 (redrawn from Livschits and Mitrofanov 1971) e setiform serrate in Bryobia (Lyobia) cinereae Auger & Migeon, 2014 (redrawn from Auger and Migeon 2014).