Caeculisoma Berlese, 1888

Xu, Si-Yuan, Yi, Tian-Ci, Guo, Jian-Jun & Jin, Dao-Chao, 2019, A new species of larval Caeculisoma (Acari: Erythraeidae: Callidosomatinae) ectoparasitic on insects from China and a revised generic diagnosis, Zootaxa 4604 (3), pp. 511-524 : 512

Caeculisoma Berlese, 1888

Type species: Caeculisoma tuberculatum Berlese, 1888

Amended diagnosis. Larva: One eye on each side. Dorsal scutum generally rounded, but anterior margin maybe convex, concave, straight, or sinuous. ASE usually between ML and PL scutulae, sometimes level with PL ( C. penlineatus sp. nov.). PL at mid-point or in posterior half of scutum, PSE at posterior edge of scutum. Three pairs of normal setae (scutalae) with fine barbs on scutum. Ventral setae: paired sternalae I between coxae I; paired sternalae II between coxae II; one or two pairs of sternalae III between coxae III. Pedocoxalae 1, 2, 2. Pedotrochanteralae 1, 1, 1. Pedal tarsus with lateral claws dissimilar. Claw-like empodium falciform, overreaching the lateral claws.Anterior claw strong, falciform, simple or with few ciliations. Posterior claw pulvilliform with strong terminal hook. Palpal tibial claw bifurcate.

Remarks. The diagnosis for larvae of Caeculisoma is based on Southcott (1972). The most important difference is the location of anterior sensilla (ASE) in the genus, which Southcott (1972) used to separate Callidosoma (ASE anterior to ML) and Caeculisoma (ASE posterior to ML). Southcott’s diagnosis for Caeculisoma is generally applicable to C. penlineatus sp. nov., but ASE is so far posterior that it is level with ML, and thus the genus diagnosis is modified accordingly. Other differences and similarities among Caeculisoma and related genera with three pairs of scutalae in larval Callidosomatinae are also compared in Table 1.

The position of the ML scutulae may cause us to reclassify the monotypic genus Iguatonia Haitlinger, 2004 as a species of Caeculisoma . However, in this genus the position of the scutal setae are unusual, with all three pairs of scutulae in the anterior half of the scutum and ASE very close to PSE. Nevertheless, a broader study of the Callidosomatinae is required to assess generic boundaries as, based on our study, the position of scutal setae may be graded so finely between species that genera are no longer easily defined.