Ptilonyssus holmhanseni, Haarder & Dimov, 2025

Ptilonyssus holmhanseni sp. nov.

http://zoobank.org/ urn:lsid:zoobank.org:act:D4FED965-35BA-4004-BE99-58D63BF5D625

Type material

Female holotype ( RASP 8) from Parus major Linnaeus, 1758 ( Passeriformes : Paridae ), Denmark, Lejre, near train station (55° 36' 12.0" N, 11° 58' 19.0" E), 12 April 2023, bird collected by Lars Holm Hansen.

Description (Female)

Measurements – LB – 468; WID – 194; LPS – 176; WPS – 144; LOS – 178; WOS – 112; LSS – 83; WSS – 72; LGS – 64; WGS – 72; LAS – 72; WAS – 43; LG – 82; WG – 41; LCH – 63; WCH – 9; Lleg I –228; Lleg II – 179; LlegIII – 184; Lleg IV –225.

Dorsum ( Fig. 1 View Figures 1–2 ) – Podosomal shield (PS) occupies most of the podosomal area. Anterior part of the shield is gradually narrowed to the anterior end, posterior margin straight. Surface of this shield with 8 pairs of setae (j2-6, z2-5), [in holotype left seta z5 absent]. Soft dorsal surface of podosoma with four pairs of mesolateral setae (r5, r6, s5, s6). Soft dorsal surface of opisthosoma with 6 pairs of setae (Z1-4, R1-2). Opisthosomal shield (OS) roughly oval-shaped, with wide shallow concavity on anterior margin; surface of this shield with 3 pairs of setae (J1, J2, J4). Stigmata (Stg) with peritremes located dorsolaterally at level of coxae III.

Venter ( Fig. 2 View Figures 1–2 ) – Sternal shield (SS) large, with oval shape, 3 pairs of sternal setae located on its surface (St1-3), sternal formula (St1<St2 = St3). Genital shield (GS) large, surface with 1 pair of short genital setae (he4). Soft cuticle of opisthosoma with 10 setae (Jv1, 2, 4, Zv1). Anal shield oval, its surface with 2 longer preanal setae are located laterally to anus (An) and 1 short postanal posterior to it, anal formula (Ad> PA). Aspero (Asp) present.

Gnathosoma – Gnathosomal formula 2-0-2. Setae hyp2 and hyp3 are absent. Five deutosternal denticles (Dd) arranged in longitudinal row.

Legs: All legs six-segmented. Formula of coxal setae 2-2-2-1.

Tarsal receptor complex ( Fig. 3a View Figure 3 ) – Two chemo-mechanoreceptor sensilla with apical pore (up), four olfactory porous single-cavity sensilla (sw), and seven chemoreceptor sensilla with peripheral cavities (dw).

Palpal receptor complex ( Fig. 3b View Figure 3 ) – Five (three large and two small) tactile sensilla, three pair of little tactile sensilla with apical pore (np), three double-walled with apical pore sensilla (dw-up), and two single-walled with apical pore sensilla (sw-up). These minute setal structures were examined and recognized with a light microscope.

Male, larva, and nymph unknown.

Differential diagnosis

Ptilonyssus holmhanseni sp. nov. is most similar to the widespread Holarctic species Ptilonyssus pari Fain & Hyland, 1963 . The differential characters between the species are given in Table 1. In short, P. holmhanseni sp. nov. supports fewer setae on the opisthosomal shield and ventral opisthosoma when compared to P. pari . The opisthosomal shield of P. holmhanseni sp. nov. is roughly ovate (with narrow posterior end in P. pari ) and the anterior margin is concave (straight in P. pari ). Further important differences are found in the shape of the posterior margin of the podosomal shield as well as the general shape of the sternal shield. More discrete differences are observed in the gnathosomal and sternal formula, and tarsal receptor complex.

Etymology

The new species is named after Lars Holm Hansen, the eminent Danish naturalist, who has contributed immensely to the on-going study of the Danish avian mite fauna.