Hyracarus minimus Stekolnikov, 2025

Hyracarus minimus Stekolnikov , sp. nov.

( Figs. 1D, E View FIGURE 1 , 5 View FIGURE 5 , 6 View FIGURE 6 )

Diagnosis. SIF = 5B-B-3-2111.3321; fPp = B/B/BBB; fD = [(4–6)-(6–8)]-(8–9)-(8–9)-(8–10)+(11–19), DS = 48– 60, V = 38–45, Hv = 2(0), NDV = 88–104; Ip = 679–722; scutum pentagonal, with angulate posterior margin; nasus expanded in medial part, with rounded end; sensillary bases slightly anterior to level of PLs (PSB–P-PL from 1 to 4, mean 1); PL> AL ≥ AM; sensilla nude; cheliceral blade with dorsal tooth and row of ca. 12 ventral denticles; parasubterminala ( z) nude or ciliated. Unspecialized setae (leg I, II, III): femur 6, 6, 5; tibia 9, 6, 6; tarsus 24, 17, 17. Measurements are given in Table 2 View TABLE 2 .

Description of larva. IDIOSOMA ( Figs. 1D, E View FIGURE 1 , 5A–D, H, I View FIGURE 5 ). Eyes 2 + 2, on ocular plate; 48–60 barbed dorsal idiosomal setae; distribution by anterior rows—10–13 C, 8–9 D, 8–9 E, 8–10 F, 1 st row double, two marginal setae of 2 nd row shifted anteriad, marginal setae of 1 st and 2 nd rows (humeral setae) longest; two sternal setae between coxae III; 38–45 ventral setae; 2 humeroventral setae between coxae II and III laterally in holotype and three paratypes, absent in two paratypes; NDV = 118–140; reduced stigmata visible between gnathocoxa and coxae I, tracheae absent.

GNATHOSOMA ( Fig. 5E–G View FIGURE 5 ). Cheliceral blade with one dorsal tooth and ventrolateral row of ca. 12 denticles; cheliceral base with small dense puncta in proximal part; gnathobase (infracapitulum) with small sparse puncta, bears one pair of branched tritorostral setae; galeal (deutorostral) seta ciliated; palpal claw (odontus) with three prongs; palpal femoral, genual, and tibial setae branched; palpal tarsus with five unspecialized setae (dorsal seta bears very small, poorly visible cilia) and tarsala ( ω).

SCUTUM ( Figs. 1D View FIGURE 1 , 5A View FIGURE 5 ). With small dense puncta, pentagonal, with angulate posterior margin; nasus expanded in medial part, with rounded end; AM situated slightly posterior to level of ALs, sensillary (trichobothrial) bases slightly anterior to level of PLs (PSB–P-PL from 1 to 4, mean 1); PL> AL ≥ AM; all scutal setae barbed similarly to dorsal idiosomal setae; sensilla (trichobothria) flagelliform, nude.

LEGS ( Fig. 6 View FIGURE 6 ). All six-segmented (with undivided femur), with one pair of claws and claw-like empodium, onychotriches absent. Sensory setae: Leg I: 2 genualae ( σ), microgenuala ( κ), 2 tibialae ( φ) in tandem, microtibiala ( κ) near distal tibiala, tarsala ( ω), famulus ( ε) distal to tarsala, subterminala ( ζ), nude or ciliated parasubterminala ( z), pretarsala ( ζ). Leg II: genuala ( σ), microgenuala ( κ) distal to genuala, 2 tibialae ( φ) in tandem, tarsala ( ω), famulus ( ε) behind tarsala, pretarsala ( ζ). Leg III: genuala ( σ), tibiala ( φ). Unspecialized setae (leg I, II, III): coxa 2, 1, 1; trochanter 1, 1, 1; femur 6, 6, 5; genu 4, 4, 4; tibia 9, 6, 6 or 8, 6, 6 (variation recorded); tarsus 24, 17, 17. Ventral setae feathered, dorsal setae branched or nude. Numbers of nude setae: Leg I: tarsus 6, tibia 4, genu 1; Leg II: tarsus 1, tibia 1, genu 1; Leg III: tarsus 3, tibia 3, genu 2, femur 1.

Type material. Holotype: larva ( ZIN 18402 View Materials ), ex Micaelamys namaquensis (No. ObMn12), South Africa, Western Cape, Ouberg Private Nature Reserve , near Montagu, Succulent Karoo , 6 November 2023, coll. Alyssa Little. Paratypes: three larvae ( ZIN 18398 View Materials , 18399 View Materials , and 18411) ex M. namaquensis (Nos ObMn04 and ObMn12), same locality, date, and collector ; one larva ( ZIN 18447 View Materials ) ex M. namaquensis (No. WbMn15), South Africa, Western Cape, Witteberg Private Nature Reserve , between Matjesfontein and Laingsburg, Fynbos , 11 December 2023, coll. Alyssa Little ; one larva ( ZIN 18486 View Materials ) ex Rhabdomys pumilio (No. ObRp4), Western Cape, Ouberg Private Nature Reserve , near Montagu, Succulent Karoo , 7 November 2023, coll. Lola Singo.

Etymology. The specific epithet refers to the size of the new species, smaller than that of the sympatric species H. maximus sp. nov.

Differential diagnosis. Hyracarus minimus sp. nov. is the only species of Hyracarus in which the humeroventral setae are present in a part of specimens, but absent in another part. Using the key to species of Hyracarus (Stekolnikov et al. 2025) , the specimens with two humeroventral setae could be determined as H. aryanicki Stekolnikov, Halajian and Matthee, 2025 . However, the new species differs from H. aryanicki by the presence of the following features: 5 unspecialized setae on palpal tarsus vs. 7; 24 unspecialized setae on tarsus I vs. 25; a higher number of nude setae on legs (for example, Leg III: tarsus 3, tibia 3, genu 2, femur 1, vs. tarsus 1, tibia 1, genu 1); much more numerous scutal puncta; absence of puncta on palpal femur; and shorter legs (Ip = 679–722 vs. 880–905).

The specimens without humeroventral setae is similar to H. bethuliensis Stekolnikov, Halajian and Matthee, 2025 , but the new species differs from H. bethuliensis by the presence of branched ventral palpal tibial seta vs. nude (fPp = B/B/BBB vs. B/B/BBN); sensillary bases anterior to level of PLs vs. posterior by 2–5 µm; posterior scutal margin not pointed; absence of puncta on palpal femur; and by slightly shorter legs (Ip = 679–722 vs. 763–792).