Heatherella osleri, Seeman & Minor & Baker & Walter, 2018

Seeman, Owen D., Minor, Maria, Baker, Michelle R. & Walter, David Evans, 2018, A revision of the Heatherellidae (Parasitiformes: Mesostigmata) with a new genus and two new species from Australasia, Zootaxa 4434 (3), pp. 441-465 : 444-450

Heatherella osleri n. sp. Seeman, Minor, Baker & Walter

( Figs 1–14 , 36 )

Diagnosis: With the characteristics of the genus. Adult: sternal shield (bearing st2) subhexagonal, without endopodal elements, poorly differentiated anteriorly; ventral setae all short, bulbous and barbed; dorsal and marginal setae with ciliate crests; dorsal shield heavily ornamented; idiosomal margin with ten pairs of idiosomatic protuberances (protuberances P - s4 and P -s6 present), distinct pustule associated with seta s5 absent, P -s5 similar to other protuberances; dorsum with seta z2; seta z6 anterior to s6, seta Z1 anterior to S1, seta z5 placed obliquely to seta j5; marginal r -R series setae not duplicated, 25–28 setae on each side, sometimes asymmetrical. Female: female with st 3 in soft cuticle and st4 on small shields. Male: seta av1 on genu II a blunt spur.

Idiosomal dimensions: Females (n= 3) 360–375 long x 255–265 wide (holotype 360 x 265, small lateral split on one side); males (n= 9) 345–370 long x 220–255 wide.

Female. Venter ( Fig. 1 ). Tritosternum bifurcate; sternal region with a pair of small presternal platelets; st 1 in plicate cuticle, st2 on subhexagonal, lineate-microtuberculate shield with pair of large pores in posterior corners; st 3 in soft cuticle; st4 on small, subtriangular shields; all sternal setae short (st1 4–7, st 2 9–10, st3 9, st4 8–9). Genital shield broadly subtriangular, flaring posteriorly, rounded anteriorly, irregularly reticulate with short (8–9), simple st5; shield length 84–86, maximum width 90–98. Opisthogaster ( Fig. 1 ) with seven pairs of short (7–14) setae (JV1–2, JV4, ZV1–4), bulbous basally, tapering to fine point and ciliate on one side, lengthening posteriorly; two pairs of gland openings with raised rims posterolaterad coxae IV; one pair laterad para-anal setae; one pair laterad ZV1; one pair anteriad ZV4. Setae JV5 caudal, posterior to final R seta and beneath most posterior spout. Anal region raised, with pair short (~5) simple setae on anterior corners anal opening (JV3) and para-anal and postanal setae similar to ventral setae. Peritrematal shield obsolete, lateral region spiculate-microtuberculate, microtubercles becoming subreticulate across anterior ventral region and evanescent posteriorly; peritremes absent, stigma in raised tuberculate process ( Fig. 36 ).

Dorsum ( Fig. 2 ). Dorsal shields comprising single median podonotal-mesonotal shield, latinotal shields, eight pre-pygidial platelets (often concealed), three pygidial shields (one medial, two lateral), all surrounded by dorsomarginal portion of opisthogastric-peritrematal-marginal shield; anteriorly, podonotal shield extending ventrally and fused with marginal shield. Median dorsal shield irregularly areolate, bearing eight pairs of setae (j4–6, J1–4, z5; not including setae on vertex, i.e., ventrally placed j1, z1 and dorsally placed j2–3, z2, s1); latinotal shields fused with podonotal shield anteriorly, each with four pairs of setae (z6, Z1–4); pre-pygidial platelets nude; median pygidial shield with two setae (J5), lateral pygidial shield each with one seta (Z4). All dorsal and marginal setae thickened, barbed, with ciliate crests, setal length 17–23. Seta z6 anterior to s6, seta Z1 anterior to S1, seta z5 placed obliquely to seta j5. Dorsal margin of shield bearing ten pairs of gland-bearing protuberances mostly aligned with s -S series setae (s1, s2, s4–6, S1–5) but also j2, z2–4; protuberance P -s5 not pustule-like, similar in form to other protuberances ( Table 1). Marginal setae (r -R series) hypertrichous, with 25–28 setae on each side (sometimes asymmetrical).

Gnathosoma ( Figs 3–7 ). Subcapitulum with strong row of denticles between palpcoxal setae; and three shorter, less distinct rows between setae h3 and posterior to palpcoxal setae; all but most posterior row extend across deutosternum as fine denticles; deutosternal gutter narrow, with two additional rows of fine denticles anterior to palpcoxal setae; all subcapitular setae simple, acuminate, length h 1 11–12, h 2 9–10, h 3 11–12, pc 8–10 (h3 expressed asymmetrically in holotype); corniculi simple. Chelicerae (~75 long), second article (55–65 long) with 3 subdistal teeth around pilus dentilis, deep notch receives fixed digit; moveable digit (25–28) tridentate; cheliceral seta (~12 long) thick, somewhat flattened, acuminate, inserted on paraxial side of chelicera. Tectum coarsely denticulate, with median prong (sometimes bifid) and 2–3 pairs of lateral teeth.

Legs ( Figs 8–11 ). Leg setae generally unmodified; dorsal femoral setae on leg I barbed ( Fig. 8 ); femoral and genual setae subequal in length.

Male. Similar to female except as follows. Venter ( Fig. 12 ). Shield bearing st2–4 and subcircular genital opening covered by a pair of platelets; st5 on ventral, subtriangular extension of opisthogastric-peritrematalmarginal shield (and so eight pairs of ventral setae appearing to be present). Dorsum ( Fig. 13 ). Dorsally with podonotal and mesonotal shields; podonotal shield fused with lateral shields, bearing five pairs of setae (j4–6, z5– 6) excluding setae at vertex (j1–3, z1–3, s1); mesonotal shield mostly free from lateral mesonotal shields (fused anteriorly), mesonotal shield bearing four pairs of setae (J1–4), lateral mesonotal shields bearing three pairs of setae (Z1–3); eight pre-pygidial platelets and pygidial shields as in female; protuberances and s -S and r -R setae as in female. Gnathosoma ( Figs 5, 7 ). Similar to female; teeth on gnathotectum less developed. Legs ( Fig. 14 ). Leg II with setae av1 on femur and genu a blunt spur (8– 9 x 5 wide, 5– 6 x 2–3 wide, respectively).

Material examined. Holotype female, 2 female, 9 male paratypes, Australia, New South Wales, Lansdowne State Forest, 31°45′S 152°37′E, Graham Osler, 22 February 1996, Tullgren extraction of top 5 cm of soil in mixed hardwood forest with Eucalyptus pilularis & E. propinqua . Holotype, 1 female and 7 male paratypes deposited in QM; 1 female (ANIC 51-006365), 1 male paratype deposited in ANIC (ANIC 51-006366); 1 male paratype deposited in each of CNC and NZAC (NZAC02016473).

Etymology: The new species is named in honour of the young acarologist who collected these specimens many years ago, Graham Osler.

Comments. This species is found in wet sclerophyll forests; more details on the mite’s ecology may be found in Osler & Beattie (2001). This species is obviously different from the two species from Queensland in having the dorsal setae with ciliate crests (simple setae in other Heatherella ), seta z2 present (absent in other Heatherellidae ), and ten pairs of lateral protuberances (8–9 pairs in other Heatherella including P -s5; see Table 1). Heatherella osleri seems more closely related to H. callimaulos in sharing the position of the dorsal setae (i.e. seta z6 anterior to s6, seta Z1 anterior to S1, seta z5 placed obliquely to seta j5), having marginal protuberance P -s4 present and having males with seta av1 on genu II modified into a spur-like process.

The presence of ten pairs of protuberances, the maximum number known so far in Heatherellidae , suggests a trend towards an increase in protuberance number. The presence of protuberance P -s 4 may be a synapomorphy, but protuberance P -s5 is an autapomorphy, and we interpret protuberance P -s6 as a homoplasy as it is present only in H. osleri and the new genus described below ( Table 1).

Figures

FIGURE 1. Heatherella osleri n. sp. female holotype, venter.

FIGURE 2. Heatherella osleri n. sp. female holotype, dorsum.

FIGURES 3–8. Heatherella osleri n. sp. (3) female, ventral gnathosoma (seta h3 eXpressed asymmetrically in holotype); (4) female, gnathotectum; (5) male, gnathotectum; (6) female, chelicera; (7) male, chelicera; (8) female, leg I.

FIGURES 9–11. Heatherella osleri n. sp. female holotype, posterior views: (9) leg II; (10) leg III; (11) leg IV.

FIGURES 12–14. Heatherella osleri n. sp. male (12) venter; (13) dorsum (marginal shields not shown laterally; torn anteriorly from marginal shield); (14) leg II, anterior view.

FIGURES 34–37. (34) Heatherella acanthocharis walter, 1997, dorsomarginal protuberances, pustules and pores of paratype female (P-s5 pustule; P-s6 pore; P-S1 protuberance), dorsal view of flattened specimen, right side; (35) Aheatherella mira n. sp., dorsomarginal protuberances, pustules and pores of paratype female (P-s5 pustule; P-s6 protuberance with closely associated seta), dorsal view of ventrolateral fragment with broken r-setae, left side; (36) Heatherella osleri n. sp., peritreme of paratype female (ventral view, right peritreme of mite); (37) Aheatherella mira n. sp. peritreme of paratype female (ventral view, left peritreme of mite; sclerotised eXopodal portion of eXopodal-peritrematal shield shaded).