Osperalycus tenerphagus Bolton, Klompen, Bauchan & Ochoa, 2014, gen. nov., sp. nov.
Creators: name: Bolton, Samuel J.
name: Klompen, Hans
name: Bauchan, Gary R.
name: Ochoa, Ronald
Publisher: name: Zenodo
Year: 2014
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Arachnida
Acariformes
Nematalycidae
Osperalycus
Osperalycus tenerphagus

description: Osperalycus tenerphagus Bolton and Klompen gen. nov., sp. nov.
Figures 1–8
Diagnosis
Osperalycus is readily distinguished from other genera of Nematalycidae by the presence of simple setae of similar size along the opisthosoma (Figure 1A, B); the simple setae next to the anal opening of Gordialycus and Nematalycus are at least three times as long as those along the rest of the opisthosoma, although the opisthosoma of Gordialycus and Nematalycus is often almost completely nude. Cunliffea and Psammolycus have bifurcate or trifurcate setae along the opisthosoma. Osperalycus is also readily distinguished from Gordialycus and Nematalycus by the baculiform solenidion on tarsus II – this solenidion has a distinctly swollen or bulbous tip in Gordialycus and Nematalycus. The most distinct characters of Osperalycus are to be found in the mouthparts (Figure 2A, B). The vessel (Ve) – modified from the lateral lips – is a very unusual structure that appears to be unique to this genus (Figure 2A). Markedly short chelicerae (Ch) (<15 µm) are found in both Osperalycus tenerphagus and Psammolycus delamarei, but not Nearctic cf. Psammolycus or any other genus of Nematalycidae. Osperalycus is also distinct from all other genera in having rutella (Ru) that overlap at the midline (Figure 2A).
Female
General morphology. Idiosoma ≈ 600 µm long (≈12 times longer than wide) when fully extended (Figure 1A, B). Cuticle with flat round projections, or palettes, sensu Haupt and Coineau (1999), lining the latitudinal annuli (Figure 3A–D). Trachea and peritremes absent. Lyrifissures absent from idiosoma. Podocephalic canals terminating anteriorly between the bases of the chelicerae; extending back beyond coxae I. Distinct glands leading into podocephalic canals at coxae I. Long narrow oesophagus extends to proximity of metapodosoma.
Prodorsum. Trichobothria absent; naso absent; eyes absent. Three pairs of setae (exa, in and le) and one unpaired rostral (ro) seta. All setae simple and close to the midline of the prodorsum (Figure 2A). Setae ro, le and in subequal and short (4–8); exa long (16–22).
Opisthosoma. All setae simple. Setae associated with all nine opisthonotal segments: c1–4, d1–2, e1–2, f1–3, h1–2, ps1–3, ad1–3, an1–3, pa1–3. Frequent and noticeable asymmetry in the longitudinal positions of pairs of setae (Figure 1A, B). In segmental remnants F-PA, ancestrally dorsolateral setae are displaced to a ventrolateral or ventral position that is usually noticeably more anterior than the dorsomedial setae of the same segment. Segment C very long; position of c2 and c3 much more posterior than c1 and c4.
Setae on segments C–E generally shorter (5–15) than those on segments F-PA (10–19). Setae c2 short (5–8); proximal setae c3 comparatively long (9–13). Longest opisthosomal setae h2 and ps3 (15–19). From segments H to PA, ventral setae (h2, ps3, ad3, an3, pa3) typically 1 to 4 µm longer than lateral and dorsal setae on the same segment; lateral and dorsal setae subequal.
Distinct anal valves projecting from the anus (Figure 4A–C). Ventral furrow, in which annular ridges terminate (Figure 4D), extending from proximity of anal valves to genital region (Figure 4A).
Three pairs of genital (g) setae and two pairs of aggenital (ag) setae (Figure 1C). Genital and aggenital setae short (3–7) compared with most other opisthosomal setae. Two pairs of bilobed genital papillae (Figure 1D).
Podosoma. Large gap separating legs II and III (Figure 1B). Coxal fields I and II medially separated by intercoxal region (Figure 2B). Single pair of intercoxal setae (between coxal fields II). Coxal fields III and IV medially fused (Figure 1C). Each coxal field I with one bifurcate seta and one simple seta; each coxal field II with one bifurcate seta; coxal fields III with one bifurcate seta and two simple setae on each side of the fused coxal plate; coxal fields IV with one simple seta on each side of the fused coxal plate.
Legs. Pretarsi I–IV each with two lateral claws and a ciliated empodium (Figure 5A–E). Solenidial formulae femora–tarsi for individual legs I–IV: 0-1-2-1; 0-0-0-1; 0-0-0-0; 0-0-0- 0. Longitudinal grooves of shortest solenidion phi (φ) (tibia I) restricted to bulbous tip (Figure 5F). Other solenidia baculiform with longitudinal grooves extending almost all the way to the base. Solenidia omega (ω) on tarsi I and II subequal and noticeably larger than solenidion phi (φ) and sigma (σ) on, respectively, tibia I and genu I (Figure 6).
Setae absent from trochanters I–IV. Setal formulae femora–tarsi for individual legs I–IV (excluding solenidia and famuli): 4-6-7-16; 2-2-2-9; 1-0-2-6; 1-0-2-5. All setae on femora–tibiae I–IV simple. Tarsi I–IV with various setae (see below). Femur I sometimes lacking the dorsal seta normally added in post-protonymphal instars – some individuals with three setae on one femur I and four on the other.
Tarsus I (Figure 5A). Seven pairs of setae (p, tc, ft, u, a, pv and pl) and two unpaired setae (s and d). Proral (p) setae conical and extending from turbercle. One tectal (tc ″) and one fastigial (ft ″) seta usually semi-bifurcate, with one branch short and barb-like – sometimes short and basal enough for the seta to qualify as simple (see aforementioned criteria in Material and methods section), or rarely long enough to be bifurcate. Other fastigial (ft') seta usually bifurcate, rarely semi-trifurcate or trifurcate. All other setae simple. Subunguinal (s) seta centred between pair of anterolateral (a) setae. Dorsal (d) seta proximal and posterior to base of solenidion ω. Small stubby famulus (ε) near tc ″. Dorsolateral lyrifissure next to posterior margin of tarsus (obscured by overlying integument when viewed under LT-SEM).
Tarsus II (Figure 5B, C). Four pairs of setae (p, tc, ft and u) and one unpaired seta (d). Setae p, tc and u bifurcate and projecting forward past base of ambulacrum; ft simple; d trifurcate. Long rod-like famulus near tc ″. Base of solenidion ω next to posterior margin of tarsus.
Tarsus III (Figure 5D). Two pairs of setae (p and u) and two unpaired setae (tc ″ and d). Setae p, u and tc ″ bifurcate and projecting forward past base of ambulacrum; d bifurcate.
Tarsus IV (Figure 5E). Identical to tarsus III but with tc ″ absent.
Gnathosoma. Gnathosoma including a vessel (Ve) – modified from the lateral lips – into which the chelae (opposing digits) slot (Figure 2A). Chelicerae (Ch) ≈ 12 µm long and slanting downwards, anteriorly, into the vessel. Single dorsal seta on each chelicera. Rutella (Ru) consisting of a swollen base with a narrow extending digit. The rutella lie against the anterior surface of the vessel and overlap at the midline, appearing as an inverted v – more discernible, under a light microscope, when the chelae are not within the vessel. Palps (Pa) ≈ 10 µm long and three-segmented, tentatively designated femur, genu and tarsus; solenidia absent; setal formula femur–tarsus for each palp: 0-1-6; distal tarsal seta with cupshaped tip; all other setae simple. Palp tarsus also with three very small cuticular protuberances (only visible under LT-SEM and omitted from Figure 2A, B). Subcapitulum with four pairs of setae: m, a, or1–2 (Figure 2B). Adoral setae (or1–2) typically unevenly tapering (or2 sometimes evenly tapering); anterior pair (or1) vestigial and broad.
Ontogeny
Idiosoma and appendages. From larva to adult, the idiosoma increases greatly in length compared with the appendages (Table 1; Figures 7, 8A, B). Notably, there is no apparent increase in the length of the palp.
Chaetotaxy. Aside from the legs and coxal fields (see below), setal additions only occur in the genital region and segments AD to PA (Table 2). Adults readily distinguished from tritonymphs by the presence of setae ag2 (very posterior and close to f3) and long pa1–3 (Table 2).
New segmental additions of setae to the posterior tip of the opisthosoma always short (3–7), increasing two- to four-fold in length at the next instar (Table 2). Several other opisthosomal setae noticeably increase in length from the larval to adult instar (Figures 1A, B, 7): seta f3 increases approximately four-fold (from 3–4) to be subequal to f2 and f1 (11–16); setae d2 and e2 increase by about 50% (from 7–10 to 10– 15). All other opisthosomal and prodorsal setae increase only slightly (<30%) or not at all.
Leg setation complete (including coxal fields) by the deutonymphal instar (Table 3). Setation of tarsus I is completed by the addition of an unpaired dorsal (d) seta in the protonymph. Chaetotaxy unchanging for tarsi II–IV. Numbers of solenidia, famuli and lyrifissures also unchanging for all leg segments. Gnathosoma without additions of setae or any other structures.
Material examined
Holotype female (OSAL 015134), USA, Ohio, Franklin Co., Kinnear Road, 39.9990 N, 83.0468 W, silty clay loam from suburban prairie (including shrubs, grasses and small trees); collector: Samuel Bolton, May 2011, 40 cm deep (SB11- 05-I). Same data: 9 F (OSAL 0103239, 0105137, 0105138, 0105147, 0105148, 0105149, 0105153, 0105155, 0105156), 1 TN/F? (OSAL 0105135), 5 TN (OSAL 0105143, 0105146, 0105151, 0105152, 0105157), 1 DN (OSAL 0105145), 1 PN (OSAL 0105150), 3 L (OSAL 0103237, 0105141, 0105142), 1 pharate (TN–F, OSAL 0105154). Same locality and collector, July 2010, 60 cm deep (SB10-0724-I): 4 F (OSAL 0103240, 0105136, 0105139, 0105140), 1 DN, (OSAL 0105144), 2 PN (OSAL 0103241, 0103242), 1 L (OSAL 0103245), 2 pharates (L-PN, OSAL 0103243, 0103244). August 2011 (LT-SEM material), 60 cm deep: 9 F, 1 TN/F?, 6 TN, 1 DN/ TN?, 1 DN, 1 PN (used for SEM, not recovered). USA, Ohio, Ashtabula Co., West Main Road, 41.9246 N, 80.6138 W, sandy loam in small chestnut plantation, collector: Samuel Bolton, July 2011, 40 cm deep (SB11-07- IV): 1 F (OSAL 0105133), 1 TN (OSAL 0103238), 1 DN (OSAL 0105132).
Note: Measurements taken from slide-mounted specimens rather than scanning electron microscopy, for which the integument is generally not fully extended.
Notes (Key): Unbracketed: simple seta; bracketed: bifurcate; bracketed and underscored: semibifurcate; double bracketed: trifurcate; angle bracketed: conical; hyphen: absence of setae; n/a: leg absent; highlighted grey: seta added in this instar.
Type material and depositor
Holotype female (OSAL 0105134) at Ohio State University Acarology Collection (OSAL), Columbus, Ohio, USA. Paratypes: US National Collection (USNM), housed at the Beltsville Agricultural Research Center, USDA, Beltsville, MD, USA: 2 F (OSAL 0105137, 0105147); Natural History Museum (BMNH), London, UK: 2 F (OSAL 0105140, 0105148); all other paratypes at OSAL.
Etymology
Binomial. Osperalycus tenerphagus. Ospera - is a combination of the Latin terms for “mouth” (os) and “purse/bag” (pera) in reference to the soft and unsclerotized vessel of the gnathosoma; - lycus is a Latinized Greek ending given to three of the four other genera of Nematalycidae. The species name, tenerphagus, combines the Latin term for “tender” with the Greek-derived Latin suffix for “feeding”, referring to the delicate mechanism hypothesized to explain how this mite may carefully pick up small micro-organisms and place them into its feeding vessel without rupturing them (Bolton et al. in preparation).
Systematic relationships
Whereas rutella were thought to be absent from the Nematalycidae (Walter 2009), they are clearly present in Osperalycus tenerphagus. Rutella also appear to be present in Gordialycus sp. nov. and cf. Psammolycus sp. nov. (pers. obs.). The presence of rutella combined with the absence of a tracheal system more firmly places the Nematalycidae within the Endeostigmata. Other newly observed characters also suggest a closer relationship with the Endeostigmata than the Tydeoidea, e.g. presence of setae for all nine opisthosomal segments and more than two pairs of setae on the C and F segments.
Key to the genera of the Nematalycidae
1. Opisthosomal setae near the anal opening at least three times as long as those along the rest of the opisthosoma, which is often almost completely nude; chelicerae long (> 15 µm). ........................................................................... 2 Setae along the length of the opisthosoma of similar size; chelicerae can be short (<15 µm) or long (> 20 µm). .............................................................. 3
2. Legs III and IV noticeably smaller than leg II; body usually extremely elongated (adult length>20× width). ......................................... Gordialycus Legs III and IV not noticeably smaller than leg II; body not extremely elongated (adult length <20× width). ....................................... Nematalycus
3. Palps with two segments; pretarsi II to IV without claws; tritonymphs and adults with three pairs of simple genital papillae; chelicerae long (> 20 µm) but with very short chelae (opposing digits); opisthosomal setae always trifurcate. ........................................................................................ Cunliffea Palps with three or four segments; lateral claws present on pretarsi II to IV; tritonymphs and adults with two pairs of bilobed genital papillae; if chelicerae long (> 20 µm), chelae distinctly elongated; opisthosomal setae trifurcate, bifurcate or simple. ............................................................................ 4
4. Palps with four segments; opisthosomal setae distinctly bifurcate or trifurcate; rutella absent or never overlapping at the midline when present; if chelicerae long (> 20 µm), chelae distinctly elongated. ........... Psammolycus Palps with three segments; opisthosomal setae long and simple (with very small basal barbs that are not visible under a light microscope); rutella overlap at the midline; chelicerae short (<15 µm). .................... Osperalycus
description: Published as part of Bolton, Samuel J., Klompen, Hans, Bauchan, Gary R. & Ochoa, Ronald, 2014, A new genus and species of Nematalycidae (Acari: Endeostigmata), pp. 1359-1373 in Journal of Natural History (J. Nat. Hist.) (J. Nat. Hist.) 48 (23 - 24) on pages 1361-1372, DOI: 10.1080/00222933.2013.859318, http://zenodo.org/record/4631362