Osperalycus tenerphagus, Bolton & Klompen & Bauchan & Ochoa, 2014

Bolton, Samuel J., Klompen, Hans, Bauchan, Gary R. & Ochoa, Ronald, 2014, A new genus and species of Nematalycidae (Acari: Endeostigmata), Journal of Natural History (J. Nat. Hist.) 48 (23 - 24), pp. 1359-1373: 1361-1372

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http://doi.org/ 10.1080/00222933.2013.859318

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scientific name

Osperalycus tenerphagus

gen. nov., sp. nov.

Osperalycus tenerphagus   Bolton and Klompen gen. nov., sp. nov.

Figures 1–8 View Figure 1 View Figure 2 View Figure 3 View Figure 4 View Figure 5 View Figure 6 View Figure 7 View Figure 8


Osperalycus   is readily distinguished from other genera of Nematalycidae   by the presence of simple setae of similar size along the opisthosoma ( Figure 1A, B View Figure 1 ); 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 View Figure 2 ). The vessel (Ve) – modified from the lateral lips – is a very unusual structure that appears to be unique to this genus ( Figure 2A View Figure 2 ). 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 View Figure 2 ).


General morphology. Idiosoma ≈ 600 µm long (≈12 times longer than wide) when fully extended ( Figure 1A, B View Figure 1 ). Cuticle with flat round projections, or palettes, sensu Haupt and Coineau (1999), lining the latitudinal annuli ( Figure 3A–D View Figure 3 ). 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 View Figure 2 ). 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 View Figure 1 ). 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 View Figure 4 ). Ventral furrow, in which annular ridges terminate ( Figure 4D View Figure 4 ), extending from proximity of anal valves to genital region ( Figure 4A View Figure 4 ).

Three pairs of genital (g) setae and two pairs of aggenital (ag) setae ( Figure 1C View Figure 1 ). Genital and aggenital setae short (3–7) compared with most other opisthosomal setae. Two pairs of bilobed genital papillae ( Figure 1D View Figure 1 ).

Podosoma. Large gap separating legs II and III ( Figure 1B View Figure 1 ). Coxal fields I and II medially separated by intercoxal region ( Figure 2B View Figure 2 ). Single pair of intercoxal setae (between coxal fields II). Coxal fields III and IV medially fused ( Figure 1C View Figure 1 ). 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 View Figure 5 ). 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 View Figure 5 ). 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 View 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 View Figure 5 ). 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 View Figure 5 ). 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 View Figure 5 ). 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 View Figure 5 ). 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 View Figure 2 ). 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 View Figure 2 ). Subcapitulum with four pairs of setae: m, a, or1–2 ( Figure 2B View Figure 2 ). Adoral setae (or1–2) typically unevenly tapering (or2 sometimes evenly tapering); anterior pair (or1) vestigial and broad.


Idiosoma and appendages. From larva to adult, the idiosoma increases greatly in length compared with the appendages ( Table 1 View Table 1 ; Figures 7 View Figure 7 , 8A, B View Figure 8 ). 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 View 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 View 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 View Table 2 ). Several other opisthosomal setae noticeably increase in length from the larval to adult instar ( Figures 1A, B View Figure 1 , 7 View Figure 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 View 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 View Materials ), 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 View Materials , 0105137 View Materials , 0105138 View Materials , 0105147 View Materials , 0105148 View Materials , 0105149 View Materials , 0105153 View Materials , 0105155 View Materials , 0105156 View Materials ), 1 TN/F? ( OSAL 0105135 View Materials ), 5 TN ( OSAL 0105143 View Materials , 0105146 View Materials , 0105151 View Materials , 0105152 View Materials , 0105157 View Materials ), 1 DN ( OSAL 0105145 View Materials ), 1 PN GoogleMaps   ( OSAL 0105150), 3 L ( OSAL 0103237 View Materials , 0105141 View Materials , 0105142 View Materials )   , 1 pharate (TN–F, OSAL 0105154 View Materials )   . Same locality and collector, July 2010, 60 cm deep (SB10-0724-I): 4 F ( OSAL 0103240 View Materials , 0105136 View Materials , 0105139 View Materials , 0105140 View Materials )   , 1 DN, ( OSAL 0105144 View Materials )   , 2 PN ( OSAL 0103241 View Materials , 0103242 View Materials )   , 1 L ( OSAL 0103245 View Materials )   , 2 pharates ( L-PN, OSAL 0103243 View Materials , 0103244 View Materials )   . 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) GoogleMaps   : 1 F ( OSAL 0105133 View Materials )   , 1 TN ( OSAL 0103238 View Materials )   , 1 DN ( OSAL 0105132 View Materials )   .

Type material and depositor

Holotype female ( OSAL 0105134 View Materials ) 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 View Materials , 0105147 View Materials ); Natural History Museum ( BMNH), London, UK: 2 F ( OSAL 0105140 View Materials , 0105148 View Materials ); all other paratypes at   OSAL.


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  

Table 3. Osperalycus tenerphagus sp. nov. Setal addition pattern for legs (including coxal fields) across instars.

Tarsus I Tibia I Genu I Femur I Trochanter I Coxal field I 10 (1) (2) ‹2› 6 4 2 - 1 11 (1) (2) ‹2› 6 6 3 - 1 (1) 11 (1) (2) ‹2› 7 6 4 - 1 (1) 11 (1) (2) ‹2› 7 6 4 - 1 (1) 11 (1) (2) ‹2› 7 6 4 - 1 (1)
Tarsus II Tibia II Genu II Femur II Trochanter II Coxal field II Tarsus III Tibia III Genu III Femur III Trochanter III Coxal field III Tarsus IV Tibia IV Genu IV Femur IV Trochanter IV Coxal field IV 2 (6) ((1)) 2 2 2 - (1) (6) 2 - 1 - 1 (1) n/a n/a n/a n/a n/a n/a 2 (6) ((1)) 2 2 2 - (1) (6) 2 - 1 - 2 (1) (5) 2 - - - - 2 (6) ((1)) 2 2 2 - (1) (6) 2 - 1 - 2 (1) (5) 2 - 1 - 1 2 (6) ((1)) 2 2 2 - (1) (6) 2 - 1 - 2 (1) (5) 2 - 1 - 1 2 (6) ((1)) 2 2 2 - (1) (6) 2 - 1 - 2 (1) (5) 2 - 1 - 1

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.


Ohio State University Acarology Laboratory


University of Stellenbosch


Smithsonian Institution, National Museum of Natural History


United States Department of Agriculture


Museum Donaueschingen