Valgothrombium mariae, Mąkol, Joanna & Łaydanowicz, Joanna, 2010

Mąkol, Joanna & Łaydanowicz, Joanna, 2010, A new species of Valgothrombium Willmann, 1940, with additional taxonomic data for Valgothrombiinae genera known as larvae (Acari: Prostigmata: Microtrombidiidae), Zootaxa 2647, pp. 16-34 : 18-23

Valgothrombium mariae sp. nov.

Diagnosis. Larva.

Tritorostral setae (hypostomalae, bs) spine-like, with minute spicule near tip of the shaft. Scutum, scutellum and coxal plates with weakly marked reticular pattern. Scutum and scutellum, both with median ridge which extends into posterior and anterior protrusion respectively. Scutum almost as long as wide. Scutellum rounded pentagonal in outline, narrowing postero-laterally. NDV = 32. Setae 1a and 1b on coxae each with two setulae, setae 2b and 3b each with one setula. Tarsi I and II with two claws, tarsus III with two claws and claw-like empodium. IP> 700.

Adult, deutonymph. Not known.

Comparison. Larvae of Valgothrombium mariae sp. nov. differ from those of other members of the genus in the shape of the scutellum, which in V. m a r i a e is pentagonal in outline and narrowing postero-laterally (rectangular, oval or semi-circular in other Valgothrombium spp., except for V. natani and V. spasiscutum , where the general shape of the scutellum is similar to V. m a r i a e; differences apply to length/width ratio; for comparison see Figures 7–18 ), in the presence of a weakly marked reticulate pattern on the scutum, scutellum and coxal plates, and also in the length of the legs (IP = 797–815 in V. m a r i a e, IP <700 in Valgothrombium spp.).

Description. Larva (unengorged). Metric data given in Table 1 . Colour in life reddish. Idiosoma pearshaped, narrowing behind the level of setal rows C and D.

Gnathosoma ( Fig. 1 ). Cheliceral blade slightly curved, with small denticle in distal part of its inner edge. One pair of nude adoral setae (or) (7 µm). Ventrally a pair of spine-like subcapitular setae (tritorostral setae, hypostomalae, bs) (4 µm), each with minute distal spicule. Pedipalp formula: 0-0-0-NNN-NNNNNNζω. Palp femur and palp genu without setae. Palp tibia with one smooth seta (24 µm) and two shorter, thorn-like setae, the latter located close to the odontus base. Odontus divided for entire length. Palp tarsus with one long (30 µm) seta, five shorter spine-like setae (2–3 µm), one eupathidium (10–11 µm) and one prominent solenidion (8–9 µm).

LS—scutum length (= ASB + PSB); WS—scutum width measured at the widest part.

Idiosoma, dorsum ( Figs 2, 8 ). Scutum and scutellum with weak reticular pattern covering the entire surface of sclerites. Scutum rectangular in outline, with slight antero-medial protrusion and rounded anterolateral angles. Median line of the sclerite with longitudinal swollen cuticular ridge, especially distinct in posterior part of scutum and protruding behind its posterior margin. Setae AM and AL with setules. Setae PL thicker than AL and with short barbs distributed along the shaft. Sensillary setae (S) smooth. Scutellum with median ridge, which forms the anterior protrusion of the sclerite. Paired eyes at the level of posterior part of scutum. Each pair composed of anterior and posterior lens (anterior: 11–13 μm diameter, posterior: 9– 10), situated on an oval sclerite, which in unengorged specimen adjoins the postero-lateral margin of scutum. Scutellum bears one pair of barbed c1 setae (= SL), situated in posterior half of the sclerite and similar in shape to setae PL as well as to other setae of rows C-F. Setae of rows C-F barbed, especially in distal part of the shaft, and situated on plates; each seta inserted on a distinct cuticular protrusion within its plate. ƒD formula = 2(2)2-6-6-6-4. C row with setae c1-c3, D row with d1-d3, E row with e1-e3, F row with f1-f3 and H row with h1- h2. Setae f3 and h1-h2 located on the ventral side of idiosoma. Setae h1-h2 of comparable length to other dorsal setae, however, placed on more distinct tubercle-like protrusions and covered with relatively longer setules. Cuticle surrounding scutum, scutellum and setal plates smooth, in unengorged specimens folded in lines.

Idiosoma, venter ( Fig. 3 ). Cuticle smooth, in unengorged specimens folded in lines. Claparède’s organs (clp) placed laterally between coxae I and II; coxal plate I incorporates distinct cuticular border surrounding the area with Claparède’s organ. The surface of coxae with weakly marked reticulate pattern. Coxa I with seta 1a placed in antero-medial position and 1b in more lateral position in relation to 1a; both 1a and 1b with two setulae. Supracoxala I absent. Coxa II with seta 2b with one setula. Coxa III directed postero-laterally, with seta 3b with one setula. Intercoxalae 3a absent. ƒV formula = 2u-2. Shafts of two pairs ventral setae flanking anus thinner than dorsal setae. Anal opening without sclerites.

Legs ( Figs 4–6 ). Segmentation formula: 6-6-6. Leg chaetotaxy. Leg I: Tr (1n) - Fe (6n) - Ge (4n, 2σ, 1κ) - Ti (6n, 2φ, 1κ) - Ta (15n, 2ζ, 1ω, 1ε). Leg II: Tr (1n) - Fe (5n) - Ge (2n, 1σ) - Ti (5n, 2φ) - Ta (13n, 1ζ, 1ω, 1ε). Leg III: Tr (1n) - Fe (4n) - Ge (2n, 1σ) - Ti (5n) - Ta (12n). All normal setae on legs covered with barbs or setules, except for the most proximally placed, smooth seta on femora I-III, another smooth seta in a more distal position on femur II and one most distally placed on femur I. Proximal solenidion on genua I and II placed on part of segment base that fits into notch in distal margin of femora, sometimes giving the impression of being inserted on the most distal part of femora I and II, respectively. On tarsus I one subterminal eupathidium located dorsally, on distinct tubercle and one eupathidium placed ventrally, close to the base of tarsal claws. Tarsi I-II with paired claws ( Figs 4–5 ). Tarsus III ( Fig. 6 ) with normally developed claws, and claw-like empodium. All claws trifid apically, with two lateral spurs near the tip.

Etymology. The specific epithet is derived from the name Maria. We would like to dedicate the species to the late Dr. Maria Gulvik, the collector of Valgothrombium sp. nov. larvae, but - most of all - to the person we owe so much our debts will never be paid back.

Type material. Holotype, larva (coll. Norway, ad Skjolden, 61º29'25''N, 7º34'25''E, 50 m a.s.l., Alnus incana - Ulmus glabra woodland, rotten wood from a tree trunk, 8.05.2002, leg. M. Gulvik) and paratype, larva (the same data as for holotype) deposited in Biozentrum Grindel und Zoologisches Museum (formerly: Zoologisches Institut und Museum der Universität Hamburg), Hamburg, Germany (ZIZMUH).

Distribution. Norway.

Figures

FIGURE 1. Valgothrombium mariae sp. nov., larva, holotype. Gnathosoma, ventral view; or = adoral (protorostral) seta, bs = tritorostral seta (hypostomala), ω = solenidion on palp tarsus, ζ = eupathidium on palp tarsus. Palpal setae shown only on one side of symmetry axis.

FIGURE 3. Valgothrombium mariae sp. nov., larva, holotype. Ventral side of the body; legs omitted beyond trochanter; bs = tritorostral seta (hypostomala), only the base shown, clp = Claparède’s organ.

FIGURES 7 – 18. Scutum and scutellum in larvae of Valgothrombium spp. (setae omitted, actual distance between sclerites not retained). 7. V. valgum (George, 1909) (redrawn after Wohltmann and Wendt 1996). 8. V. m a r i a e sp. nov. 9. V. tarnavense (Feider, 1950) (redrawn after Feider 1955). 10. V. stuarti Baker, 1999 (redrawn after Baker 1999). 11. V. melindae Haitlinger, 2008 (orig., based on holotype). 12. V. natani Haitlinger, 2005 (orig., based on holotype). 13. V. paroense Haitlinger, 2009 (orig., based on holotype). 14. V. a v a e Haitlinger, 2005 (orig., based on holotype). 15. V. mallorcensis (Haitlinger, 2003) (orig., based on holotype). 16. V. fluminis (Michener, 1946) (redrawn after Michener 1946). 17. V. spasiscutum Robaux, 1974 (redrawn after Robaux 1974). 18. V. andreae (Saboori, Ueckermann & van Harten, 2007) (redrawn after Saboori et al. 2007).

FIGURES 4 – 6. Valgothrombium mariae sp. nov., larva. Legs I-III (trochanter - tarsus). 4. Leg I. 5. Leg II. 6. Leg III.

Tables

TABLE 1. Morphometric data for larvae of Valgothrombium mariae sp. nov.

Character	Holotype	Paratype	Character	Holotype	Paratype
LB	290	315	Cx I	60	62
WB	215	240	Tr I	29	31
LB/WB	1.35	1.31	Fe I	44	40
LS	96	95	Ge I	24	23
WS	106	108	Ti I	41	42
AA	37	35	Ta I L	65	63
AW	95	93	Ta I W	32	32
PW	82	93	Leg I	263	261
SB	60	63	Cx II	58	60
ASB	56	58	Tr II	33	29
PSB	40	37	Fe II	53	55
AP	51	53	Ge II	20	20
AM	38	-	Ti II	40	38
AL	47	40	Ta II	58	60
PL	60	63	Leg II	262	262
S	-	66	Cx III	63	67
MA	40	38	Tr III	35	30
HS	78	79	Fe III	54	45
LSS	130	121	Ge III	20	20
SL (=c1) SS	61 54	54 57	Ti III Ta III	48 70	47 65
pDS min	60	55	Leg III	290	274
pDS max	60	62	IP	815	797