Leptus molochinus (C. L. Koch, 1837 )

Laydanowicz, Joanna & Mąkol, Joanna, 2010, Correlation of heteromorphic life instars in terrestrial Parasitengona mites and its impact on taxonomy - the case of Leptus molochinus (C. L. Koch, 1837) and Leptus ignotus (Oudemans, 1903) (Acari: Trombidiformes: Prostigmata: Erythraeidae), Journal of Natural History 44 (11 - 12), pp. 669-697 : 672-688

publication ID	https://doi.org/ 10.1080/00222930903383560
persistent identifier	https://treatment.plazi.org/id/A72087F2-FFF9-BB09-FE7D-FC55FCABFBFE
treatment provided by	Felipe
scientific name	Leptus molochinus (C. L. Koch, 1837 )
status

Treatment

Leptus molochinus (C. L. Koch, 1837) View in CoL

Rhyncholophus molochinus C. L. Koch, 1837

Leptus ignotus ( Oudemans, 1903) , syn. nov.

For other synonyms see Southcott (1961, 1992).

Diagnosis

Adult and deutonymph. Anterior sensillary area of crista metopica oval, elongated. Posterior sensillary area with posterior process. Dorsal idiosomal setae relatively short (<45), stout, with uniform acuminate setules outgoing from the main stem.

Larva. One seta on palp femur and palp genu. Four intercoxalae at level of coxae IV. Tibia I (<120) with two solenidia (ϕ). ISD = 58–75; Ti III/AW ≤ 1.72; DSmax <70; L/W 0.87–1.12; Ti III 105–134. For other characters see diagnosis of the genus.

Description

Adult and deutonymph. ( Figures 1–6 View Figure 1 View Figure 2 View Figure 3 View Figure 4 View Figure 5 View Figure 6 ). For morphometric data see Table 1. Colour in life brownish. Body oval in shape, slightly widened anteriorly ( Figure 1 View Figure 1 ) and densely covered with uniform setae. Chelicerae narrow, dagger-like, retractable into idiosoma. Palps ( Figure 2 View Figure 2 ) slender. Palp genu almost parallel-sided, palp tibia triangular in outline, palp tarsus slightly longer than wide and rounded terminally. Odontus simple, relatively short, hook-like. All segments of palps covered with sparsely distributed setae. All setae on palp trochanter and palp tibia, as well as those that cover the medial and lateral side of palp femur and palp genu, elongated, slender, covered with short, delicate setules. Setae placed at dorsal side of palp femur and palp genu more stout, similar to normal setae covering leg segments. Numerous setae with very short setules present on palp tarsus.

Crista metopica ( Figure 3 View Figure 3 ) elongated. Anterior sensillary area oval, with two sensillary setae (ASens) placed slightly behind the mid level of sensillary area and covered with setules along the entire stem. Rod of crista narrow, parallel-sided. Posterior sensillary area drop-like in shape, with two sensillary setae (PSens) moved to the posterior margin of sensillary area. PSens longer than ASens and covered with slightly shorter setules. Posterior process of crista weakly marked, shorter than posterior sensillary area of crista. Eyes ( Figure 3 View Figure 3 ) sessile, each composed of single circular lens, placed laterally to the rod of crista metopica, at the level of anterior part of crista, close to half its length. Dorsal opisthosomal setae ( Figures 5 View Figure 5 , 6A View Figure 6 ) uniform in shape, slightly longer at aspidosoma. Setae oval in outline, stout, densely covered with setules outgoing from the main stem. Setules relatively thick at base, then acuminate. Ventral setae similar to those placed on idiosoma dorsum, also uniform but more slender and with more delicate setules. Genital opening ( Figure 4 View Figure 4 ) surrounded by centrovalves and epivalves. Centrovalval setae delicate, covered with setules, which are more densely distributed in proximal part of the stem. Epivalval setae similar in length to centrovalval ones but stouter and with setules covering the entire stem. In females, two pairs of genital acetabulae, sometimes both pairs shifted to one side of genital opening. Anal opening ( Figure 4 View Figure 4 ) surrounded by paired valves. Medial valves membraneous, with a row of delicate, sparsely setulose setae arising along the medial margin of each valve. Lateral valves sclerotised, with several setae, which are stouter than those covering the medial valves and arise along the lateral margin of each sclerite.

Legs IV slightly longer than legs I. Legs II and III the shortest ( Figure 1 View Figure 1 ). Leg segments covered with setae of different type: normal, densely setulose setae ( Figure 6B View Figure 6 ) present on all leg segments, confined on tarsi to dorsal part of the segment; more slender and more sparsely setulose setae ( Figure 6C View Figure 6 ) present also on coxae; normal, brush-like setae ( Figure 6F View Figure 6 ) aggregated along the ventral side of tarsi [setae covering tarsi gradually pass from the robust ones ( Figure 6B View Figure 6 ), which are located dorsally, into brush-like setae ( Figure 6F View Figure 6 ), which dominate along the ventral part of the segment]; few setae, covered with very short setules ( Figure 6D View Figure 6 ), sparsely distributed on all segments, beyond trochanters; few setae of the same type, however slightly thicker and longer ( Figure 6E View Figure 6 ) located ventrally at termination of tibiae II–IV; setae of “eupathidium type ” ( Figure 6G View Figure 6 ) (spinalae according to Southcott (1961) arise along the dorsal side of all telofemora, genua, tibiae and on tarsus I; c. 3–4 vestigialae ( Figure 6H View Figure 6 ), narrowed apically, located distally on tibia I, few solenidia ( Figure 6I View Figure 6 ) scattered between spinalae on tarsus I; famulus ( Figure 6J View Figure 6 ), rounded apically, present on terminal part of tarsus I.

Larva ( Figures 7–15 View Figure 7 View Figure 8 View Figure 9 View Figure 10 View Figure 11 View Figure 12 View Figure 13 View Figure 14 View Figure 15 ). For morphometric data see Table 2. Gnathosoma ( Figures 7–9 View Figure 7 View Figure 8 View Figure 9 , 11 View Figure 11 , 12 View Figure 12 ): chelicera composed of basal segment and movable claw. Dorsal side of gnathosoma ( Figure 8 View Figure 8 ) with a pair of setiform adoral setae (cs) placed anteriorly and a pair of club-shaped supracoxal setae (elcp) located posterolaterally. Ventrally on gnathosoma ( Figure 9 View Figure 9 ) a pair of very short (ca. 3) spine-like setae (as) and a pair of subcapitular (tritorostral) setae (bs), covered with few short setules. Pedipalp formula: 0-B-B-BBN-NNBBB wz. Palp femur and palp genu ( Figures 8 View Figure 8 , 9 View Figure 9 ) with one setulose seta. Palp tibia ( Figures 8 View Figure 8 , 9 View Figure 9 ) with two barbed setae and one smooth spinelike seta, the latter located close to the odontus base. Odontus simple. Palp tarsus ( Figures 7 View Figure 7 , 12 View Figure 12 ) with five normal setae, of which three are covered with distinct setules and the remaining two are smooth, one solenidion (w) located in proximal part of the segment and one prominent distal eupathidium (z).

Dorsal side of idiosoma: scutum ( Figure 8 View Figure 8 ) triangular in outline, the widest anteriorly, rounded at corners, with two pairs of non-sensillary setae (AL and PL) and two pairs of trichobothria (ASens and PSens). Setae AL slightly shorter than PL, both thickened and covered with setules along the entire stem. ASens shorter than PSens, both with setules covering the distal half of the stem. Single eyes on circular sclerites located at the level of posterior part of scutum. The remaining part of idiosoma with cuticle folded in lines. Dorsal setae situated on small platelets and covered with setules evenly distributed along the entire stem. The number of setae in f D formula, except for those located on scutum, varies between 56 and 69 (n = 5).

Ventral side of idiosoma ( Figure 9 View Figure 9 ): ventral setae (including coxalae and intercoxalae) similar to those covering the idiosoma dorsum but slightly narrower at termination. The number of setae in f V formula, except for coxalae and intercoxalae I, II, III varies between 28 and 37 (n = 5), which makes the total number of setae in f D and f V formula 93–100. Coxal setation formula: 1-1-1. Setae 1b, 2b, 3b located on coxae I, II, III respectively; 1b in centrolateral position, 2b in posterolateral position and 3b shifted to anterior margin of coxal plate. Setae 1a, 2a, 3a 1 –a 2 placed between coxal plates I, II, III, respectively; 1a, at the level of symmetry axis of coxa I; 2a, slightly moved to the level of anterior part of coxa II; 3a 1, before the level of coxa III; and 3a 2, at the level of symmetry axis of coxa III.

Legs ( Figures 10 View Figure 10 , 13–15 View Figure 13 View Figure 14 View Figure 15 ): leg segmentation formula: 7-7-7. For leg chaetotaxy see Table 3. Normal setae on legs covered with setules. Setae on trochanters stouter than those covering the remaining leg segments. Solenidia present on genu I, tibia I and tarsus I, tibia II ( Figure 13 View Figure 13 ) and tarsus II and also on tibia III. Tarsal solenidia stouter than the others. Vestigialae present on genu I, tibia I and on genu II ( Figure 13 View Figure 13 ). Famulus on tarsus I located anteriorly to solenidion. Subterminal eupathidia present on tarsi I–III. All tarsi terminated with two claws and claw-like empodium ( Figures 10 View Figure 10 , 14 View Figure 14 , 15 View Figure 15 ). Anterior claw stout, with short hairy setules covering threequarters of its length, proximally. Posterior claw feather-like. Claws without terminal hooks. Empodium with very short setules, evenly distributed along the whole shaft. The cuticle covering tarsi arranged in transverse folds ( Figure 14 View Figure 14 ), especially distinct in distal part of the segments (character visible with both light and scanning electron microscopes).

Type material

Neotype. Female ( PL – H/941) collected in Wroclaw (south-west Poland), on the Odra R. shore (51º05′43′′ N, 17º05′37′′ E), 3 June 2005, by J. Laydanowicz, deposited at Biocentrum Grindel und Zoologisches Museum, Hamburg ( ZIMH), Germany. GoogleMaps

Additionally, three larvae of L. molochinus , obtained from female selected as neotype, deposited in ZIMH. The remaining material is in the author’s collection ( Institute of Biology , Department of Invertebrate Systematics and Ecology , Wroclaw University of Environmental and Life Sciences) .

Distribution

Europe.

Biology

Besides the members of Leptus , preliminarily assigned to two distinct species, another 10 species of Parasitengona terrestria were recorded sympatrically from the study plot ( Laydanowicz and Mąkol 2008). Altogether, 62 adults of L. molochinus (29 females, nine males, 24 adults of undetermined sex), four postlarval specimens not assigned to the stage, one protonymph and 17 larvae, preliminarily assigned to “ L. ignotus ”, were collected in the field. Adults were observed in the field from the end of May until the beginning of July, with the highest abundance in June (58 specimens, including 26 females, eight males, 24 adults of undetermined sex). The only deutonymph emerged under laboratory conditions from a protonymph that was collected in the field in March. Larvae of “ L. ignotus ” were collected in the field from mid-August for about 5 weeks. Field-collected females deposited eggs under laboratory conditions. The time between collecting of the female and oviposition varied between 3 and 21 days (n = 29, mean = 9.1). The emergence of larvae during the laboratory experiment was observed from the beginning of July until the beginning of August. The number of larvae that emerged from eggs deposited by one female varied between 3 and 138 (n = 29, mean = 41.7) and the time that elapsed between oviposition and appearance of larvae ranged from 23 to 32 days (n = 10, mean = 26.6).

Of the total number of field-collected larvae, 11 specimens were collected together with hosts. Specification of host taxa is given in Table 4. In most cases one parasite was observed on a particular host, except for two cases in which two specimens were found on Opiliones and Acari . Attachment site on the host varied and no site preference was observed. Similarly, no change of the chosen attachment site was observed during the parasitic phase. The larvae detached from the host easily, usually as a result of mechanical irritation, which in case of insufficiently engorged specimens made further development into a protonymph impossible.