Hermanniella septentrionalis Berlese, 1910

Seniczak, Anna, Seniczak, Stanisław & Kowalski, Jarosław, 2022, Morphological ontogeny of Hermanniella septentrionalis (Acari, Oribatida, Hermanniellidae) and comments on Hermanniella Berlese, Zootaxa 5187 (1), pp. 121-148 : 123-141

Hermanniella septentrionalis Berlese, 1910

( Figs. 2–21 )

Diagnosis

Adult of medium size (length 520–699), with characters of Hermanniella given by Sitnikova (1975). Prodorsal setae le and in long, ro of medium size and ex short; le and in finely barbed, other setae smooth. Bothridium rounded, on large tubercle, bothridial seta of medium size, with small, barbed head. Adult bears tritonymphal scalp, with setae of medium size, but seta c 3 absent. After removing this scalp notogaster with 10 pairs of short setae, including f 1 (but c 3 absent), and 5 pairs of medium-sized setae in posterior part. Genital setae (7 pairs) in two rows: two in outer row (one longer and thicker than another), and five shorter pairs in inner row. Leg tarsi with one claw.

In larva of H. septentrionalis , most prodorsal setae of medium sized, except for long le, in nymphs le and in long, and other setae of medium size. Most gastronotal setae of juveniles of medium size, except for long h 1 and h 2 in larva, and p 1 and ad 1 in nymphs.

Morphology of adult

General morphology of adult of H. septentrionalis reminds this of H. punctulata redescribed by Aoki (1965) with tritonymphal scalp and studied by Weigmann (2006) without this scalp but differs from H. punctulata by the pattern on notogaster. It has smaller pits (vs. larger pits in H. punctulata ) and connecting lines (vs. no lines in H. punctulata ), like in the drawings of Berlese (1910), Grandjean (1931) and Weigmann (2006) but see Remarks. Body length (and range) 572.9±38.7 (520–650, n= 30) and width 370.3±31.9 (325–436). Prodorsal setae le and in long, ro of medium size and ex short ( Table 1 ); le and in finely barbed, other setae smooth ( Figs. 2a, 2c , 4a , 5a , 6 , 7a , 8c, 8d , 10c, 10d ). Bothridium rounded, on large tubercle, bothridial seta of medium size, with small, barbed head. Adult bears tritonymphal scalp, with setae of medium size, without seta c 3, h 1, h 2 and p -series ( Figs. 3 , 9 ). After removing this scalp notogaster with 10 pairs of short setae, including f 1 (but c 3 absent), and 5 pairs of medium size setae in posterior part ( Table 1 ), notogastral cerotegument with special pattern (2a, 2b, 6, 7, 8). Lyrifissure ia posterior to seta c 2, im close to posterodorsal base of large tubercle of opisthonotal gla opening, ip posterolateral to seta h 3, ian anterior to seta an 2, iad lateral to anterior part of anal plate, ips close and ih anterior to seta p 3 ( Figs. 4 , 5a ). Subcapitular setae short and smooth, but a thinner than other setae ( Figs. 4 , 10b ). Chelicera strong (length 165, width 72), chelate, seta cha longer than chb, both finely barbed ( Figs. 5b , 11a, 11b ). Palp relatively short (70) with smooth setae, inf on femur, all setae on tibia and cm on tarsus relatively long, solenidion ω long and curved anteriorly, pair pv absent ( Figs. 5c , 10b , 11b ). Formula of palp setae (trochanter to tarsus + solenidion ω): 0-2-1-3- 7(1).

All epimeral setae short and smooth ( Figs. 4a , 6c , 10b ), formula of epimeral setae 3-1-3-3. Genital setae (7 pairs) in two rows: two setae in outer row (one longer and thicker than another), and five shorter pairs in inner row ( Figs. 4 , 6c ). Aggenital setae (1 pair) short and smooth. Adanal setae (3 pairs) slightly longer than seta ag, length increasing from anterior to posterior. Anal setae (2 pairs) also short and smooth, length increasing from anterior to posterior.

Most leg setae smooth or finely barbed ( Figs. 6a–c , 10c, 10d , 11a, 11c, 11d , 12 , 13 ). Setae ft and u on all tarsi and solenidia on tarsus II relatively long, seta l' on femur IV and ft' on tarsus IV present. Seta d coupled to solenidion present on all genua and tibiae, but solenidion joined with seta and in light microscope difficult to observe, better observed in SEM micrographs ( Figs. 10c, 10d , 11c, 11d , 12 ). Formulae of leg setae (and solenidia), trochanter to tarsus: I – 1-5-4(1)-5(2)-18(2); II – 1-5-4(1)-5(1)-15(2); III – 2-3-2(1)-3(1)-15; IV – 1-3-2(1)-3(1)-13 ( Table 2 ). Leg tarsi monodactylous.

Remarks. Berlese (1910) differentiated H. septentrionalis (as H. punctulata septentrionalis ) from H. punctulata by having much smaller and more randomly distributed pits, vs. larger pits organized in longitudinal rows in H. punctulata . Grandjean (1931) distinguished H. septentrionalis (as H. punctulata septentrionalis ) from H. punctulata also by the presence of connecting lines between pits, which are lacking in H. punctulata . Weigmann (2006) recognized H. septentrionalis (as H. punctulata septentrionalis ) from H. punctulata by having rarely distributed pits, and some joined by the lines, as in Grandjean (1931). The same characteristics were also observed by Schatz (2020), although in some specimens connecting lines were hardly visible. In the SEM figures of H. septentrionalis studied herein and the figure prepared in the light microscope, some pits in the central part of notogaster are joined by the lines, as in individuals investigated by Grandjean (1931) and Weigmann (2006).

Description of juvenile stages

Larva egg-shaped ( Figs. 14 , 15a , 16a ), light brown. Prodorsum subtriangular, rostrum rounded. Prodorsal seta le long, other setae of medium size ( Table 1 ), setae le and in with short barbs, other setae smooth. Mutual distance between setal pair le slightly longer than between setal pair ro, and between setal pair in about 2.5 times longer than between setal pair ro; setal pair le inserted closer to in than to ro ( Figs. 14 , 16a ). Opening of bothridium small, rounded, bothridial seta setiform.

Gastronotum of larva with small tubercles and 13 pairs of setae, including f 1, placed posteromedial to seta e 1, and h 3 inserted lateral to anterior part of anal valves ( Figs. 14 , 15a , 16a ); most of medium size and with short barbs, except for clearly thicker f 1, longer h 1 and h 2, and short h 3 ( Table 1 ), all these setae smooth. Cupule ia posterolateral to seta c 3, im anterior to seta e 2, ip between setae h 1 and h 2, ih lateral to anterior part of anal valves. Opisthosomal gland opening anterolateral to seta e 2. Anal valves (segment P) glabrous. Leg segments relatively thick, and most leg setae smooth, except for barbed seta d on all femora and s and u on all tarsi; setae tc and u on all tarsi relatively long ( Fig. 17 ). Seta d present on all genua and tibiae at proper solenidia, but solenidion joined with seta and in light microscope difficult to observe.

Shape and colour of nymphs as in larva, but prodorsal setae ro, le in, and bs relatively longer, and bothridial seta long, fusiform, with barbed head. Gastronotum of protonymph with 16 pairs of setae because setae of p -series appearing and remaining in deutonymph and tritonymph ( Figs. 15b , 16b , 18 , 19 , 20 ). In protonymph, one pair of setae appearing on genital valves, and three pairs of shorter setae added in deutonymph and five pairs in tritonymph in inner row, and one pair of longer seta present in outer row ( Figs. 15b , 19 ). In deutonymph, pair of aggenital setae appearing, and present in tritonymph. Anal vales of protonymph (segments AD) and deutonymph (segments AN) glabrous, and of tritonymph with two pairs of short and smooth setae. In nymphs, most gastronotal setae of medium size with short barbs, except for longer p 1 and ad 1 ( Figs. 15b , 16b , 18 , 19 , 20 , Table 1 ), and gastronotal cerotegument with spines ( Figs. 9 , 20 ). In tritonymph, cupule ia posterior to seta c 3, im posterior to seta cp, ip between seta h 2 and p 2, iad antero-lateral to anal valves, and ips and ih lateral to iad ( Figs. 16b , 19b ). Opisthonotal gland opening anterolateral to seta h 3. Leg segments of tritonymph relatively thick and most setae of medium size and smooth, except for longer ft and u on all tarsi ( Fig. 21 ). Seta l' on femur IV and ft' on tarsus IV present, seta d present on all genua and tibiae at proper solenidia, but solenidion joined with seta and in light microscope difficult to observe.

Summary of ontogenetic transformations

In all juvenile instars of H. septentrionalis , the prodorsal seta le is longer than other setae, but in the larva ro is longer than in, whereas in the nymphs in is longer than ro. In the adult, seta in is longest, and le is longer than ro. Seta ex is short in all instars. In the larva, the bothridium is small and rounded, whereas in other instars it is larger and rounded, and in the adult it is located on large tubercle. In the larva, the bothridial seta is relatively short and setiform, whereas in other instars it is longer, fusiform, with finely barbed head. The larva has 13 pairs of gastronotal setae, including f 1 and h 3, the nymphs have 16 pairs, including f 1 (in protonymph p -series are added), whereas in the adult there are 15 pairs (c 3 is lost). The formula of gastronotal setae of H. septentrionalis is 13-16-16-16-15 (larva to adult, f 1 present). Formulae of epimeral setae are 3-1-2 (larva, including scaliform 1c), 3-1-3-1 (protonymph), 3-1-3-3 (deutonymph to adult). Formula of genital setae is 1-4-6-7 (protonymph to adult), aggenital setae is 1-1-1 (deutonymph to adult), and setae of segments PS−AN is 03333–0333–022. The ontogeny of leg setae and solenidia is given in Table 2 .

Note: structures are indicated where they are first added and are present through the rest of ontogeny; pairs of setae in parentheses, dash indicates no additions.

Distribution, ecology and biology

According to Subías (2004, updated 2022), H. septentrionalis has a Holarctic distribution (Western Palearctic: except North and Iran, and U.S.A.: Oregon). This species is mesohygrophilous, muscicolous and silvicolous ( Schatz 2008; Höpperger & Schatz 2013). It occupies different habitats from colline (i.e., hilly) to montane deciduous and mixed forests, colline meadows and wetlands, and montane pastures, xeric to wet ( Schatz 2020), but prefers the soils of moderate to moist deciduous forests ( Weigmann 2006) and is rather not abundant. In Poland, this species was recorded from Silesian mine dumps ( Bielska 1982) and was found in two other provinces ( Olszanowski et al. 1996), including Mazovia Province.

In this study, this species was collected at the edge of an old oak forest near Sierpc (Mazovia Province) but was not abundant. Among 30 individuals investigated, 37% of females were gravid and carried one or two large eggs (244 x 168), which comprised 43% of the length of females.

Figures

FIGURE 2. Hermanniella septentrionalis, adult. (a) Dorsal aspect, legs partially drawn, scale bar 50 μm; (b) pattern of notogaster; (c) apical part of seta le; (d) opistonothal gla opening, dorsolateral aspect (b−d enlarged).

FIGURE 3. Hermanniella septentrionalis, notogaster of adult with tritonymphal scalp, scale bar 50 μm.

FIGURE 4. Hermanniella septentrionalis, adult. (a) Ventral aspect, legs partially drawn, scale bar 50 μm; (b) hypostomal setae (enlarged).

FIGURE 5. Hermanniella septentrionalis, adult. (a) Lateral aspect, legs partially drawn, scale bar 50 μm; mouthparts, right side, (b) chelicera (Trägårdh organ in transparent area), scale bar 20 μm; (c) palp, scale bar 10 μm.

FIGURE 6. Hermanniella septentrionalis, adult, SEM micrographs. (a) Dorsal view, (b) lateral view, (c) ventral view, (d) prodorsal setae, frontal view.

FIGURE 7. Hermanniella septentrionalis, adult, SEM micrographs. (a) Medial part, lateral view; (b) posterior part, dorsal view; gla opening, (c) dorsal view, (d) lateral view.

FIGURE 8. Hermanniella septentrionalis, adult, SEM micrographs. Medial part of notogaster, (a) dorsal view, (b) lateral view, (c) anterior and medial part, lateral view, (d) bothridial seta, frontal view.

FIGURE 9. Hermanniella septentrionalis, adult with tritonymphal scalp, SEM micrographs. Lateral view, (a), (b), (c) medial part, (d) seta f1.

FIGURE 10. Hermanniella septentrionalis, adult, SEM micrographs. Ventral view, (a) posterior part, (b), anterior part; dorsolateral view, (c), (d) anterior part.

FIGURE 11. Hermanniella septentrionalis, adult, SEM micrographs. (a), (b) Mouthparts, frontal view; lateral aspect (c) parts of legs I, (d) legs I–III.

FIGURE 12. Hermanniella septentrionalis, adult, SEM micrographs, lateral view. (a) Part of legs I and II, (b) solenidia on tibia I, (c) leg II, (d) legs III and IV.

FIGURE 13. Hermanniella septentrionalis, leg segments of adult (part of femur to tarsus), right side, antiaxial aspect, scale bar 50 μm. (a) Leg I, (b) leg II, (c) leg III, (d) leg IV.

FIGURE 14. Hermanniella septentrionalis, larva. (a) Dorsal aspect, legs partially drawn, scale bar 20 μm.

FIGURE 15. Hermanniella septentrionalis, ventral part of hysterosoma, legs partially drawn, scale bar 20 μm. (a) Larva, (b) protonymph.

FIGURE 16. Hermanniella septentrionalis, lateral aspect, legs partially drawn, scale bars 50 μm. (a) Larva, (b) tritonymph.

FIGURE 17. Hermanniella septentrionalis, leg segments of larva (part of femur to tarsus), right side, antiaxial aspect, seta on the opposite side not illustrated is indicated in the legend, scale bar 10 μm. (a) Leg I, tarsus (pl'); (b) leg II; (c) leg III.

FIGURE 18. Hermanniella septentrionalis, posterior part of body, leg IV partially drawn, scale bar 50 μm. (a) Protonymph, (b) deutonymph.

FIGURE 19. Hermanniella septentrionalis, ventral part of hysterosoma, legs partially drawn, scale bar 50 μm. (a) Deutonymph, (b) tritonymph.

FIGURE 20. Hermanniella septentrionalis, tritonymph. (a) Dorsal aspect, legs partially drawn, scale bar 50 μm, (b) pattern of cerotegument (enlarged).

FIGURE 21. Hermanniella septentrionalis, leg segments of tritonymph (part of femur to tarsus), right side, antiaxial aspect, setae on the opposite side not illustrated are indicated in the legend, scale bar 20 μm. (a) Leg I, tarsus (pl'); (b) leg II, tibia (v'); (c) leg III; (d) leg IV; (e) part of tibia and tarsus I, dorsal aspect.

Tables

TABLE 1. Some morphological characters of instars of Hermanniella septentrionalis (mean measurements of 3–5

Morphological characters	Larva	Protonymph	Deutonymph	Tritonymph	Adult
Body length	257	358	475	592	570
Body width	139	228	286	345	370
Length of prodorsum	66	80	112	155	165
Length of: seta ro	22	24	30	40	69
seta le	30	36	46	77	114
seta in	16	30	39	72	115
seta bs	16	57	73	109	120
seta c 1	30	36	45	78	4
seta c 2	21	28	37	72	4
seta c 3	11	14	17	40	lost
seta cp	13	21	24	72	4
seta d 1	29	36	45	93	4
seta d 2	27	29	39	70	4
seta e 1	28	34	37	72	4
seta e 2	26	29	38	59	4
seta f 1	18	20	37	72	4
seta f 2	23	34	45	75	4
seta h 1	37	38	46	64	56
seta h 2	35	32	22	29	67
seta h 3	3	49	61	75	4
seta p 1	nd	59	77	99	64
seta p 2	nd	25	40	32	54
seta p 3	nd	18	21	23	51
seta ad 1	nd	nd	59	75	74
genital opening	nd	25	46	99	106
anal opening	74	86	102	158	145