Indopacifica impedimenta, Pfingstl & Minor & Schäffer & Shimano, 2023

Indopacifica impedimenta n. sp. Pfingstl, Minor & Shimano sp. nov.

LSID: urn:lsid:zoobank.org:act:A5170D5A-5D24-4E03-A744-C2AF02FD8815

Type material/locality

Holotype. Adult female (length 350 µm, width 234 µm); paratypes: 2 adult males (length 344/356 µm, width 228/231 µm)/ New Zealand, Auckland, Waiheke Island, Anzac Bay, next to Obrien Road ; 6 December 2022; green muddy algae growing on mangrove roots ( Conocarpus erectus ). Preserved in ethanol and deposited at the New Zealand National Arthropod Collection in Auckland.

Etymology. The specific name “impedimenta ” is given as noun in apposition. It is derived from the Latin meaning ’baggage’ or “impediment.” It first refers to the event of two of the authors having lost their baggage on their trip to New Zealand for the XVI International Congress of Acarology (ICA) 2022 and second, it is a tribute to this specific congress, which was successfully held despite the impediments at that time of existing worldwide COVID-19-crisis.

Diagnosis. Habitus and setal formulas typical for the genus (Pfingstl et al. 2019). Cerotegument conspicuous but fine granules over whole body. Prodorsal setae minute. Sensillum clavate, distally barbed. Slender triangular longitudinal elevation on prodorsum. Gastronotic region round in dorsal view, large but inconspicuous transversal depression on anterior part of notogaster. Median longitudinal depression on epimeron I, framed by a pair of parallel ridges. Two pairs of adanal setae. Claws long, thin, sickle-shaped with one proximoventral tooth.

Description of the adult

Measurements. Females (N = 1), length: 350 µm, width: 234 µm; males (N = 2), length: 344–356 µm (mean 350 µm), width: 228–231 µm (mean 230 µm).

Integument. Colour medium brown. Fine granular cerotegument covering whole body.

Prodorsum ( Figure 1a View Figure 1 ). Rostrum rounded in dorsal view, clearly demarcated from remainder of prodorsum by transverse ridge. Pair of anteriorly converging faint prodorsal ridges, difficult to observe. A broad but faint triangular median longitudinal elevation reaching from interbothridial area to demarcation of rostrum. Rostral (ro) and lamellar seta (le) minute, difficult to observe. Interlamellar seta (in) minute, exobothridial seta (ex) vestigial. Bothridium large cup with lateral incision. Bothridial seta (ca. 45 µm) slightly clavate, distally barbed, and laterally flattened.

Gnathosoma. Chelicera chelate, with two teeth on each digit. Setae cha and chb of approximately same length, both dorsally slightly pectinate. Palp setal formula 0-2-1-3-8 (+ solenidion ω). Distal part of rutellum developed as thin, triangular, slightly inwardly curved membrane with longitudinal incision. Setae a - and m long, smooth (ca. 17 µm). Mentum regular, finely granular, seta h simple, long (ca. 28 µm).

Notogastral region ( Figure 1a View Figure 1 ). Notogaster rounded, nearly circular in dorsal view. Dorsosejugal articulation incomplete. A semicircular transverse cuticular depression adjacent to anterior border of notogaster. A median lighter rectangular area with irregular contours adjacent to anterior border of notogaster. Fourteen pairs of thin, short setiform notogastral setae (length 5–10 µm), c 1, c 2, da, dm, dp, la, lm, lp, h 1–3, p 1–3; c 3 absent. Orifice of opisthonotal gland gla anterior to seta la. Lyrifissure im laterally between setae la and lm.

Podosoma and venter ( Figure 1b View Figure 1 ). Median longitudinal, rectangular-shaped depression reaching from epimeres I to epimeres III, on epimeres I this depression is laterally delimited by a pair of distinct cuticular ridges. Indistinct circular depression on posterior border of epimeres III, anterior of genital orifice. Epimeral setation 1-0-1-1, setae 1a long (ca. 35 µm), fine, setae 3a and 4a very short (5–8 µm). Three pairs of short (ca. 5 µm), fine genital setae present. Preanal organ triangular in ventral view, interior part anchorshaped. Two pairs of minute (1–3 µm) adanal setae ad 1–2 and two pairs of minute (1–3 µm) anal setae an 1–2 present. Lyrifissure iad oblique, framing anterior border of anal opening.

Lateral aspect ( Figure 1c View Figure 1 ). A broad lateral furrow reaching from dorsal to ventral sejugal scissure. Pedotectum I PtI present, round, small, pedotectum II absent. Lateral enantiophysis consisting of two opposite projections (s 1, s 2); the anterior rounded, the posterior pointed and elongated. Discidium di developed as prominent conical bulge.

Legs ( Figure 2 View Figure 2 ). Monodactylous, long hook-like slender claw with one acute distinct proximoventral tooth and slight serration on proximal dorsal edge. Cerotegument granular. No porose areas detectable. Indistinct ventral carina on femur I and II. Lateral setae l of all genua scale-like, broadened, short, and blunt. Setation (first set of numbers, given in the order trochanter-femur-genu-tibiatarsus) and solenidia (second set of numbers, given in the order genu-tibia-tarsus): Leg I (0-3-2-3-18) (1-2-2), leg II (0-3-2-3-15) (1-1-1), leg III (1-2-1-2-13) (1-1-0), leg IV (1-2-1-3-12) (0-1-0).

Remarks

The new species can be distinguished from congeneric species by its minute notogastral setae (5–10 µm), all other species show distinctly longer setae (10–16 µm). There is also a slender triangular median longitudinal elevation on the prodorsum of the new species, such an elevation is lacking in Indopacifica iohanna and I. pantai and is conspicuously less developed in I. parva , I. mauritiana , I. taiyo and I. tyida . An obvious depression on epimeres I is present in all Indopacifica species but in none is it framed by distinct straight parallel ridges as shown in the new species.

Distribution. This species has yet only been found in a single location on Waiheke Island, New Zealand. A wider distribution along the warmer northern shorelines of the North Island should be considered. This is also the first record of a member of the family Selenoribatidae from New Zealand and represents the southernmost occurrence of this group.

Ecology. Specimens occurred in algae patches growing on mangrove roots; therefore, we can assume that this species prefers to dwell in mangrove habitats. Moreover, the claws of this species are slender and weakly curved, which is indicative for typical mangrove-dwelling oribatid mites ( Pfingstl et al. 2020).

Description of juveniles

Common features of juvenile stages. Colour brown. Integument plicate and soft, except for centrodorsal plate. Whole cerotegument showing dense granulation. Prodorsum triangular, rostrum rounded.

Rostral, lamellar and interlamellar setae minute, exobothridial seta shaped like minute lamella. Sensillum clavate, distally spinose. Bothridium cup-like. Large centrodorsal plate bearing centrodorsal setae. Centrodorsal plate slightly convex, plateau-like; lateral and posterior inner borders of plate deepened like broad furrow. Large folds completely framing centrodorsal plate. Ventral furrows typical for selenoribatid juveniles. Legs, tarsus I with short knob-like famulus, no porose areas on femora detectable, genua with broadened scale-like lateral setae, claws with one sharp proximoventral tooth.

Larva. (N = 3) length: 203 (all showed the same length).

Prodorsum: All prodorsal setae minute, lamellar (le) and rostral (ro) setae very difficult to observe.

Gastronotic region ( Figure 3a View Figure 3 ). Eleven pairs of short (ca. 8 µm), spiniform and smooth notogastral setae; c 1–3, da, dm, dp, la, lm, lp, h 1–2; h 3 absent; h 2 slightly longer than others (ca. 10 µm).

Podosoma and venter. Epimeral setation 1-0-1, epimeral seta 1a conspicuously longer (15 µm) than 3a (ca. 6 µm). Claparède’s organ clp globular.

Legs. Setation and solenidia: leg I (0-2-2-3-16) (1-1-1), leg II (0-2-2-2-13) (1-1-1), leg III (0-2-1-1-13) (1-1-0).

Protonymph. (N = 4) length: 231–246 μm (mean 242).

Gastronotic region ( Figure 3b View Figure 3 ). Fifteen pairs of notogastral setae; c 1–3, da, dm, dp, la, lm, lp, h 1–3 and p 1–3, all short, spiniform, approximately the same length (8–10 µm).

Podosoma and venter. Epimeral setation 1-0-1-1. Seta 4a medially on epimeron IV. One pair of short genital setae. Aggenital setae absent.

Legs. Setation and solenidia: leg I (0-3-2-3-16) (1-1-2), leg II (0-3-2-2-13) (1-1-1), leg III (0-2-1-1-13) (1-1-0), leg IV (0-0-0-0-7) (0-0-0).

Deutonymph. (N = 1) length: 305 μm.

Gastronotic region. Fifteen pairs of notogastral setae, same positions and shapes as in protonymph, all of approximately the same length (10 µm).

Podosoma and venter. Epimeral setation 1-0-1-1. Two pairs of short genital setae (approx. 4 µm) arranged in a longitudinal row. Two pairs of adanal setae ad 1–2 (6–8 µm) flanking anal valves.

Legs Figure 3c–f View Figure 3 . Setation and solenidia: leg I (0-3-2-3-16) (1-2-2), leg II (0-3-2-2-13) (1-1-1), leg III (0-2-1-1-13) (1-1-0), leg IV (0-2-1-1-12) (0-1-0).

Tritonymph. (N = 1) length: 381 μm.

Gastronotic region. No difference to deutonymph.

Podosoma and venter. Epimeral setation 1-0-1-1.

Three pairs of short genital setae in longitudinal row. Two pairs of adanal setae ad 1–2 and two pairs of minute anal setae an 1–2.

Legs. Setation and solenidia: leg I (0-3-2-3-18) (1-2-2), leg II (0-3-2-3-15) (1-1-1), leg III (0-2-1-1-13) (1-1-0), leg IV (0-2-1-2-12) (0-1-0).

Remarks

Presently, only juveniles of Indopacifica iohanna , I. taiyo and I. tyida are known ( Resch et al. 2019; Pfingstl et al. 2021) and the immatures of the new species show an identical habitus, notogastral and ventral setation. Juvenile stages of I. iohanna lack a proximoventral tooth on their claws and thus can be easily distinguished from immatures of the new species. This proximoventral tooth, however, is present in nymphs of I. taiyo and I. tyida , but these show only two setae on tibia I whereas immatures of the new species show already three setae on this segment from the larva. Apart from these characters, there is no way to distinguish the juveniles of Indopacifica species.