Anomalohalacarus angustus Shin, Chang and Lee, 2024

Shin, Jong Hak, Chang, Cheon Young & lee, Jimin, 2024, Two psammobiont species of Anomalohalacarus (Acari, Halacaridae) from South Korea, Biodiversity Data Journal 12, pp. e 135719-e 135719 : e135719-

Anomalohalacarus angustus Shin, Chang and Lee sp. nov.

Anomalohalacarus Newell, 1949

Type species: Anomalohalacarus anomalus (Trouessart, 1894)

Materials

Type status: Holotype. Occurrence: individualCount: 1; sex: female; lifeStage: adult; preparations: dissected, mounted in glycerine on H-S slide; occurrenceID: 4A860B8C-956E-53AC-A1A6-5C8E89EF3528; Taxon: scientificName: Anomalohalacarus angustus ; kingdom: Animalia; phylum: Arthropoda; class: Arachnida; order: Trombidiformes ; family: Halacaridae ; genus: Anomalohalacarus ; specificEpithet: angustus ; scientificNameAuthorship: Shin, Chang & Lee; Location: higherGeography: Northwest Pacific Ocean; continent: East Asia; country: Korea (the Republic of); countryCode: KR; stateProvince: Gyeongsangbuk-do; municipality: Pohang-city; locality: Chilpo Beach, Heunghee-eup ; verbatimDepth: 0.5–1 m; verbatimCoordinates: 36 ° 07 ' 59 " N 129 ° 23 ' 57 " E; Identification: identifiedBy: Shin, Chang & Lee; dateIdentified: 2024; Event: samplingProtocol: suction; eventDate: 26 / 04 / 2023; Record Level: institutionID: MABIK CR 00257793; institutionCode: Marine Biodiversity Institute of Korea; basisOfRecord: PreservedSpecimen

Type status: Paratype. Occurrence: individualCount: 1; sex: male; lifeStage: adult; preparations: mounted in glycerine on H-S slide; occurrenceID: 879F85D4-A825-544B-8000-A6668FE095A2; Taxon: scientificName: Anomalohalacarus angustus ; kingdom: Animalia; phylum: Arthropoda; class: Arachnida; order: Trombidiformes ; family: Halacaridae ; genus: Anomalohalacarus ; specificEpithet: angustus ; scientificNameAuthorship: Shin, Chang & Lee; Location: higherGeography: Northwest Pacific Ocean; continent: East Asia; country: Korea (the Republic of); countryCode: KR; stateProvince: Gyeongsangbuk-do; municipality: Pohang-city; locality: Chilpo Beach, Heunghee-eup ; verbatimDepth: 0.5–1 m; verbatimCoordinates: 36 ° 07 ' 59 " N 129 ° 23 ' 57 " E; Identification: identifiedBy: Shin, Chang & Lee; dateIdentified: 2024; Event: samplingProtocol: suction; eventDate: 26 / 04 / 2023; Record Level: institutionID: MABIK CR 00257794; institutionCode: Marine Biodiversity Institute of Korea; basisOfRecord: PreservedSpecimen

Type status: Paratype. Occurrence: individualCount: 1; sex: female; lifeStage: adult; preparations: mounted in glycerine on H-S slide; occurrenceID: 3F900439-5D5F-5893-8C7B-D12B1F8406D3; Taxon: scientificName: Anomalohalacarus angustus ; kingdom: Animalia; phylum: Arthropoda; class: Arachnida; order: Trombidiformes ; family: Halacaridae ; genus: Anomalohalacarus ; specificEpithet: angustus ; scientificNameAuthorship: Shin, Chang & Lee; Location: higherGeography: Northwest Pacific Ocean; continent: East Asia; country: Korea (the Republic of); countryCode: KR; stateProvince: Gyeongsangbuk-do; municipality: Pohang-city; locality: Chilpo Beach, Heunghee-eup ; verbatimDepth: 0.5–1 m; verbatimCoordinates: 36 ° 07 ' 59 " N 129 ° 23 ' 57 " E; Identification: identifiedBy: Shin, Chang & Lee; dateIdentified: 2024; Event: samplingProtocol: suction; eventDate: 26 / 04 / 2023; Record Level: institutionID: MABIK CR 00257795; institutionCode: Marine Biodiversity Institute of Korea; basisOfRecord: PreservedSpecimen

Type status: Paratype. Occurrence: individualCount: 1; sex: male; lifeStage: adult; preparations: mounted in glycerine on H-S slide; occurrenceID: 5963AC3E-403D-5602-BB64-E42B60E57386; Taxon: scientificName: Anomalohalacarus angustus ; kingdom: Animalia; phylum: Arthropoda; class: Arachnida; order: Trombidiformes ; family: Halacaridae ; genus: Anomalohalacarus ; specificEpithet: angustus ; scientificNameAuthorship: Shin, Chang & Lee; Location: higherGeography: Northwest Pacific Ocean; continent: East Asia; country: Korea (the Republic of); countryCode: KR; stateProvince: Gyeongsangbuk-do; municipality: Pohang-city; locality: Chilpo Beach, Heunghee-eup ; verbatimDepth: 0.5–1 m; verbatimCoordinates: 36 ° 07 ' 59 " N 129 ° 23 ' 57 " E; Identification: identifiedBy: Shin, Chang & Lee; dateIdentified: 2024; Event: samplingProtocol: suction; eventDate: 26 / 04 / 2023; Record Level: institutionID: MABIK CR 00257796; institutionCode: Marine Biodiversity Institute of Korea; basisOfRecord: PreservedSpecimen

Type status: Paratype. Occurrence: individualCount: 1; sex: male; lifeStage: adult; preparations: mounted in glycerine on H-S slide; occurrenceID: 71CEE945-3FB9-559C-9F54-26F7E1A34437; Taxon: scientificName: Anomalohalacarus angustus ; kingdom: Animalia; phylum: Arthropoda; class: Arachnida; order: Trombidiformes ; family: Halacaridae ; genus: Anomalohalacarus ; specificEpithet: angustus ; scientificNameAuthorship: Shin, Chang & Lee; Location: higherGeography: Northwest Pacific Ocean; continent: East Asia; country: Korea (the Republic of); countryCode: KR; stateProvince: Gyeongsangbuk-do; municipality: Pohang-city; locality: Chilpo Beach, Heunghee-eup ; verbatimDepth: 0.5–1 m; verbatimCoordinates: 36 ° 07 ' 59 " N 129 ° 23 ' 57 " E; Identification: identifiedBy: Shin, Chang & Lee; dateIdentified: 2024; Event: samplingProtocol: suction; eventDate: 26 / 04 / 2023; Record Level: institutionID: MABIK CR 00257797; institutionCode: Marine Biodiversity Institute of Korea; basisOfRecord: PreservedSpecimen

Type status: Paratype. Occurrence: individualCount: 1; sex: female; lifeStage: adult; preparations: mounted in glycerine on H-S slide; occurrenceID: 9E5317B9-7BD6-5F6D-9F29-9554DEC19FEA; Taxon: scientificName: Anomalohalacarus angustus ; kingdom: Animalia; phylum: Arthropoda; class: Arachnida; order: Trombidiformes ; family: Halacaridae ; genus: Anomalohalacarus ; specificEpithet: angustus ; scientificNameAuthorship: Shin, Chang & Lee; Location: higherGeography: Northwest Pacific Ocean; continent: East Asia; country: Korea (the Republic of); countryCode: KR; stateProvince: Gyeongsangbuk-do; municipality: Pohang-city; locality: Chilpo Beach, Heunghee-eup ; verbatimDepth: 0.5–1 m; verbatimCoordinates: 36 ° 07 ' 59 " N 129 ° 23 ' 57 " E; Identification: identifiedBy: Shin, Chang & Lee; dateIdentified: 2024; Event: samplingProtocol: suction; eventDate: 26 / 04 / 2023; Record Level: institutionID: MInRB-Hl 20 - S 006; institutionCode: Marine Interstitial fauna Resources Bank; basisOfRecord: PreservedSpecimen

Type status: Paratype. Occurrence: individualCount: 1; sex: male; lifeStage: adult; preparations: mounted in glycerine on H-S slide; occurrenceID: 94E1D3FE-765A-50A2-84C1-43F186EEDA48; Taxon: scientificName: Anomalohalacarus angustus ; kingdom: Animalia; phylum: Arthropoda; class: Arachnida; order: Trombidiformes ; family: Halacaridae ; genus: Anomalohalacarus ; specificEpithet: angustus ; scientificNameAuthorship: Shin, Chang & Lee; Location: higherGeography: Northwest Pacific Ocean; continent: East Asia; country: Korea (the Republic of); countryCode: KR; stateProvince: Gyeongsangbuk-do; municipality: Pohang-city; locality: Chilpo Beach, Heunghee-eup ; verbatimDepth: 0.5–1 m; verbatimCoordinates: 36 ° 07 ' 59 " N 129 ° 23 ' 57 " E; Identification: identifiedBy: Shin, Chang & Lee; dateIdentified: 2024; Event: samplingProtocol: suction; eventDate: 26 / 04 / 2023; Record Level: institutionID: MInRB-Hl 20 - S 007; institutionCode: Marine Interstitial fauna Resources Bank; basisOfRecord: PreservedSpecimen

Type status: Paratype. Occurrence: individualCount: 1; sex: male; lifeStage: adult; preparations: mounted in glycerine on H-S slide; occurrenceID: 95FAE6B4-DA3D-563D-964C-8E0E8789E8A2; Taxon: scientificName: Anomalohalacarus angustus ; kingdom: Animalia; phylum: Arthropoda; class: Arachnida; order: Trombidiformes ; family: Halacaridae ; genus: Anomalohalacarus ; specificEpithet: angustus ; scientificNameAuthorship: Shin, Chang & Lee; Location: higherGeography: Northwest Pacific Ocean; continent: East Asia; country: Korea (the Republic of); countryCode: KR; stateProvince: Gyeongsangbuk-do; municipality: Pohang-city; locality: Chilpo Beach, Heunghee-eup ; verbatimDepth: 0.5–1 m; verbatimCoordinates: 36 ° 07 ' 59 " N 129 ° 23 ' 57 " E; Identification: identifiedBy: Shin, Chang & Lee; dateIdentified: 2024; Event: samplingProtocol: suction; eventDate: 26 / 04 / 2023; Record Level: institutionID: MInRB-Hl 20 - S 008; institutionCode: Marine Interstitial fauna Resources Bank; basisOfRecord: PreservedSpecimen

Type status: Paratype. Occurrence: individualCount: 1; sex: male; lifeStage: adult; preparations: mounted in glycerine on H-S slide; occurrenceID: 599E0D65-6CAA-5B02-8549-B44A4AB5CB01; Taxon: scientificName: Anomalohalacarus angustus ; kingdom: Animalia; phylum: Arthropoda; class: Arachnida; order: Trombidiformes ; family: Halacaridae ; genus: Anomalohalacarus ; specificEpithet: angustus ; scientificNameAuthorship: Shin, Chang & Lee; Location: higherGeography: Northwest Pacific Ocean; continent: East Asia; country: Korea (the Republic of); countryCode: KR; stateProvince: Gyeongsangbuk-do; municipality: Pohang-city; locality: Chilpo Beach, Heunghee-eup ; verbatimDepth: 0.5–1 m; verbatimCoordinates: 36 ° 07 ' 59 " N 129 ° 23 ' 57 " E; Identification: identifiedBy: Shin, Chang & Lee; dateIdentified: 2024; Event: samplingProtocol: suction; eventDate: 26 / 04 / 2023; Record Level: institutionID: MInRB-Hl 20 - S 009; institutionCode: Marine Interstitial fauna Resources Bank; basisOfRecord: PreservedSpecimen

Type status: Other material. Occurrence: individualCount: 1; sex: female; lifeStage: adult; preparations: mounted in glycerine on H-S slide; occurrenceID: 85DBD274-A2A1-50D1-9A62-8E8B40555A94; Taxon: scientificName: Anomalohalacarus angustus ; kingdom: Animalia; phylum: Arthropoda; class: Arachnida; order: Trombidiformes ; family: Halacaridae ; genus: Anomalohalacarus ; specificEpithet: angustus ; scientificNameAuthorship: Shin, Chang & Lee; Location: higherGeography: Northwest Pacific Ocean; continent: East Asia; country: Korea (the Republic of); countryCode: KR; stateProvince: Gyeongsangnam-do; municipality: Geoje-city; locality: Gujora Beach, Gujora-ri, Irun-myeon ; verbatimDepth: 0.5–1 m; verbatimCoordinates: 34 ° 48 ' 36 " N 128 ° 41 ' 11 " E; Identification: identifiedBy: Shin, Chang & Lee; dateIdentified: 2024; Event: samplingProtocol: suction; eventDate: 13 / 07 / 2022; Record Level: basisOfRecord: PreservedSpecimen

Type status: Other material. Occurrence: individualCount: 1; sex: male; lifeStage: adult; preparations: mounted in glycerine on H-S slide; occurrenceID: 9DA22569-2898-59BD-A49B-63A0318CADAD; Taxon: scientificName: Anomalohalacarus angustus ; kingdom: Animalia; phylum: Arthropoda; class: Arachnida; order: Trombidiformes ; family: Halacaridae ; genus: Anomalohalacarus ; specificEpithet: angustus ; scientificNameAuthorship: Shin, Chang & Lee; Location: higherGeography: Northwest Pacific Ocean; continent: East Asia; country: Korea (the Republic of); countryCode: KR; stateProvince: Gyeongsangnam-do; municipality: Geoje-city; locality: Gujora Beach, Gujora-ri, Irun-myeon ; verbatimDepth: 0.5–1 m; verbatimCoordinates: 34 ° 48 ' 36 " N 128 ° 41 ' 11 " E; Identification: identifiedBy: Shin, Chang & Lee; dateIdentified: 2024; Event: samplingProtocol: suction; eventDate: 13 / 07 / 2022; Record Level: basisOfRecord: PreservedSpecimen

Type status: Other material. Occurrence: individualCount: 1; sex: male; lifeStage: adult; preparations: mounted in glycerine on H-S slide; occurrenceID: A32A825B-D46F-56A7-A5C3-E88285DD0DF5; Taxon: scientificName: Anomalohalacarus angustus ; kingdom: Animalia; phylum: Arthropoda; class: Arachnida; order: Trombidiformes ; family: Halacaridae ; genus: Anomalohalacarus ; specificEpithet: angustus ; scientificNameAuthorship: Shin, Chang & Lee; Location: higherGeography: Northwest Pacific Ocean; continent: East Asia; country: Korea (the Republic of); countryCode: KR; stateProvince: Gyeongsangnam-do; municipality: Geoje-city; locality: Gujora Beach, Gujora-ri, Irun-myeon ; verbatimDepth: 0.5–1 m; verbatimCoordinates: 34 ° 48 ' 36 " N 128 ° 41 ' 11 " E; Identification: identifiedBy: Shin, Chang & Lee; dateIdentified: 2024; Event: samplingProtocol: suction; eventDate: 13 / 07 / 2022; Record Level: basisOfRecord: PreservedSpecimen

Type status: Other material. Occurrence: individualCount: 1; sex: male; lifeStage: adult; preparations: mounted in glycerine on H-S slide; occurrenceID: EAE612B1-C053-538F-8B26-FD6DEA94B223; Taxon: scientificName: Anomalohalacarus angustus ; kingdom: Animalia; phylum: Arthropoda; class: Arachnida; order: Trombidiformes ; family: Halacaridae ; genus: Anomalohalacarus ; specificEpithet: angustus ; scientificNameAuthorship: Shin, Chang & Lee; Location: higherGeography: Northwest Pacific Ocean; continent: East Asia; country: Korea (the Republic of); countryCode: KR; stateProvince: Gyeongsangnam-do; municipality: Tongyeong-city; locality: Sulyug Beach, Sanyang-eup ; verbatimDepth: 0.5 m; verbatimCoordinates: 34 ° 49 ' 09 " N 128 ° 26 ' 22 " E; Identification: identifiedBy: Shin, Chang & Lee; dateIdentified: 2024; Event: samplingProtocol: suction; eventDate: 09 / 05 / 2024; Record Level: basisOfRecord: PreservedSpecimen

Type status: Other material. Occurrence: individualCount: 1; sex: male; lifeStage: adult; preparations: mounted in glycerine on H-S slide; occurrenceID: 2543AEC1-3283-5591-8D2B-705927077E24; Taxon: scientificName: Anomalohalacarus angustus ; kingdom: Animalia; phylum: Arthropoda; class: Arachnida; order: Trombidiformes ; family: Halacaridae ; genus: Anomalohalacarus ; specificEpithet: angustus ; scientificNameAuthorship: Shin, Chang & Lee; Location: higherGeography: Northwest Pacific Ocean; continent: East Asia; country: Korea (the Republic of); countryCode: KR; stateProvince: Gyeongsangnam-do; municipality: Tongyeong-city; locality: Sulyug Beach, Sanyang-eup ; verbatimDepth: 0.5 m; verbatimCoordinates: 34 ° 49 ' 09 " N 128 ° 26 ' 22 " E; Identification: identifiedBy: Shin, Chang & Lee; dateIdentified: 2024; Event: samplingProtocol: suction; eventDate: 09 / 05 / 2024; Record Level: basisOfRecord: PreservedSpecimen

Description

Female (holotype)

Idiosoma (Fig. 2 A) elongate, 364 µm long (360–372 µm, mean = 365 µm, n = 4), 103 µm wide (103–107 µm, mean = 105 µm, n = 4), length-to-width ratio about 3.52 (3.43–3.52, mean = 3.48, n = 4). Dorsal plates (AD and PD) with smooth surface, each plate clearly separated by membranous cuticle; OC absent. Membranous cuticle between AD and PD 71 % of idiosoma, covered with parallel wavy striae transversely; ornamented with 1 pair of glp (glp- 2) and three pairs of ds (ds- 2 – ds- 4); glp- 2 located at anterior third of idiosoma dorsolaterally.

AD (Fig. 2 A, C) 84 µm long (82–87 µm, mean = 84 µm, n = 4), about 0.23 times as long as idiosoma, 42 µm wide (40–44 µm, mean = 42 µm, n = 4), length-to-width ratio 1.98; rectangular-shaped with truncated anterior margin and slightly convex posterior margin; with 1 pair of glp- 1 and ds- 1; glp- 1 located at anterior 15 % of AD laterally.

PD (Fig. 2 A and D) undivided, smaller than AD, 0.74 times as long as AD, 0.52 times as wide as AD; 62 µm long (60–68 µm, mean = 63 µm, n = 4), about 0.17 times as long as idiosoma, 22 µm wide (22–26 µm, mean = 24 µm, n = 4), length-to-width ratio 2.79; elongate rectangular-shaped with convex anterior and blunt posterior margins; with a pair of ds- 6 and 2 pairs of glp (glp- 3 and glp- 4), each glp placed at anterior 14 % and 91 % of PD, respectively.

Five pairs of dorsal setae (Fig. 2 A): ds- 1 located at anterior 29 % of AD; 3 pairs of ds (ds- 2 – ds- 4) situated on membranous cuticle dorsolaterally, at anterior 16 %, 31 %, and 65 % of idiosoma, respectively; ds- 2 at level of posterior margin of AD; ds- 2 and ds- 4 slightly longer than others, similar to length of AD; ds- 5 absent; ds- 6 at posterior margin of PD.

All ventral plates (Fig. 2 B) small and separated by membranous cuticle with striae similar to those on dorsal surface of idiosoma, except between left and right plates of AE covered with smooth membranous cuticle. AE (Fig. 2 B and Fig. 4 A) 58 µm long (58–64 µm, mean = 60 µm, n = 4), about 0.16 times as long as idiosoma, 26 µm wide (26–29 µm, mean = 27 µm, n = 4), length-to-width ratio 2.20; divided into left and right plates by membranous cuticle without striae; distance between plates widest at 21 μm near insertion of leg I, narrowest at 12 μm near posterior ventral seta; each plate bearing 2 ventral, 1 lateral setae, and 1 epimeral pore; posterior ventral seta (0.5 times as long as AE) shorter than others (0.8 times as long as AE); epimeral pore inserted at anterior 61 % of AE.

PE (Fig. 2 B) 49 µm long (46–53 µm, mean = 50 µm, n = 4), about 0.13 times as long as idiosoma, 18 µm wide (17–20 µm, mean = 18 µm, n = 4), length-to-width ratio 2.76; located at anterior 68–81 % of idiosoma; divided into two plates, with 1 pair of dorsolateral setae and 2 pairs of ventral setae; foremost ventral seta located at anterior corner of PE and another seta at anterior 37 % of PE, respectively.

GP (Fig. 2 B and Fig. 4 B) divided into 3 plates, consisting of 1 pair of anterior genital plates and 1 posterior genital plate; anterior genital plates sub-rectangular, situated lateral to genital foramen, 17 µm long (16–19 µm, mean = 17 µm, n = 4), 9 µm wide (8–10 µm, mean = 9 µm, n = 4), length-to-width ratio of 1.96; posterior genital plate inverted triangular, between genital and anal foramina, 7 µm long (6–9 µm, mean = 7 µm, n = 4), 16 µm wide (13–20 µm, mean = 17 µm, n = 4), length-to-width ratio of 0.46; 3 pairs of pgs in genital area; foremost pgs situated on membranous cuticle anterior to genital foramen; 2 pairs of pgs on anterior genital plates. Genital foramen (Fig. 4 B) 19 µm long (17–21 µm, mean = 19 µm, n = 4), 4 µm wide (4–5 µm, mean = 4 µm, n = 4); slender, matchstick-shaped, pointed at anterior tip, widest at anterior 14 %; 1 pair of sgs at widest genital foramen; genital groove placed between posterior genital plate and anal sclerites. Ovipositor (Fig. 2 B) tube-shaped, its anterior tip not reaching anterior margin of PE.

Gnathosoma (Fig. 2 A and E) slender, 117 µm long (114–124 µm, mean = 118 µm, n = 4), about 0.32 times as long as idiosoma, 31 µm wide (30–33 µm, mean = 31 µm, n = 4), length-to-width ratio of 3.73; without areolae and costae on surface. Rostrum (Fig. 2 E) 62 µm long, as long as gnathosomal base, its tip not reaching to distal end of P- 2; 4 pairs of rostral setae, consisting of 2 pairs of short rostral setae (proto- and deutorostral setae) on distal tip of rostrum and 2 pairs of long rostral setae (trito- and basirostral setae) located at anterior 26 % and 59 % of ventral surface of rostrum, respectively. Palp (Fig. 2 F) with 4 segments, 11, 63, 8 and 16 µm, respectively; P- 1 trapezoid, without setae and spines; P- 2 longest, with 1 short proximal and 1 plumose distal setae dorsally, and distal seta slightly longer than proximal one; P- 3 shortest, with 1 cuticle spine dorsomedially; P- 4 conical, with 3 proximal and 1 tiny distal setae, and terminal tip bifurcated. Chelicera (Fig. 2 G) long, 113 µm long, consisting of basal segment and movable digit; basal segment, 99 µm long, with slender distal part (36 %) and broadened proximal part; movable digit, 16 µm long, with about 20 fine denticles along dorsal surface. Tectum (Fig. 2 A) very small, slightly protruding at middle of anterior margin.

All legs (Fig. 3 A – D) slender, legs I – IV 270, 168, 169, and 190 µm long, respectively; leg I longest and legs II – IV 0.62, 0.63, and 0.70 times as long as leg I, respectively. Chaetotaxy of legs as follows: trochanters 1-1 - 1 - 0; basifemora 2-2 - 1 - 0; telofemora 3-3 - 2 - 2; genua 5-5 - 3 - 3; tibiae 10-6 - 5 - 5; tarsi (excluding pas and famulus) 8-5 - 3 - 3; number of bipectinate setae on telofemora to tibiae I – IV (none in other segments): telofemora 0-0 - 0 - 1; genua 2-0 - 0 - 1; tibiae 2-2 - 2 - 3. Trochanters shortest in legs I – II. Basifemora shortest in legs III – IV; basifemur III with 1 long lateral seta, more than twice as long as corresponding segment. All genua shorter than preceding segment (telofemur), except for genu I similar in length to telofemur I. All tibiae longer than preceding segment (genu), except for tibiae I and II as long as preceding segment; tibia I with 2 bipectinate setae and 1 small spine ventromedially. All tarsi slightly shorter than preceding segment (tibia); tarsus I (Fig. 3 E) with 1 pair of fossary lamellae protruded distally; with 1 solenidion, 1 famulus, 3 dorsal, 4 ventral setae, and 1 pair of doublet eupathid pas; tarsus II (Fig. 3 F) with 1 slender claviform solenidion, 3 dorsal and 1 ventral setae, and 1 pair of singlet eupathid pas; tarsus III (Fig. 3 C) with 3 dorsal setae and 1 pair of pas consisting of 1 medial eupathid and 1 lateral filiform pas; tarsus IV (Fig. 3 D) with 3 dorsal setae and 1 pair of filiform pas; all tarsi with a pair of lateral claws bearing 1 dorsal accessory process and with single median claw; lateral claws of tarsus I shorter than others.

Male

Idiosoma (Fig. 4 C) 388 µm long (359–388 µm, mean = 372 µm, n = 5), 108 µm wide (102–137 µm, mean = 117 µm, n = 5), length-to-width ratio about 2.85–3.52; almost similar to female, except for length ratio of AD / PD and genital region. AD (Fig. 4 C and E) 74 µm long (69–85 µm, mean = 76 µm, n = 5), about 0.19 times as long as idiosoma, 37 µm wide (35–43 µm, mean = 39 µm, n = 5), length-to-width ratio 1.97. PD (Fig. 4 C and F) undivided, rectangular-shaped with both blunt anterior and posterior margins, almost similar to length of AD (0.96 times as long as AD), more slender 0.65 times as wide as AD; 72 µm long (68–83 µm, mean = 74 µm, n = 5), about 0.19 times as long as idiosoma, 18 µm wide (17–21 µm, mean = 19 µm, n = 5), length-to-width ratio 4.00.

GA (Fig. 4 D and G) 58 µm long (52–58 µm, mean = 55 µm, n = 5), about 0.15 times as long as idiosoma, 40 µm wide (36–40 µm, mean = 38 µm, n = 5), length-to-width ratio 1.45; elliptical, with concave posterior region between GO and anal plate and gradually tapering to pointed ends at both sides posteriorly; with 7 pairs of pgs, each forming several branches towards distal part of seta. GO 19 µm long, (15–19 µm, mean = 17 µm, n = 5), 15 µm wide (12–15 µm, mean = 14 µm, n = 5), located in center of GA, about 0.33 times as long as GA; with 2 pairs of sgs, each located at anterior 45 % and 74 % of genital sclerites. Spermatocyte (Fig. 4 D) distinct, extending beyond anterior end of PE.

Diagnosis

Idiosoma sub-conical, 363–372 µm long in females and 359–388 µm long in males; membranous cuticle decorated with wavy striae, except between divided AE plates; PD undivided, much more slender than AD; 5 pairs of dorsal setae (lacking ds- 5); AE divided into two plates by smooth membranous cuticle; PE with 1 dorsal and 2 ventral setae; P- 2 with 1 short proximal and 1 plumose distal setae, dorsally; genua I and IV with 2 and 1 ventral bipectinate setae, respectively; tibia IV with 5 setae; tarsus I with 4 ventral setae; female's GP divided into three plates; female with 1 pair of sgs on genital foramen; male's GA with 7 pairs of branched pgs and 2 pairs of sgs.

Etymology

The specific name is derived from the Latin ‘ angustus ’ (meaning narrow or slender), alluding to a slender posterior dorsal plate in the new species.

Distribution

South Korea (this study).

Co-occurrence

Anomalohalacarus angustus sp. nov. was found among particles of various sizes, ranging from fine to coarse sandy beaches, at Pohang on the east coast and Geoje and Tongyeong on the south coast. On the fine sandy beach at Pohang, Actacarus ornatus and Actacarus pacificus co-occurred with the new species and on the coarse sandy beaches of Geoje and Tongyeong, Acarochelopodia sp. , Actacarus ornatus , Actacarus pacificus , and Maracarus sp. also were present. Harpacticoids, nematodes, polychaetes, and ostracods were observed along with halacarids.

Figures

Figure 2. Anomalohalcarus angustus sp. nov., female (MABIK CR 00257793). A Idiosoma, dorsal; B Idiosoma, ventral; C AD, dorsal; D PD, dorsal; E Gnathosoma, ventral; F Palp, lateral; G Chelicerae, lateral.

Figure 3. Anomalohalcarus angustus sp. nov., female (MABIK CR 00257793). A – D Legs I – IV, ventromedial; E Tip of tarsus I, lateral; F Tip of tarsus II, lateral.

Figure 4. Anomalohalcarus angustus sp. nov. A, B, Female (MABIK CR 00257793). A AE, ventral; B GP, ventral. C – G, Male (MABIK CR 00257794). C Idiosoma, dorsal; D Idiosoma, ventral; E AD, dorsal; F PD, dorsal; G GA, with branched pgs and sgs.