Stylicletodes trifidus Cho, Kim & Lee, 2022

Cho, Kyuhee, Kim, Jong Guk & Lee, Jimin, 2022, A new species of the genus Stylicletodes Lang, 1936 (Copepoda, Harpacticoida, Cletodidae) from South Korea, Biodiversity Data Journal 10, pp. 90590-90590 : 90590

Stylicletodes trifidus Cho, Kim & Lee sp. n.

Stylicletodes Lang, 1936

Stylicletodes trifidus Stylicletodes longicaudatus

Materials

Type status: Holotype. Occurrence: individualCount: 1; sex: female; lifeStage: adult; preparations: preserved in 95% ethanol; occurrenceID: 7790343C-DDD5-54FE-897F-B6B002B5DBAD; Taxon: kingdom: Animalia; phylum: Arthropoda; class: Copepoda; order: Harpacticoida; family: Cletodidae; genus: Stylicletodes; specificEpithet: trifidus; taxonRank: species; scientificNameAuthorship: Cho, Kim & Lee; Location: higherGeography: East Asia; waterBody: Yellow sea; country: Korea; countryCode: KR; verbatimDepth: 77.2 m; locationRemarks: stn 37-8; verbatimLatitude: 36°58'24.66"N; verbatimLongitude: 123°48'39.72"E; decimalLatitude: 36.97351667; decimalLongitude: 123.81103333; Identification: identifiedBy: Cho, Kim & Lee; dateIdentified: 2022; Event: samplingProtocol: Smith-McIntyre grab; eventDate: 24/04/2019; Record Level: institutionID: MABIK CR00252667; institutionCode: Marine Biodiversity Institute of Korea (MABIK); basisOfRecord: PreservedSpecimen Type status: Paratype. Occurrence: individualCount: 1; sex: male; lifeStage: adult; preparations: dissected on 4 slides; occurrenceID: 8984821E-EBCE-51F6-9C49-DB90C0947C58; Taxon: kingdom: Animalia; phylum: Arthropoda; class: Copepoda; order: Harpacticoida; family: Cletodidae; genus: Stylicletodes; specificEpithet: trifidus; taxonRank: species; scientificNameAuthorship: Cho, Kim & Lee; Location: higherGeography: East Asia; waterBody: Yellow sea; country: Korea; countryCode: KR; verbatimDepth: 77.2 m; locationRemarks: stn 37-8; verbatimLatitude: 36°58'24.66"N; verbatimLongitude: 123°48'39.72"E; decimalLatitude: 36.97351667; decimalLongitude: 123.81103333; Identification: identifiedBy: Cho, Kim & Lee; dateIdentified: 2022; Event: samplingProtocol: Smith-McIntyre grab; eventDate: 24/04/2019; Record Level: institutionID: MABIK CR00252670; institutionCode: Marine Biodiversity Institute of Korea (MABIK); basisOfRecord: PreservedSpecimen Type status: Paratype. Occurrence: individualCount: 1; sex: female; lifeStage: adult; preparations: dissected on 11 slides; occurrenceID: 2CD9F77A-1962-5EAA-BA24-4EA8D8C9955D; Taxon: kingdom: Animalia; phylum: Arthropoda; class: Copepoda; order: Harpacticoida; family: Cletodidae; genus: Stylicletodes; specificEpithet: trifidus; taxonRank: species; scientificNameAuthorship: Cho, Kim & Lee; Location: higherGeography: East Asia; waterBody: Yellow sea; country: Korea; countryCode: KR; verbatimDepth: 77.2 m; locationRemarks: stn 37-8; verbatimLatitude: 36°58'24.66"N; verbatimLongitude: 123°48'39.72"E; decimalLatitude: 36.97351667; decimalLongitude: 123.81103333; Identification: identifiedBy: Cho, Kim & Lee; dateIdentified: 2022; Event: samplingProtocol: Smith-McIntyre grab; eventDate: 24/04/2019; Record Level: institutionID: MABIK CR00252669; institutionCode: Marine Biodiversity Institute of Korea (MABIK); basisOfRecord: PreservedSpecimen Type status: Paratype. Occurrence: individualCount: 1; sex: male; lifeStage: adult; preparations: preserved in 95% ethanol; occurrenceID: 60FF350A-DDD9-551D-ADB0-06FF 2AD 80EF2; Taxon: kingdom: Animalia; phylum: Arthropoda; class: Copepoda; order: Harpacticoida; family: Cletodidae; genus: Stylicletodes; specificEpithet: trifidus; taxonRank: species; scientificNameAuthorship: Cho, Kim & Lee; Location: higherGeography: East Asia; waterBody: Yellow sea; country: Korea; countryCode: KR; verbatimDepth: 77.2 m; locationRemarks: stn 37-8; verbatimLatitude: 36°58'24.66"N; verbatimLongitude: 123°48'39.72"E; decimalLatitude: 36.97351667; decimalLongitude: 123.81103333; Identification: identifiedBy: Cho, Kim & Lee; dateIdentified: 2022; Event: samplingProtocol: Smith-McIntyre grab; eventDate: 24/04/2019; Record Level: institutionID: MABIK CR00252668; institutionCode: Marine Biodiversity Institute of Korea (MABIK); basisOfRecord: PreservedSpecimen Type status: Paratype. Occurrence : individualCount: 1; sex: female; lifeStage: adult; preparations: dissected on 3 slides; occurrenceID: DE8EB9F0-2FD1-5FA0-9779-7A3A6F2FD586; Taxon : kingdom: Animalia ; phylum: Arthropoda ; class: Copepoda ; order: Harpacticoida ; family: Cletodidae ; genus: Stylicletodes ; specificEpithet: trifidus; taxonRank: species; scientificNameAuthorship: Cho , Kim & Lee; Location: higherGeography: East Asia; waterBody: Yellow sea; country: Korea; countryCode: KR; verbatimDepth: 77.2 m; locationRemarks: stn 37-8; verbatimLatitude: 36°58'24.66"N; verbatimLongitude: 123°48'39.72"E; decimalLatitude: 36.97351667; decimalLongitude: 123.81103333; Identification: identifiedBy: Cho, Kim & Lee; dateIdentified: 2022; Event: samplingProtocol: Smith-McIntyre grab; eventDate: 24/04/2019; Record Level: basisOfRecord: PreservedSpecimen Type status: Paratype. Occurrence : individualCount: 3; sex: male; lifeStage: adult; preparations: dissected each on 3 slides; occurrenceID: E3AA6628-F9BC-5586-A548-61E148410951; Taxon : kingdom: Animalia ; phylum: Arthropoda ; class: Copepoda ; order: Harpacticoida ; family: Cletodidae ; genus: Stylicletodes ; specificEpithet: trifidus; taxonRank: species; scientificNameAuthorship: Cho , Kim & Lee; Location: higherGeography: East Asia; waterBody: Yellow sea; country: Korea; countryCode: KR; verbatimDepth: 77.2 m; locationRemarks: stn 37-8; verbatimLatitude: 36°58'24.66"N; verbatimLongitude: 123°48'39.72"E; decimalLatitude: 36.97351667; decimalLongitude: 123.81103333; Identification: identifiedBy: Cho, Kim & Lee; dateIdentified: 2022; Event: samplingProtocol: Smith-McIntyre grab; eventDate: 24/04/2019; Record Level: basisOfRecord: PreservedSpecimen Type status: Other material. Occurrence : individualCount: 1; sex: female; lifeStage: adult; preparations: dissected on 3 slides; occurrenceID: 1ED7806C-E517-54D0-A0AE-08DC1B6AA73A; Taxon : kingdom: Animalia ; phylum: Arthropoda ; class: Copepoda ; order: Harpacticoida ; family: Cletodidae ; genus: Stylicletodes ; specificEpithet: trifidus; taxonRank: species; scientificNameAuthorship: Cho , Kim & Lee; Location: higherGeography: East Asia; waterBody: Yellow sea; country: Korea; countryCode: KR; verbatimDepth: 88.2 m; locationRemarks: stn 35-7 #2; verbatimLatitude: 34°59'51.00"N; verbatimLongitude: 125°00'04.2"E; decimalLatitude: 34.9975; decimalLongitude: 125.00116667; Identification: identifiedBy: Cho, Kim & Lee; dateIdentified: 2022; Event: samplingProtocol: Smith-McIntyre grab; eventDate: 29/08/2020; Record Level: basisOfRecord: PreservedSpecimen Type status: Other material. Occurrence : individualCount: 1; sex: male; lifeStage: adult; preparations: preserved in 95% ethanol; occurrenceID: FA0771F8-1D46-5620-849F-40976B6E7E87; Taxon : kingdom: Animalia ; phylum: Arthropoda ; class: Copepoda ; order: Harpacticoida ; family: Cletodidae ; genus: Stylicletodes ; specificEpithet: trifidus; taxonRank: species; scientificNameAuthorship: Cho , Kim & Lee; Location: higherGeography: East Asia; waterBody: Yellow sea; country: Korea; countryCode: KR; verbatimDepth: 88.2 m; locationRemarks: stn 35-7 #2; verbatimLatitude: 34°59'51.00"N; verbatimLongitude: 125°00'04.2"E; decimalLatitude: 34.9975; decimalLongitude: 125.00116667; Identification: identifiedBy: Cho, Kim & Lee; dateIdentified: 2022; Event: samplingProtocol: Smith-McIntyre grab; eventDate: 29/08/2020; Record Level: institutionID: MInRB-Hr86-L001; institutionCode: Marine Interstitial fauna Resources Bank; basisOfRecord: PreservedSpecimen Type status: Other material. Occurrence : individualCount: 1; sex: female; lifeStage: adult; preparations: preserved in 95% ethanol; occurrenceID: 254CB7CE-2CC4-5A76-A1B8-0018CA2FC96D; Taxon : kingdom: Animalia ; phylum: Arthropoda ; class: Copepoda ; order: Harpacticoida ; family: Cletodidae ; genus: Stylicletodes ; specificEpithet: trifidus; taxonRank: species; scientificNameAuthorship: Cho , Kim & Lee; Location: higherGeography: East Asia; waterBody: Yellow sea; country: Korea; countryCode: KR; verbatimDepth: 88.0 m; locationRemarks: stn 35-7 #1; verbatimLatitude: 34°59'40.14"N; verbatimLongitude: 125°00'2.82"E; decimalLatitude: 34.99448333; decimalLongitude: 125.00078333; Identification: identifiedBy: Cho, Kim & Lee; dateIdentified: 2022; Event: samplingProtocol: Smith-McIntyre grab; eventDate: 20/04/2019; Record Level: institutionID: MInRB-Hr86-L002; institutionCode: Marine Interstitial fauna Resources Bank; basisOfRecord: PreservedSpecimen Type status: Other material. Occurrence : individualCount: 1; sex: female; lifeStage: adult; preparations: dissected on 6 slides; occurrenceID: CD6754DF-B256-54AB-B7B6-B1940B774B54; Taxon : kingdom: Animalia ; phylum: Arthropoda ; class: Copepoda ; order: Harpacticoida ; family: Cletodidae ; genus: Stylicletodes ; specificEpithet: trifidus; taxonRank: species; scientificNameAuthorship: Cho , Kim & Lee; Location: higherGeography: East Asia; waterBody: Yellow sea; country: Korea; countryCode: KR; verbatimDepth: 91.3 m; locationRemarks: stn 35-9; verbatimLatitude: 34°59'50.04"N; verbatimLongitude: 124°30'0.36"E; decimalLatitude: 34.99723333; decimalLongitude: 124.5001; Identification: identifiedBy: Cho, Kim & Lee; dateIdentified: 2022; Event: samplingProtocol: Smith-McIntyre grab; eventDate: 20/04/2019; Record Level: basisOfRecord: PreservedSpecimen Type status: Other material. Occurrence : individualCount: 1; sex: female; lifeStage: adult; preparations: dissected on 3 slides; occurrenceID: 64AF298A-7151-5F08-8155-73F4B6494798; Taxon : kingdom: Animalia ; phylum: Arthropoda ; class: Copepoda ; order: Harpacticoida ; family: Cletodidae ; genus: Stylicletodes ; specificEpithet: trifidus; taxonRank: species; scientificNameAuthorship: Cho , Kim & Lee; Location: higherGeography: East Asia; waterBody: Yellow sea; country: Korea; countryCode: KR; verbatimDepth: 77.2 m; locationRemarks: stn 35-13; verbatimLatitude: 35°00'06.36"N; verbatimLongitude: 123°30'02.10"E; decimalLatitude: 35.00176667; decimalLongitude: 123.50058333; Identification: identifiedBy: Cho, Kim & Lee; dateIdentified: 2022; Event: samplingProtocol: Smith-McIntyre grab; eventDate: 17/10/2018; Record Level: basisOfRecord: PreservedSpecimen Type status: Other material. Occurrence : individualCount: 2; sex: female; lifeStage: adult; preparations: preserved in 95% ethanol; occurrenceID: 8C55C5E0-A228-559D-8DA6-3DB85121E6CC; Taxon : kingdom: Animalia ; phylum: Arthropoda ; class: Copepoda ; order: Harpacticoida ; family: Cletodidae ; genus: Stylicletodes ; specificEpithet: trifidus; taxonRank: species; scientificNameAuthorship: Cho , Kim & Lee; Location: higherGeography: East Asia; waterBody: Southern Sea of Korea; country: Korea; countryCode: KR; verbatimDepth: 105.8 m; locationRemarks: stn A3; verbatimLatitude: 34°25'25.01"N; verbatimLongitude: 128°29'59.34"E; decimalLatitude: 34.87361389; decimalLongitude: 128.49981667; Identification: identifiedBy: Cho, Kim & Lee; dateIdentified: 2022; Event: samplingProtocol: Smith-McIntyre grab; eventDate: 08/06/2015; Record Level: institutionID: MInRB-Hr86-L003; institutionCode: Marine Interstitial fauna Resources Bank; basisOfRecord: PreservedSpecimen Type status: Other material. Occurrence : individualCount: 1; sex: male; lifeStage: adult; preparations: preserved in 95% ethanol; occurrenceID: 543CF137-07D0-5CBC-8359- 580AD 73D62C2; Taxon : kingdom: Animalia ; phylum: Arthropoda ; class: Copepoda ; order: Harpacticoida ; family: Cletodidae ; genus: Stylicletodes ; specificEpithet: trifidus; taxonRank: species; scientificNameAuthorship: Cho , Kim & Lee; Location: higherGeography: East Asia; waterBody: Southern Sea of Korea; country: Korea; countryCode: KR; verbatimDepth: 105.8 m; locationRemarks: stn A3; verbatimLatitude: 34°25'25.01"N; verbatimLongitude: 128°29'59.34"E; decimalLatitude: 34.87361389; decimalLongitude: 128.49981667; Identification: identifiedBy: Cho, Kim & Lee; dateIdentified: 2022; Event: samplingProtocol: Smith-McIntyre grab; eventDate: 08/06/2015; Record Level: institutionID: MInRB-Hr86-L003; institutionCode: Marine Interstitial fauna Resources Bank; basisOfRecord: PreservedSpecimen Type status: Other material. Occurrence : individualCount: 3; sex: female; lifeStage: adult; preparations: dissected each on 3 slides; occurrenceID: 69D4DDFD-1995-5D4F-AB95-366C2AC433CB; Taxon : kingdom: Animalia ; phylum: Arthropoda ; class: Copepoda ; order: Harpacticoida ; family: Cletodidae ; genus: Stylicletodes ; specificEpithet: trifidus; taxonRank: species; scientificNameAuthorship: Cho , Kim & Lee; Location: higherGeography: East Asia; waterBody: Southern Sea of Korea; country: Korea; countryCode: KR; verbatimDepth: 56.7 m; locationRemarks: stn B3; verbatimLatitude: 34˚04'78.41"N; verbatimLongitude: 127˚30'03.13"E; decimalLatitude: 34.08844722; decimalLongitude: 127.50086944; Identification: identifiedBy: Cho, Kim & Lee; dateIdentified: 2022; Event: samplingProtocol: Smith-McIntyre grab; eventDate: 23/04/2017; Record Level: basisOfRecord: PreservedSpecimen Type status: Other material. Occurrence : individualCount: 1; sex: female; lifeStage: adult; preparations: undissected on one slides; occurrenceID: 6F688BC6-EAFE-5A16-BDEA-1E2A318A271F; Taxon : kingdom: Animalia ; phylum: Arthropoda ; class: Copepoda ; order: Harpacticoida ; family: Cletodidae ; genus: Stylicletodes ; specificEpithet: trifidus; taxonRank: species; scientificNameAuthorship: Cho , Kim & Lee; Location: higherGeography: East Asia; waterBody: Southern Sea of Korea; country: Korea; countryCode: KR; verbatimDepth: 80.7 m; locationRemarks: stn B4 #1; verbatimLatitude: 33˚59'53.04"N; verbatimLongitude: 127˚29'27.60"E; decimalLatitude: 33.99806667; decimalLongitude: 127.491; Identification: identifiedBy: Cho, Kim & Lee; dateIdentified: 2022; Event: samplingProtocol: Smith-McIntyre grab; eventDate: 08/06/2015; Record Level: basisOfRecord: PreservedSpecimen Type status: Other material. Occurrence : individualCount: 1; sex: male; lifeStage: adult; preparations: undissected on one slides; occurrenceID: 016028BE-DD62-5D66-B893-A6B961949873; Taxon : kingdom: Animalia ; phylum: Arthropoda ; class: Copepoda ; order: Harpacticoida ; family: Cletodidae ; genus: Stylicletodes ; specificEpithet: trifidus; taxonRank: species; scientificNameAuthorship: Cho , Kim & Lee; Location: higherGeography: East Asia; waterBody: Southern Sea of Korea; country: Korea; countryCode: KR; verbatimDepth: 80.7 m; locationRemarks: stn B4 #1; verbatimLatitude: 33˚59'53.04"N; verbatimLongitude: 127˚29'27.60"E; decimalLatitude: 33.99806667; decimalLongitude: 127.491; Identification: identifiedBy: Cho, Kim & Lee; dateIdentified: 2022; Event: samplingProtocol: Smith-McIntyre grab; eventDate: 08/06/2015; Record Level: basisOfRecord: PreservedSpecimen Type status: Other material. Occurrence : individualCount: 1; sex: male; lifeStage: adult; preparations: dissected on 3 slides; occurrenceID: 60111326-6851-5182-B67E-A393DFFE0C50; Taxon : kingdom: Animalia ; phylum: Arthropoda ; class: Copepoda ; order: Harpacticoida ; family: Cletodidae ; genus: Stylicletodes ; specificEpithet: trifidus; taxonRank: species; scientificNameAuthorship: Cho , Kim & Lee; Location: higherGeography: East Asia; waterBody: Southern Sea of Korea; country: Korea; countryCode: KR; verbatimDepth: 80.7 m; locationRemarks: stn B4 #1; verbatimLatitude: 33˚59'53.04"N; verbatimLongitude: 127˚29'27.60"E; decimalLatitude: 33.99806667; decimalLongitude: 127.491; Identification: identifiedBy: Cho, Kim & Lee; dateIdentified: 2022; Event: samplingProtocol: Smith-McIntyre grab; eventDate: 08/06/2015; Record Level: basisOfRecord: PreservedSpecimen Type status: Other material. Occurrence : individualCount: 2; sex: female; lifeStage: adult; preparations: preserved in 95% ethanol; occurrenceID: 0AF0451A-1D92-5B4B-ABA1-68448200C3F1; Taxon : kingdom: Animalia ; phylum: Arthropoda ; class: Copepoda ; order: Harpacticoida ; family: Cletodidae ; genus: Stylicletodes ; specificEpithet: trifidus; taxonRank: species; scientificNameAuthorship: Cho , Kim & Lee; Location: higherGeography: East Asia; waterBody: Southern Sea of Korea; country: Korea; countryCode: KR; verbatimDepth: 80.7 m; locationRemarks: stn B4 #1; verbatimLatitude: 33˚59'53.04"N; verbatimLongitude: 127˚29'27.60"E; decimalLatitude: 33.99806667; decimalLongitude: 127.491; Identification: identifiedBy: Cho, Kim & Lee; dateIdentified: 2022; Event: samplingProtocol: Smith-McIntyre grab; eventDate: 08/06/2015; Record Level: institutionID: MInRB-Hr86-L004; institutionCode: Marine Interstitial fauna Resources Bank; basisOfRecord: PreservedSpecimen Type status: Other material. Occurrence : individualCount: 4; sex: male; lifeStage: adult; preparations: preserved in 95% ethanol; occurrenceID: 757A85E8-C163-52CB-9F9A-9F35535BD59C; Taxon : kingdom: Animalia ; phylum: Arthropoda ; class: Copepoda ; order: Harpacticoida ; family: Cletodidae ; genus: Stylicletodes ; specificEpithet: trifidus; taxonRank: species; scientificNameAuthorship: Cho , Kim & Lee; Location: higherGeography: East Asia; waterBody: Southern Sea of Korea; country: Korea; countryCode: KR; verbatimDepth: 80.7 m; locationRemarks: stn B4 #1; verbatimLatitude: 33˚59'53.04"N; verbatimLongitude: 127˚29'27.60"E; decimalLatitude: 33.99806667; decimalLongitude: 127.491; Identification: identifiedBy: Cho, Kim & Lee; dateIdentified: 2022; Event: samplingProtocol: Smith-McIntyre grab; eventDate: 08/06/2015; Record Level: institutionID: MInRB-Hr86-L004; institutionCode: Marine Interstitial fauna Resources Bank; basisOfRecord: PreservedSpecimen Type status: Other material. Occurrence : individualCount: 1; sex: male; lifeStage: adult; preparations: dissected on 3 slides; occurrenceID: 4AA5AF24-DC37-5F71-B0DE-B10D1F7F6053; Taxon : kingdom: Animalia ; phylum: Arthropoda ; class: Copepoda ; order: Harpacticoida ; family: Cletodidae ; genus: Stylicletodes ; specificEpithet: trifidus; taxonRank: species; scientificNameAuthorship: Cho , Kim & Lee; Location: higherGeography: East Asia; waterBody: Southern Sea of Korea; country: Korea; countryCode: KR; verbatimDepth: 78.7 m; locationRemarks: stn B4 #3; verbatimLatitude: 33˚59'52.62"N; verbatimLongitude: 127˚29'58.20"E; decimalLatitude: 33.99795; decimalLongitude: 127.4995; Identification: identifiedBy: Cho, Kim & Lee; dateIdentified: 2022; Event: samplingProtocol: Smith-McIntyre grab; eventDate: 26/04/2016; Record Level: basisOfRecord: PreservedSpecimen Type status: Other material. Occurrence : individualCount: 2; sex: male; lifeStage: adult; preparations: preserved in 95% ethanol; occurrenceID: 6556F4AB-08CC-5649-90F4-201E34C014CF; Taxon : kingdom: Animalia ; phylum: Arthropoda ; class: Copepoda ; order: Harpacticoida ; family: Cletodidae ; genus: Stylicletodes ; specificEpithet: trifidus; taxonRank: species; scientificNameAuthorship: Cho , Kim & Lee; Location: higherGeography: East Asia; waterBody: Southern Sea of Korea; country: Korea; countryCode: KR; verbatimDepth: 78.7 m; locationRemarks: stn B4 #3; verbatimLatitude: 33˚59'52.62"N; verbatimLongitude: 127˚29'58.20"E; decimalLatitude: 33.99795; decimalLongitude: 127.4995; Identification: identifiedBy: Cho, Kim & Lee; dateIdentified: 2022; Event: samplingProtocol: Smith-McIntyre grab; eventDate: 26/04/2016; Record Level: institutionID: MInRB-Hr86-L005; institutionCode: Marine Interstitial fauna Resources Bank; basisOfRecord: PreservedSpecimen

Description

Female (based on the paratype, MABIK CR00252669): Body length 484 μm (ranging from 411-500 μm, mean = 461 μm, n= 11; holotype 457 μm). Habitus (Fig. 2 A-B) cylindrical, gradually narrowing posteriorly, with unclear separation between prosome and urosome. Integument strongly chitinized, with fine, thread-like setular ornamentation, except for cephalic shield and anal somite. Prosome (Fig. 2 A-B) slightly shorter than urosome, 4-segmented, comprising cephalothorax and three free pedigerous somites. Cephalothorax representing approximately 1/5 of body length, maximum width at level of posterior 2/3, with 1 pair of lateral tube pores and several pairs of sensilla; posterior margin ornamented with fine setules and with 4 pairs of sensillum-bearing socles; lateral margin with fine setules. Dorsal surface of free pedigerous somites covered with fine setules posteriorly, with 1 mid-dorsal tube pore and 1-2 pairs of lateral tube pores; posterior margins with fine setules and 2-4 sensillum-bearing socles.

Urosome (Fig. 2 A-B and Fig. 3 A-C) 5-segmented, comprising P5-bearing somite, genital double-somite, and 3 free abdominal somites; posterior margins, except for anal somite, as in prosome, but lacking mid-dorsal tube pore. Genital somite and third urosomite separated dorsally and laterally, but completely fused ventrally forming genital double-somite (Fig. 3 A-C). Genital aperture (Fig. 3 C and Fig. 8 B) located at anterior half, fused medially forming a transverse slit; covered by a single plate with 3 setae representing vestigial P6 (Fig. 8 B), of which innermost seta longest. Copulatory pore (Fig. 3 C) located at anterior 2/3 of genital double-somite. Anal somite (Fig. 3 A-C) 1.3 times longer than wide, laterally constricted at mid-length; with 3 pairs of tube pores proximally, and both subdistally in dorsal and ventral surface, respectively; ornamented with spinules laterally and ventrally along posterior border; anal opening (Fig. 3 A-B) large, ornamented with long setules; anal operculum semicircular and wide, located at anterior 1/3 of anal somite, with 2 sensillum-bearing socles and 2 rows of minute dorsal spinules.

Caudal rami (Fig. 2 A-B and Fig. 3 A-C) distinctly divergent, cylindrical, extremely elongate, as long as three abdominal urosomites combined, L/W ratio 12.7, as long as 1/4 of body length; with few spinules at posterior margin of ramus ventrally (Fig. 3 C); with 7 setae: lateral setae I and II inserted in proximal 1/8 of ramus, seta II about twice as long as seta I; seta III shortest, arising from outer distal corner; terminal seta IV fused basally to well-developed seta V, as long as seta II; terminal seta V longest, slightly shorter than ramus; seta VI short, slightly longer than seta III, located at inner distal corner; tri-articulate seta VII arising from minute dorsal pedestal, located in middle of caudal ramus.

Rostrum (Fig. 2 A, C and Fig. 5 B) fused to cephalic shield, reaching beyond first antennular segment; with trifid tip, with 1 pair of subapical sensilla and 1 ventral tube pore (Fig. 5 B).

Antennule (Fig. 4 A) 5-segmented. First segment short, with 3 rows of inner spinules. Second segment with small, blunt process on outer margin. Third segment longest, with 1 seta fused basally to aesthetasc on distal peduncle. Fourth segment shortest. Distal segment with 5 bi-articulate outer setae; with apical acrothek composed of 1 aesthetasc and 2 long setae. Armature formula 1-[1], 2-[5], 3-[5 + (1 + ae)], 4-[1], 5-[9 + acrothek)].

Antenna (Fig. 4 B). Coxa (not figured) small. Allobasis with 2 unipinnate setae and 1 group of spinules on abexopodal margin. Exopod 1-segmented, small, with 1 uniplumose and 1 pinnate seta. Free endopod ornamented with spinules along both inner and outer and subdistal margins; lateral armature composed of 2 bare spines and distal armature consisting of 1 bare, 1 weakly pinnate, and 3 pinnate spines.

Mandible (Fig. 4 C). Coxa slender; gnathobase with 1 unicuspidate and 2 bicuspidate teeth and 1 bare seta (fused to coxa basally). Palp very reduced, represented by 2 naked slender setae fused at base.

Maxillule (Fig. 4 D). Praecoxal arthrite strongly developed, with 2 juxtaposed bare setae on anterior surface and 6 elements around distal margin; with 1 row of posterior spinules. Coxa with 1 outer row of long spinules; endite with 1 stout plumose spine. Basis apically with 1 stout plumose spine and 2 bare setae. Endopod represented by 2 bare setae.

Maxilla (Fig. 4 E). Syncoxa with 2 outer groups of strong spinules and 1 inner group of minute spinules; with 2 endites: proximal endite small, apically with 1 bare seta; distal endite longer than preceding one, with 1 stout comb-like seta and 2 bare setae. Allobasis apically with 1 stout comb-like seta and 1 slender seta. Endopod represented by 2 bare setae.

Maxilliped absent, with a small plate in the place where this appendage was supposed to be (see asterisk in Fig. 5 A-B).

P1-P4 (Fig. 6 A-B and Fig. 7 A-B) with very wide and narrow intercoxal sclerites, without ornamentation; with 3-segmented exopods and 2-segmented endopods.

P1 (Fig. 6 A). Praecoxa large, without ornamentation. Coxa with 1 anterior row of long spinules. Basis ornamented with 1 outer and 1 inner row of spinules, one additional spinular row between rami, and 1 tube pore anteriorly; with 1 long pinnate outer seta and 1 stout pinnate inner spine. Exopod longer than endopod; each segment ornamented with outer spinules and inner setules; exp-1 and exp-2 each with 1 unispinulose outer spine; exp-2 smallest; exp-3 longest with 2 unispinulose outer spines and 2 unispinulose apical setae; inner apical seta about twice as long as outer one. Endopod reaching tip of exp-2; enp-1 very small, without ornamentation and armature; enp-2 elongate, about 5 times longer than enp-1, with rows of long inner setules and thin outer spinules, 1 subdistal inner spinule, and 2 long plumose apical setae; outer apical seta ornamented with outer spinules, slightly shorter than inner one.

P2-P4 (Fig. 6 B and Fig. 7 A-B). Coxae and bases ornamented with anterior spinular rows; anterior surface of coxae proximally with a slight depression, strongly sclerotized. Bases weakly prolonged, with 1 pinnate outer spine and 1 anterior tube pore. Exopods longer than endopods; each segment ornamented with outer and inner spinules as figured; exp-2 shortest, exp-3 longest; exp-1 and exp-2 each with 1 unispinulose outer spine; exp-3 with 2 unispinulose outer spines and 2 unispinulose apical setae. Endopods slightly longer than exp-1 and exp-2 combined in P2, as long as exp-1 and exp-2 combined in P3, and as long as exp-1 in P4; all enp-1 without ornamentation and armature; enp-2 ornamented with outer and inner setules and a few inner spinules; P2-P3 enp-2 and P4 enp-2 about 5 and 4 times longer than enp-1, respectively; enp-2 apically with 1 pinnate (in P2) or spiniform (in P3-P4) outer seta and 1 plumose inner seta; each inner seta about 2 (P2) and 3 (P3-P4) times longer than outer seta, respectively.

Armature formula of P1-P4 shown in Table 2 .

P5 (Fig. 8 A) consisting of baseoendopod and 1-segmented exopod. Baseoendopod with a few spinules and 1 long anterior tube pore arising from long protuberance (indicated by arrowhead in Fig. 8 A); outer setophore very long, ornamented with long lateral setules, with 1 bare seta, shorter than setophore; endopodal lobe elongate, reaching middle of exopod, ornamented with anterior and lateral spinules, with 2 spiniform setae and 1 long tube pore on inner margin, and 1 bare and 1 spiniform seta on distal margin. Exopod extremely elongate, covered with anterior spinules; outer margin ornamented with spinules, with 3 densely plumose setae; inner margin ornamented with long setules proximally and minute spinules subdistally, with 1 small pinnate spine and 1 long tube pore subdistally (indicated by arrowhead in Fig. 8 A); apical margin with 1 long spine ornamented with setules proximally and spinules subdistally.

Male (based on the paratype, MABIK CR00252670): Body (Fig. 2 D) slightly smaller than female, 448 μm long (ranging from 401-475 μm, mean = 443 μm, n = 8). Sexual dimorphism in urosomal segmentation, relative length of caudal setae, antennule, P3, P5, and P6.

Urosome (Fig. 2 D and Fig. 9 C) 6-segmented, genital and first abdominal somites completely separate. First abdominal somite with 1 row of ventral spinules.

Caudal rami (Fig. 9 C, D) as in female, except for seta V longer than caudal ramus.

Antennule (Fig. 9 A, B) 6-segmented, chirocer, with geniculation between fifth and sixth segments; with aesthetasc on fifth and sixth segments; first segment with 4 rows of inner spinules; fourth segment very small (difficult to see); fifth segment markedly swollen, with 1 anterior patch of minute spinules; sixth segment conical, slightly curved inwards. Armature formula as follows: 1-[1], 2-[7], 3-[5], 4-[2], 5-[8 + (1 + ae)], 6-[9 + acrothek].

P3 (Fig. 10 A). Exopod as in female; endopod 2-segmented, as in female, except for outer spine of enp-2 (indicated with an arrowhead in Fig. 10 A) fused to segment forming an apophysis pinnated subdistally.

P5 (Fig. 10 B) similar to female in shape, but endopodal lobe reaching proximal 1/4 of exopod, with 2 spiniform apical setae; exopod with 2 densely plumose outer setae, 1 pinnate apical spiniform element (proximally plumose) and 1 pinnate spiniform inner seta.

P6 (Fig. 9 C) asymmetrical, represented by membranous flaps covering genital aperture; each lobe with 1 row of fine setules ventrolaterally.

Variability: Both sexes exhibited some variability in the L/W ratio of the caudal ramus (12-14.6 in females; 13.6-17.3 in males) and the L/W ratio of the exopod of P5 (7.1-10.0 in females; 5.3-7.2 in males).

Etymology: The specific name is derived from the Latin adjective Stylicletodes trifidus , meaning "cleft into three" and refers to the characteristic shape of the rostrum with trifurcated processes at the tip. It is in the nominative singular, gender masculine.

Figures

Figure 2. Stylicletodes trifidus sp. nov. Female A habitus, dorsal view; B habitus, lateral view; C rostrum. Male D habitus, dorsal view.

Figure 3. Stylicletodes trifidus sp. nov. Female A urosome, dorsal view, with setae on caudal rami numbered using Roman numerals; B urosome, lateral view; C urosome, ventral view.

Figure 4. Stylicletodes trifidus sp. nov. Female A antennule; B antenna; C mandible; D maxillule; E maxilla.

Figure 5. Stylicletodes trifidus sp. nov. Female A a photograph of cephalothorax by DIC microscope, ventral view; B a line drawing of cephalothorax, ventral view. Asterisk (*) represents the assumed position of the maxilliped and Mx indicates the position of the maxilla.

Figure 6. Stylicletodes trifidus sp. nov. Female A P 1, anterior; B P 2, anterior.

Figure 7. Stylicletodes trifidus sp. nov. Female A P 3, anterior; B P 4, posterior.

Figure 8. Stylicletodes trifidus sp. nov. Female A P 5, anterior, arrowheads indicating tube pores; B P 6.

Figure 9. Stylicletodes trifidus sp. nov. Male A antennule, armature omitted; B antennule; C urosome, ventral view; D caudal ramus, lateral view, setae III-VI omitted. Asterisk (*) indicates the small fourth segment of the antennule.

Figure 10. Stylicletodes trifidus sp. nov. Male A P 3, anterior, arrowhead indicates the apophysis; B P 5, anterior.