Lucicutia gaussae Grice, 1963

Lee, Seok Ju & Soh, Min Ho Seo and Ho Young, 2024, First record of Lucicutia gaussae (Calanoida, Lucicutiidae) from Korean waters, Journal of Species Research 13 (2), pp. 178-184 : 179-182

Lucicutia gaussae Grice, 1963 ( Figs. 2-5 )

Korean name: Šųü형ṻljṉẅƚḍNj (ṳḋ)

Lucicutia ovalis Wolfenden, 1906: p. 28 , pl. 9, figs. 7-10; Wolfenden, 1911: p. 319, fig. 61; Mori, 1937 (1964): p. 72, pl. 36, figs. 6-13; Grice, 1962: p. 222, pl. 24, figs. 5-9; Chen and Zhang, 1965: p. 84, pl. 33, figs. 7-12.

Lucicutia gaussae Hulsemann, 1966: p. 715 , figs. 92, 93, 122; Ali-Khan and Ali-Khan, 1982: p. 267, figs. 14-18; Bradford-Grieve et al., 1999: p. 883, 945, fig. 7.304; Prusova et al., 2012: p. 173, figs. 166-169.

Material examined. 1♀ ( MABIK CR00254251 ) dissect- ed in 12 slides glasses , 1♂ ( MABIK CR00254252 ) dissected in 12 slides glasses , 17♀♀, 25♂♂, South Sea (St. 1), 33°50 ʹ 21.23 ʺ N, 126°46 ʹ 43.78 ʺ E, Oct. 2022 ; 11♀♀, 4♂♂, East China Sea (St. 2), 31°30 ʹ 0 ʺ N, 125°53 ʹ 3 ʺ E, Nov. 2022 ; 3♀♀, 1♂, East China Sea (St. 3), 31°30 ʹ 0 ʺ N, 126°28 ʹ 59.88 ʺ E, Nov. 2022 . 20 individuals were used for length measurement.

Description. Female. Body length 1.35-1.47 mm (n = 10). Body elongated; cephalosome separated from first pedigerous somite; cephalosome rounded, without protrusions; rostrum with a pair of slender filaments; fourth and fifth pedigerous somites fused; posterolateral corners of fourth pedigerous somite symmetrical and rounded( Fig. 2A, B ). Urosome 4-segmented; genital double somite in dorsal view about as wide as long, and in lateral view with ventral protrusion; anal segment slightly long than second and third urosomites; anal segment and caudal rami separated( Fig. 2A, B ). Caudal rami symmetrical, slightly long and wide. Caudal rami with 6 setae, second terminal setae longer than other terminal setae( Fig. 2A, B ).

Antennule symmetrical, longer than body length. 25-segmented ( Fig. 2C ). Fusion pattern and setal formula as follows: I-III-5 + 3ae (aesthetasc), IV-2 + ae, V-2 + ae, VI-2 + ae, VII-2 + ae, VIII-2 + ae, IX-2 + ae, X-2 + ae, XI-2+ ae, XII-2 + ae, XIII-2 + ae, XIV-2 + ae, XV-2 + ae, XVI-2 + ae, XVII-2 + ae, XVIII-2 + ae, XIX-2 + ae, XX-2 + ae, XXI-2 + ae, XXII-1, XXIII-1 + ae, XXIV-1 + 1, XXV-1 + ae, XXVI-1 + 1, XXVII-XXVIII-6 + ae.

Antenna biramous ( Fig. 3A ), exopod slightly larger than endopod; coxa with 1 seta; basis with 1 seta; endopod 2-segmented, first endopodal segment with 2 setae at about middle, row of spinules on distal; second endopodal segment with 7 and 6 setae on proximal and distal lobes, respectively and row of spinules on distal lobe; exopod 8-segmented with setal formula 1, 1, 1, 1, 1, 1, 1, 4.

Mandible with coxal gnathobase and biramous palp; gnathobase with 9 sharp teeth; basis of mandibular palp with 4 setae; endopod 2-segmented, setal formula 4, 10; exopod 5- segmented, setal formula 1, 1, 1, 1, 2( Fig. 3B ).

Maxillule praecoxal arthrite with 13 stout setae; coxal endite with 3 setae and epipodite with 5 setae; basis proximal and distal endite with each 3 setae; endopod 1-segmented, with 4 + 5 setae; exopod 1-segmented, with 11 setae ( Fig. 3C ).

Maxilla 7-segmented; praecoxa with 2 endites, proximal with 4 setae, distal 3 setae; coxa with 2 endites, with each 3 setae; basis with 3 setae; endopod indistinctly 4-segmented, setal formula 2, 1, 2, 3 ( Fig. 3D ).

Maxilliped 7-segmented; coxa fringed with row of small teeth distally, endite setal formula 0, 1, 2, 2; basis fringed with row of small teeth, small setula distally and with 3 setae; first endopodal segment almost fully incor- porated into basis with 2 setae; endopod 5-segmented, segmental setal formula 2, 2, 2, 2, 3 + 1 ( Fig. 3F ).

Legs 1 to 4 biramous: leg 1 with 2-segmented endopod and 3-segmented exopod, leg 2 to 4 with 3-segmented endopod and 3-segmented exopod ( Fig. 4A- D ). Coxa of leg 1 without seta; basis with cylindrical process, with slender inner basal seta ( Fig. 4A ). Coxa of leg 2 to 4 with inner marginal seta ( Fig. 4B- D ). Setae and spine formula of leg 1 to 4 as follows (spines, Roman numerals; setae, Arabic numerals):

Exopodal Endopodal

Coxa Basis

segment segment Leg 1 0-0 0-1 I-1; I-1; II,I,4 0-1; 1,2,3 Leg 2 0-1 0-0 I-1; I-1; III,I,5 0-1; 0-2; 1,2,3 Leg 3 0-1 0-0 I-1; I-1; III,I,5 0-1; 0-2; 1,2,3 Leg 4 0-1 0-0 I-1; I-1; III,I,5 0-1; 0-2; 1,2,3

Fifth leg symmetrical: coxa without seta, and basis with outer seta; endopod and exopod with each 3-segmented; endopod not reach 1/2 of the second exopodal segment; inner marginal spine of second exopodal segment than about 1/2 length of third exopodal segment; terminal seta of third exopodal segment short, less than about 1/3 length of segment( Fig. 2D ).

Male: Body length 1.25-1.41 mm (n = 10). Similar in habitus to female except urosome. Urosome 5-segmented; anal segment almost same length as previous urosomite; anal segment and caudal rami separated( Fig. 5A, B ). Leg 1 to 4 similar to female.

Left antennule geniculate, reaching of anal segment. 21-segmented ( Fig. 5C, D ). Fusion pattern and setal formula as follows: I-III-6 + 3ae (aesthetasc), IV-2 + ae, V-2 + ae, VI-2 + ae, VII-2 + ae, VIII-2 + ae, IX-2 + ae, X-2 + ae, XI-2 + ae, XII-2 + ae, XIII-2 + ae, XIV-2 + ae, XV-2 + ae, XVI-2 + ae, XVII-2 + ae, XVIII-1 + ae, XIX-XX-1 + ae, XXI-XXIII-2 + ae, XXIV-XXV-3 + ae, XXVI-1 + 1, XXVII-XXVIII-6 + ae. Segments XVIII and XIX-XX each with 1 process; segments XXI-XXIII with 3 processes.

Fifth leg asymmetrical: coxa without seta ( Fig. 5E ). Right leg biramous and basis with outer seta; basis smooth with no protrusion; endopod and exopod 2-segmented; second endopodal segment broadly oval-shaped; second exopodal segment curved, setal bundles in medial side; distal margin of segment with spine ( Fig. 5E, G ). Left leg biramous and basis with outer seta; mediodistal margin of basis with large protrusion, adorned small spine processes; endopod and exopod 3-segmented; first and second exopodal segment with outer marginal spine; third exopodal segment with outer marginal spine and terminal spine ( Fig. 5E, F ).

Distribution. Lucicutia gaussae was recorded in the Atlantic Ocean ( Wolfenden, 1906; 1911), East China Sea ( Mori, 1937 (1964)), Pacific Ocean ( Grice, 1962), North Atlantic Ocean ( Grice, 1963), and Arabian Sea ( Ali-Khan and Ali-Khan, 1982; Prusova et al., 2012).

Remarks. The morphological description of Lucicutia gaussae was not detailed in previous records. The male antennule of Lucicutiidae family has 1 process on segments XIX and XX, 2 processes on segment XXI, and has morphological characteristics with or without process on segments XXII-XXIII (Boxshall and Hasley, 2004). The male antennule of the Korean specimen has 1 process on segments XIX-XX and 3 processes on segments XXI-XXIII, similar to the morphological characteristics of males of the Lucicutiidae family, but additionally has 1 process on segment XVIII. The right leg basis of male leg 5 is smooth form and is not similar to other Lucicutia species. The basis of the left leg 5 of the male in the Korean specimen has small spine processes on the protrusion, but in previous records ( Hulsemann, 1966; Ali-Khan and Ali-Khan, 1982; Bradford-Grieve et al., 1999; Prusova et al., 2012) the protrusion has a pointed shape in the distal direction. In the third exopodal segment of the left leg, an inner marginal spine was present in previous records ( Hulsemann, 1966; Ali-Khan and Ali-Khan, 1982; Prusova et al., 2012), but it was not present in the Korean specimen. In female, an individual that appears to have morphological variation was collected from the Korean specimen. The female’s right caudal ramus partially adorned with small spines at part adjacent to anal segment. In leg 5, the endopod extends beyond the first exopodal segment, consistent with previous records, but in the record by Ali-Khan and Ali-Khan (1982), the endopod reaches halfway to the second exopodal segment.

Figures

Fig. 2. Lucicutia gaussae Grice, 1963, female.A, Habitus, dorsal; B, Habitus, right lateral; C, Antennule; D, Leg 5. Scale bars in μm.

Fig. 3. Lucicutia gaussae Grice, 1963, female.A, Antenna; B, Mandible; C, Maxillule; D, Maxilla; E, Maxilliped. Scale bars in μm.

Fig. 4. Lucicutia gaussae Grice, 1963, female.A, Leg 1; B, Leg 2; C, Leg 3; D, Leg 4. Scale bars in μm.

Fig. 5. Lucicutia gaussae Grice, 1963, male. A, Habitus, dorsal; B, Habitus, right lateral; C, Left antennule; D, Left antennule XVIII-XXIII segment; E, Leg 5; F, Left leg 5; G, Right leg 5. Scale bars in μm.