Cymothoa bychowskyi Avdeev, 1979

Aneesh, Panakkool Thamban, Helna, Ameri Kottarathil & Kumar, Appukuttannair Biju, 2022, Redescription and further report of two buccal attaching fish parasitic cymothoids, Ceratothoa carinata (Bianconi, 1869) and Cymothoa bychowskyi Avdeev, 1979 (Crustacea: Isopoda) with a new record from the southern India Ocean, Journal of Natural History 56 (17 - 20), pp. 1063-1089 : 1072-1080

Cymothoa bychowskyi Avdeev, 1979

( Figures 5–11 )

Cymothoa bychowskyi Avdeev, 1979a: 230 , pl. 6, 7; 1985: 217, fig. 1. – Trilles 1994: 138. – Williams et al. 2000: 157. – Kensley 2001: 232. – Bruce et al. 2002: 174. – Paulay et al. 2003: 479. – Trilles and Bariche 2006: 228. – Rameshkumar et al. 2013: 42, fig. 1(C). – Martin et al. 2016: 6. – Ravichandran et al. 2019: 18 , fig. 1J–l.

Material examined

Four females and two males.

Voucher specimens

All from Fistularia petimba Lacepède, 1803 , 1♀ (ovig., 24.5 mm L, 11.5 mm W), ( DABFUK / AR-IS-02); 1♂ (14.5 mm L, 7.0 mm W), (Reg. no. DABFUK/AR-IS-03); 1♀ (ovig., 24.0 mm L, 11.5 mm W))(Reg. no. DABFUK/AR-IS-26); 1♀ (ovig., 25.0 mm L, 12.0 mm W))(Reg. no. DABFUK/AR-IS-27) partially dissected; 1♂ (14.0 mm L, 6.8 mm W), (Reg. no. DABFUK/AR-IS -28) partially dissected, coll . P. T. Aneesh from Tuticorin, Tamil Nadu, south-eastern India, 26 May 2018 .

Description

Ovigerous female ( Figures 5–9 ). Body elongate, 2.1 times as long as greatest width, dorsal surfaces rugose, widest at pereonite 4, narrowest at pereonite 1, lateral margins slightly convex. Cephalon 0.4 times as long as wide, visible in dorsal view, anterior margin rounded, immersed in pereonite 1. Frontal margin rounded to form blunt rostrum and thickened, ventrally folded. Eyes not visible. Pereonite 1 with slight indentations, anterior border slightly indented, anterolateral angle rounded, posterior margins of pereonites smooth, slightly curved laterally. Coxae 2–3 with posteroventral angles acute, posteriorly produced; 4–7 rounded. Pereonites 1–4 increasing in length and width; 5–7 decreasing in width; 5–6 subequal in length; pereonite 7 shortest. Pleon with all pleonites visible; pleonite 1 as wide as pleonite 2; pleonites increasing in width from 3 to 5; pleonites posterior margin smooth; posterolateral angles of pleonite 2 rounded, not posteriorly produced. Pleonite 5 posterior margin indented medially. Pleotelson 0.6 times as long as anterior width, dorsal surface with medial furrow, lateral margins weakly concave, posterior margin sub-truncate, without median point.

Antennule stouter than antenna, comprised of 8 articles; article 1, 0.6 times as long as wide; article 2, as long as article 1; article 3, 1.4 times as long as article 1, 1.2 times as long as wide; articles 4–8 gradually decreasing in width; article 8 with 8–10 short, simple terminal setae. Antenna comprised of 9 articles; article 1, 0.6 times as long as wide; article 2, 0.7 times as long as wide, 1 time as long as article 1; article 3, 0.8 times as wide as article 2; article 4 subequal to 3; articles 5–9 gradually decreasing in width; article 9 with 8–10 short, simple terminal setae. Mandibular process ending in acute incisor, mandible palp article 2 without distolateral setae, article 3 without terminal setae. Maxillule simple, with 4 terminal RS. Maxilla mesial lobe partly fused to lateral lobe; lateral lobe and mesial lobe with 4 recurved RS each. Maxilliped weakly segmented, with lamellar oostegite lobe, palp article 2 without setae, article 3 with 4 recurved RS; oostegites lobes without marginal plumose setae.

Pereopod 1 basis 1.4 times as long as greatest width; ischium 0.7 times as long as basis, 1.7 times as long as greatest width; merus proximal margin without bulbous protrusion; carpus with straight proximal margin; propodus 1.7 times as long as wide; dactylus slender, 1.1 times as long as propodus, 2.2 times as long as basal width. Pereopod 2 basis 1.3 times as long as greatest width; ischium 0.6 times as long as basis; merus 0.7 times as long as wide, 0.4 times as long as ischium; propodus 1.2 times as long as wide; dactylus slender, 1.7 times as long as propodus, 2 times as long as basal width. Pereopod 3 basis 1.3 times as long as greatest width; propodus 1.2 times as long as wide, 0.5 times as long as basis; dactylus slender, 1.7 times as long as propodus, 2.3 times as long as basal width. Pereopod 4 basis as long as greatest width; ischium 0.6 times as long as basis, 1.5 times as long as greatest width; merus 0.5 times as long as ischium; propodus 1.1 times as long as wide; dactylus, 2.1 times as long as propodus, 2.8 times as long as basal width. Pereopod 5 basis 1.1 times as long as greatest width; ischium 0.6 times as long as basis; propodus 1.3 times as long as wide; dactylus slender, 1.9 times as long as propodus, 2.1 times as long as basal width. Pereopod 6 basis as long as greatest width, ischium 0.7 times as long as basis, propodus 1.3 times as long as wide, dactylus 1.7 times as long as propodus. Pereopod 7 basis 1.1 times as long as greatest width; ischium 0.6 times as long as basis; merus as long as wide, 0.5 times as long as ischium; propodus 0.6 times as long as ischium, 1.3 times as long as wide; dactylus, 1.6 times as long as propodus, 2.6 times as long as basal width.

Pleopods peduncle without setae, exopod larger than endopod. Pleopod 1 exopod as long as wide, lateral margin weakly convex; endopod as long as wide, lateral margin weakly concave, distally narrowly rounded, mesial margin straight, peduncle 0.4 times as wide as long, without retinaculae. Pleopod 2 exopod 1.1 times as long as wide, lateral margin weakly convex; endopod 1.3 times as long as wide, lateral margin weakly concave, distally narrowly rounded, mesial margin straight, peduncle 0.3 times as wide as long, without retinaculae. Pleopods 3–5 similar to pleopod 2, mesial margins becoming more strongly produced. Pleopods 3–5 endopods with large fleshy folds; folds well developed in pleopods 4 and 5.

Uropod 0.8 times the length of pleotelson, peduncle 0.7 times longer than exopod, 0.8 times as long as wide, peduncle lateral margin without setae; rami not extending beyond pleotelson, marginal setae absent, apices narrowly rounded. Endopod apically rounded, 4.4 times as long as greatest width, 0.8 times as long as exopod, lateral margin weakly convex, mesial margin weakly convex. Exopod extending to almost end of endopod, 5.4 times as long as greatest width, apically rounded, lateral margin weakly convex, mesial margin weakly convex.

Male ( Figures 10–11 ). Similar to female but smaller, body oval, elongate, 2.1 times as long as wide. Cephalon visible in dorsal view, 0.9 times as long as wide. Pereonite 1 anterolateral margins slightly produced. Pleotelson 2 times as wide as long; posteriorly rounded. Pleopods simple, with fewer folds on endopod. Pleopod 2 with appendix masculina, as long as endopod. Uropod 0.7 times the length of pleotelson, peduncle 0.7 times longer than exopod, 0.7 times as long as wide, peduncle lateral margin without setae; rami not extending beyond pleotelson, marginal setae absent, apices narrowly rounded. Endopod apically rounded, 0.8 times as long as exopod, lateral margin weakly convex, mesial margin weakly convex. Exopod extending to almost end of endopod, apically rounded, lateral margin weakly convex, mesial margin weakly convex.

Hosts

Known only from the family Fistulariidae : Fistularia petimba Lacepède, 1803 (see Avdeev 1979a; Williams et al. 2000; Rameshkumar et al. 2013; present study) and blue spotted cornetfish Fistularia commersonii Rüppell, 1838 ( Williams et al. 2000).

Distribution

North-western and Western Australia ( Avdeev 1979a; Kensley 2001); Guam, Micronesia ( Williams et al. 2000), Okinawa, Japan ( Williams et al. 2000) and Lakshadweep, India ( Rameshkumar et al. 2013); south-west coast India (present study).

Figures

Figure 5. Cymothoa bychowskyi Avdeev, 1979 from Fistularia villosa Klunzinger, ovigerous female (DABFUK/AR-IS-02). A, Dorsal view; B, ventral view.

Figure 6. Cymothoa bychowskyi Avdeev, 1979 from Fistularia villosa Klunzinger, ovigerous female (DABFUK/AR-IS-02). A, Dorsal view; B, ventral view; C, lateral view.

Figure 7. Cymothoa bychowskyi Avdeev, 1979 from Fistularia villosa Klunzinger, ovigerous female (DABFUK/AR-IS-02). A, Cephalon, dorsal view; B, cephalon, ventral view; C, antennula; D, antennula apex; E, antenna; F, antenna apex; G, mandible; H, maxilla; I, maxilliped; J, maxilliped article 3.

Figure 8. Cymothoa bychowskyi Avdeev, 1979 from Fistularia villosa Klunzinger, ovigerous female (DABFUK/AR-IS-02). A–G, Pereopods 1–7, respectively; H, brood pouch.

Figure 9. Cymothoa bychowskyi Avdeev, 1979 from Fistularia villosa Klunzinger, ovigerous female (DABFUK/AR-IS-02). A–E, Pleopods 1–5; F, uropod; G, pleotelson and uropods.

Figure 10. Cymothoa bychowskyi Avdeev, 1979 from Fistularia villosa Klunzinger, male (DABFUK/AR-IS-03). A, Dorsal view; B, ventral view; C, lateral view.

Figure 11. Cymothoa bychowskyi Avdeev, 1979 from Fistularia villosa Klunzinger, male (DABFUK/AR-IS -03). A, Dorsal view; B, cephalone, dorsal view; C, pleotelson and uropods.