Entoniscus creplinii Giard and Bonnier, 1887

McDermott, John J., Williams, Jason D. & Boyko, Christopher B., 2022, Rediscovery and redescription of Entoniscus creplinii Giard and Bonnier, 1887 (Isopoda: Bopyroidea: Entoniscidae) parasitizing Polyonyx gibbesi Haig, 1956 (Decapoda: Anomura: Porcellanidae), a symbiotic crab from the tubes of Chaetopterus cf. variopedatus (Annelida), from North Carolina and Florida, U. S. A., Nauplius (e 2022010) 30, pp. 1-10 : 3-5

Entoniscus creplinii Giard and Bonnier, 1887

( Figs. 1–2 )

Entoniscus 3 Müller, 1871: 54 (brief description; see below).

“ Entoniscus …im Porcellana Creplinii ” Fraisse, 1878: 25, 387 (mention).

“L’ Entoniscus de Porcellana Creplinii ” Giard, 1878: 683 (mention).— Giard and Bonnier, 1887: 89 (mention).

Entoniscus Creplinii Giard and Bonnier, 1887: 231 (table), 236 (after Müller, 1871).— Stebbing, 1893: 406 (mention).— Bonnier, 1900: 227, 380 (lists).

“ Entoniscus … creplinii ” Lucas, 1905: 1048 (list).

Entoniscus creplinii — Shiino, 1942: 51 (mention).— Adkison, 1990: 23, 51, 54 (mention; list).— Brasil Lima,1998:640 (list).— Boos et al. 2012:1036 (list).

Material examined herein (subset of specimens originally examined by JJM). North Carolina: 3 immature females, all parasitizing a single female Polyonyx gibbesi (13.3 mm CW) associated with Chaetopterus cf. variopedatus, Beaufort , coll. J.J. McDermott, 21 June 1966 (specimens fixed 3 July 1966) ( USNM 1660598; specimens in pieces and combined in one lot). Florida: 2 mature females, 1 each parasitizing separate male specimens (7.8 and 8.5 mm CW) of P. gibbesi and 1 immature female parasitizing an ovigerous female (10.1 mm CW) P. gibbesi associated with C. cf. variopedatus, Miami , coll. J. J. McDermott, 9 November 1966 ( USNM 1660599; specimens in pieces and combined in one lot).

Type locality. Desterro (= Florianópolis, state of Santa Catarina), Brazil.

Type host. Porcellana (Polyonyx) creplinii Müller, 1871 (nomen nudum) (= Polyonyx gibbesi Haig,1956 ).

Description of female ( Figs. 1 , 2 ). Mature specimens occupying most of host hemocoel, laying under host stomach, pleon extending dorsally through digestive gland of host to an opening on pereopods 2–4, such as the merus-carpus articulation of right fourth pereopod ( Fig. 1D ), or unidentified positions in the antero-lateral dorsal quarter of the crab; brood chambers of ovigerous specimens extending into spaces of host pleon. Sheath formed by host surrounds entire parasite. Body of mature parasites orange color due to gonad extending as 2 bands along length of body.

Pereon approximately straight from cephalon to posterior end ( Figs. 1A–C , 2A ). Cephalon rounded, dorsally divided into 2 bulbous lobes ( Figs. 1A–C , 2A, D–G ), ventrally undivided, bearing 2(?) pairs of fused flattened antennae ( Fig. 2D–G ), maxillipeds not observed. Pereon lacking ovarian processes, pereopods apparently absent. Five pairs of subequal oostegites, margins highly crenulate ( Figs. 1A–C , 2A ). Oostegite 1 not subdivided in lobes. Oostegites 2–5 not fused, not covering oostegite 1 ( Figs. 1A–C , 2A ).

Pleon elongate (nearly as long or even longer than rest of body in mature specimens), S-shaped, composed of 5 pleomeres, 1 and 2 indistinctly delineated, 3–5 distinct, pleomere 1 as long as remaining pleomeres combined ( Figs. 1A–C , 2A, H ), pleomeres 3–5 with scales ( Fig. 2B ). One pair of crenulate pleural lamellae on pleomere 1, similar in size and shape to oostegites, positioned immediately posterior to oostegite 5 ( Figs. 1B, C , 2A ). Triangular extension on pleomere 1 between pleural lamella and bulbous heart ( Figs. 1A, B , 2A, H ). Pleomeres 1–5 each with pair of uniramous filamentous pleopods, pleopods 1 and 2 widely separated, 3–5 overlapping ( Figs. 1A–C , 2A, H ), pleopods 1 and 2 laying within ventral channel on pleomeres 1 and 2. Terminal pleomere with shallow ventral notch, terminally fringed with minute setae ( Fig. 2C ).

Remarks. Müller’s (1871) description of this species, which he did not name, was very short and the only characters noted were that the ovaries of the female parasites were yellow and not purple as in Entoniscus porcellanae Müller, 1862 and that the oostegites were less divided with smoother margins than those of the latter species. Giard and Bonnier (1887) saw no specimens but named the species based on Müller’s (1871) account. Brief as Müller’s (1871) description was, it was sufficient to make the name available from Giard and Bonnier’s (1887) translation of Müller’s (1871) text into French. Müller (1871) noted that the parasitized hosts were each found alone in the “ Chätopterus” burrows, not in a pair as is typical; he speculated that the parasitized nature of the crabs made them poor choices for mates. The present material also had orange gonads and the oostegites are more compact and less divided than those of E. porcellanae , and so match both the characters described by Müller (1871) for E. creplinii .

Figures

Figure 1.Entoniscus creplinii Giard and Bonnier, 1887 (USNM 1660598). A) Mature female, dorsal view. B) Mature female, dorsal view. C) Mature female, lateral view. D) Pleon of female extending to opening at the merus-carpus articulation of the third right walking leg of host Polyonyx gibbesi Haig, 1956. Abbreviations: ce = cephalon; he = heart; 1o–5o = oostegites 1 to 5; 1p–5p = pleomeres 1 to 5; pl = pleural lamellae. Scales = 0.5 mm (A); 1 mm (B–D).

Figure 2. Entoniscus creplinii Giard and Bonnier, 1887 (USNM 1660598). A) Mature female, lateral view. B) Close-up of side of pleomere 3 showing scales. C) Terminal segment of pleon. D) Female cephalon with host sheath surrounding, en face view. E) Female cephalon with host sheath surrounding, lateralview.F) Female cephalon with host sheath removed, en face view.G) Female cephalon with host sheath removed, lateral view. H) Pleon of female with host sheath partially removed, asterisk showing position of first pleopods still covered by host sheath; stippled region shows channel within which second pleopods lay. Abbreviations: ce = cephalon; he = heart; 2–4 = pleopods 2 to 4. Scales = 0.5 mm (A, D–H); 10 µm (B, C).