Mothocya parvostis Bruce, 1986

Pittella, Renan S., Bassa, Pedro G., Zefa, Edison & Bianchi, Filipe M., 2023, Figs. 18 - 21 in Using the Integrative Approach to Update a Gap of One Century: Redescription and New Distribution Records of the South American Tarantulas (Araneae: Mygalomorphae: Theraphosidae)., Zoological Studies 62 (21), pp. 1-22 : 5-16

Mothocya parvostis Bruce, 1986 ( Figs. 2 , 3 , 9–16 )

Material examined: Juvenile (TL 7.19 mm), from the coast of Nomijima Island, Hiroshima Bay, Seto Inland Sea, Japan, 34°13'49.6"N 132°23'18.4"E, in a opercular cavity of juvenile of Hypoatherina tsurugae (SL: 50.84 mm), 14 October 2021, coll. H. Fujita. Juvenile (TL 6.89 mm), from the coast of Nomijima Island, Hiroshima Bay, Seto Inland Sea, Japan, 34°11'43.3"N 132°26'33.4"E, collected in a opercular cavity of juvenile of Acanthopagrus schelgelii (SL: 23.27 mm), 8 January 2022, coll. H. Fujita. Manca (TL 3.12 mm), from the coast of Nomijima Island, Hiroshima Bay, Seto Inland Sea, Japan, 34°13'49.6"N 132°23'18.4"E, collected in a opercular cavity of juvenile of Hypoatherina tsurugae (SL: 14.5 mm), 6 July 2021, coll. H. Fujita. Manca (TL 2.96 mm), from the coast of Nomijima Island, Hiroshima Bay, Seto Inland Sea, Japan, 34°11'43.3"N 132°26'33.4"E, collected in a opercular cavity of juvenile of Acanthopagrus schelgelii (SL: 12.22 mm), 27 October 2021, coll. H. Fujita.

Description of juvenile infesting H. tsurugae ( Figs. 9 , 10 ): Body elliptical, 2.9–3.0 times as long as greatest width, dorsal surfaces convex, widest at pereonite 5, most narrow at pleonite 1. Cephalon 1.4 times wider than long, semi triangle, slightly immersed in pereonite 1. Anterior margin produced moderately rostrum. Eyes oval with distinct margins, one eye 0.3–0.4 times width of cephalon; 0.3–0.8 times length of cephalon. Pereonite 1 anterior border medially straight, slightly curved laterally. Coxae 2–7 slightly visible or invisible in dorsal view; coxae strongly narrow. Pereonites 5 longest, pereonite 7 shortest; posterior margins smooth, slightly curved laterally; pereonites 7 with slightly recessed posterior margin. Pleon 0.2 times as total length, pleonites all visible in dorsal view, pleon 0.7–0.8 times as wide as greatest body width. Pleotelson 0.8–0.9 times length as wide, 1.6–1.7 times as long as pleon, posterior margin with short marginal setae.

Antennula with 8 articles, reaching posterior margin of cephalon.

Antenna with 8 articles, beyond anterior margin of pereonite 1.

Pereopod 1, basis 1.5 times as long as greatest width; ischium 0.6 times as long as basis; merus 0.6

Sampling days times as long as ischium; carpus 0.4 times as long as merus; propodus 5 times as long as carpus; dactylus 1.1 times as long as propodus. Pereopod 2 similar to pereopod 1. Pereopod 3, basis 1.7 times as long as greatest width; ischium 0.5 times as long as basis; merus 0.6 times as long as ischium; carpus 0.6 times as long as merus; propodus 3.3 times as long as carpus; dactylus 1.25 times as long as propodus. Pereopod 4, basis 1.8 times as long as greatest width; ischium 0.8 times as long as basis; merus 0.4 times as long as

0.020 0.020

ischium; carpus 1.0 times as long as merus; propodus 2.5 times as long as carpus; dactylus 1.1 times as long as propodus. Pereopods 5 and 6 similar to pereopod 4. No robust setae on pereopods 1–6. Pereopod 7, basis 2.3 times as long as greatest width; ischium 0.7 times as long as basis, 1 robust seta on inferior margin; merus 0.6 times as long as ischium; carpus 1.0 times as long as merus, 2 robust setae on inferior margin; propodus 1.7 times as long as carpus, 4 robust setae on inferior margin; dactylus 1.0 times as long as propodus.

Pleopods all lamellar, surface smooth. Pleopod 1 peduncle 1.7 times as wide as length, medial margin with 4 coupling hooks; endopod rectangular, 1.9 times as long as width; exopod trapezoidal, lateral margin almost straight, 1.9 times as long as width, 1.1 times as long as endopod, medial margin with short marginal setae. Pleopod 2 similar to pleopod 1; peduncle medial margin with 4 plumose setae; endopod with appendix masculina, slightly shorter than endopod.

Uropod rami beyond posterior margin of pleotelson; uropod, peduncle triangular, 0.7 times as long as exopod, 1.7 times as long as wide. Endopod oval, 2.3 times as long as greatest width, 0.8 times as long as exopod, lateral and medial margins with short marginal setae. Exopod semitriangular, 3.2 times as long as greatest width, medial margin with short marginal setae.

Description of juvenile infesting A. latus ( Figs. 11 , 12 ): Similar to juvenile infesting H. tsurugae . Body widest at pereonite 1–3, most narrow at pereonite 7. Pereonites 3 longest, pereonite 7 shortest. Each of pereopod 2 and 3 merus superior distal angle with 1 robust seta. Pereopod 6 propodus inferior margin with 1 robust seta. Pereopod 7 carpus and propodus with no robust seta. Pleopod 1 peduncle medial margin with 3 plumose setae.

Description of juvenile infesting H. sajori : Similar to juvenile infesting H. tsurugae and A. latus . Absence of marginal setae of pleotelson, pleopods and uropods.

Description of manca infesting H. tsurugae ( Figs. 13 , 14 ): Body elliptical, 3.4–4.1 times as long as greatest width, widest at pereonite 3, most narrow at pleonite 1. Pereonites 1 longest, pereonite 7 shortest; posterior margins straight. Pleon 0.3 times as total length, pleonites all visible in dorsal view, pleon 0.7–0.8 times as wide as greatest body width. Pleotelson 0.9–1.0 times as wide as length 0.7 times as long as pleon, posterior margin with marginal setae.

Comparison level No. species Intraspecific Interspecific Min. (%) Max. (%) Mean (%) Min. (%) Max. (%) Mean (%) Genus Anilocra 2 0.000 0.349 0.202 10.959 11.187 11.028 Ceratothoa 4 0.169 2.593 1.221 18.398 31.589 29.224 Nerocila 2 0.000 1.280 0.444 27.307 28.836 27.721 Mothocya 4 0.000 1.020 0.261 3.126 13.902 11.752 Mothocya # 4 0.000 1.020 0.310 3.126 14.122 11.781

parvostis collected in the present study. obtained using the Kimura two-parameter model for the 16S rRNA gene sequences of

Antennula with 8 articles, reaching beyond midpoint of cephalon.

Antenna with 8 articles, reaching posterior margin of cephalon.

Pereopod 1, basis 2.2 times as long as greatest width; ischium 0.5 times as long as basis; merus 0.6 times as long as ischium; carpus 0.4 times as long as merus; propodus 4.8 times as long as carpus, 3 robust setae on inferior margin; dactylus 1.2 times as long as propodus, teeth on inferior margin. Pereopod 2 similar to pereopod 1, carpus, 1 robust seta on superior distal angle. Pereopod 3 similar to pereopod 1. Pereopod 4, basis 1.8 times as long as greatest width; ischium 0.8 times as long as basis; merus 0.3 times as long as ischium; carpus 1.3 times as long as merus; propodus 2.2 times as long as carpus, 1 robust seta on inferior margin; dactylus 1.1 times as long as propodus, without teeth. Pereopod 5 similar to 4, absence of robust seta. Pereopod 6 similar to pereopod 4, carpus, 1 robust seta on inferior margin; propodus, 3 robust setae on inferior margin. No pereopod 7.

Pleopods all lamellar, surface smooth. Pleopod 1 peduncle 1.7 times as wide as length, medial margin with 4 coupling hooks; endopod trapezoidal, 1.6 times as long as width; exopod trapezoidal, lateral margin almost straight, 1.8 times as long as width, subequal length of endopod, posterior margin with long marginal setae. Pleopod 2 similar to pleopod 1; endopod without appendix masculina; exopod, 1.1 times as long as endopod.

Uropod rami beyond posterior margin of pleotelson; uropod, peduncle triangular, 0.7 times as long as exopod, 1.7 times as long as wide. Endopod oval,1.6 times as long as greatest width, 0.6 times as long as exopod, lateral and medial margins with long marginal setae. Exopod semitriangular, 3.2 times as long as greatest width, medial margin with long marginal setae.

Description of manca infesting A. latus ( Figs. 15 , 16 ): Similar to manca infesting H. tsurugae .

Pereopod 1, merus, 1 robust seta on inferior margin, 1 robust seta on superior distal angle; propodus, 2 robust setae on inferior margin; dactylus without teeth. Pereopod 2, merus, 1 robust seta on superior distal angle; carpus without robust seta; propodus, 1 robust seta on inferior margin. Pereopod 3, merus, 1 robust sera on superior distal angle; propodus, 3 robust setae on inferior margin. Pereopod 4 without robust seta and teeth. Pereopod 5, dactylus, teeth on inferior margin. Pereopod 6, carpus with 1 robust seta on inferior margin; propodus with 2 robust setae on inferior margin.

Pleopod 1 peduncle, medial margin with 3 plumose setae. Pleopod 2 peduncle, medial margin with 4 plumose setae.

Manca in blood pouch of ovigerous females infesting H. sajori : Similar to manca infesting H. tsurugae and A. latus .

Remarks: Morphological differences between mancae and juveniles of M. parvostis infesting H. tsurugae and those infesting A. latus were mainly found in the setations on the pereopods. The morphology of robust setae may be a key to morphological species identification for cymothoid mancae and juveniles (Saito and Fujita 2022). Morphological differences of Cymothoidae among species, growth stages, and individuals should be comprehensively examined.

Cymothoid juveniles infesting juveniles of A. latus and H. tsurugae have marginal setae on the posterior margin of the pleotelson, endopod of pleopods, and uropods, but absence of those of Juveniles infesting H. sajori . These marginal setae, also known as swimming setae, enhance the swimming ability of cymothoids ( Tsai and Dai 1999). This indicates that juveniles infesting A. latus and H. tsurugae have better swimming ability than those infesting H. sajori .

Figures

Fig. 2. Juveniles of cobaltcap silverside Hypoatherina tsurugae and yellowfin seabream Acanthopagrus latus infested with Mothocya parvostis. Arrows indicate M. parvostis. Scale bars = 5 mm.

Fig. 3. Dorsal and ventral views of Mothocya parvostis infesting juveniles of cobaltcap silverside Hypoatherina tsurugae (A and B) and yellowfin seabream Acanthopagrus latus (C and D). A and C: mancae, B and D: M. parvostis juveniles. Scale bars = 1 mm.

Fig. 9. Mothocya parvostis juvenile (7.19 mm) infesting a cobaltcap silverside Hypoatherina tsurugae juvenile (50.84 mm). (A) Body, dorsal view. (B) Cephalon, ventral view. (C) Pleotelson. (D, E) Pereopods 1, 2, respectively. Scale bars: A–C = 1 mm; D, E = 0.2 mm.

Fig. 10. Mothocya parvostis juvenile (7.19 mm) infesting a cobaltcap silverside Hypoatherina tsurugae juvenile (50.84 mm). (A–E) Pereopods 3–7, respectively. (F, G) Pleopods 1, 2, respectively. Scale bars = 0.2 mm.

Fig. 11. Mothocya parvostis juvenile (6.89 mm) infesting a yellowfin seabream Acanthopagrus latus juvenile (23.27 mm). (A) Body, dorsal view. (B) Cephalon, ventral view. (C) Pleotelson. (D, E) Pereopods 1, 2, respectively. Scale bars: A–C = 1 mm; D, E = 0.2 mm.

Fig. 12. Mothocya parvostis juvenile (6.89 mm) infesting a yellowfin seabream Acanthopagrus latus juvenile (23.27 mm). (A–E) Pereopods 3–7, respectively. (F, G) Pleopods 1, 2, respectively. Scale bars = 0.2 mm.

Fig. 13. Mothocya parvostis manca (3.12 mm) infesting a cobaltcap silverside Hypoatherina tsurugae juvenile (14.54 mm). (A) Body, dorsal view. (B) Cephalon, ventral view. (C) Pleotelson. (D, E) Pereopods 1, 2, respectively. Scale bars: A = 1 mm; B, C = 0.2 mm; D, E = 0.1 mm.

Fig. 14. Mothocya parvostis manca (3.12 mm) infesting a cobaltcap silverside Hypoatherina tsurugae juvenile (14.54 mm). (A–D) Pereopods 3–6, respectively. (E, F) Pleopods 1, 2, respectively. Scale bars = 0.1 mm.

Fig. 15. Mothocya parvostis manca (2.96 mm) infesting a yellowfin seabream Acanthopagrus latus juvenile (12.22 mm). (A) Body, dorsal view. (B) Cephalon, ventral view. (C) Pleotelson. (D, E) Pereopods 1, 2, respectively. Scale bars: A = 1 mm; B, C = 0.2 mm; D, E = 0.1 mm.

Fig. 16. Mothocya parvostis manca (2.96 mm) infesting a yellowfin seabream Acanthopagrus latus juvenile (12.22 mm). (A–D) Pereopods 3–6, respectively. (E, F) Pleopods 1, 2, respectively. Scale bars = 0.1 mm.