Mothocya plagulophora
Creators: name: Ravichandran, S.
name: Vigneshwaran, P.
name: Rameshkumar, G.
Publisher: name: Zenodo
Year: 2019
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Isopoda
Cymothoidae
Mothocya
Mothocya plagulophora

description: Mothocya plagulophora (Haller, 1880)
(Figs 3 g–i, 4, 5)
Livoneca plagulophora Haller, 1880: 380, pl. 18 (figs 8–9).— Nierstrasz, 1931: 144.
Irona vatia Schiöedte & Meinert, 1884: 386–388, pl. XVII (Cym. XXXV), figs 1, 2.— Nierstrasz, 1915: 104–105; 931: 145.— Monod, 1971: 169–176, figs 18 –42; 1976: 863, fig. 33.— Trilles, 1976: 784–785, pl. 1 (fig. 9); 1994: 171.
Irona vatica [lapsus].— Pfeffer, 1889: 36.
Irona melanosticta.— Nierstrasz, 1915: 103–104 [non Mothocya melanosticta (Schiöedte & Meinert, 1884)].
Irona far Nair, 1950: 70–74, pl. 2 (figs 13–23); 1956: 2–33.— Pillai, 1954: 17.— Abraham, 1966: 23–51, figs 1–27.— Monod, 1971: 173.— Thampy & John, 1974: 574–583, figs 1–18.— Radhakrishnan & Nair, 1983: 93–115, fig. 10c.
Mothocya plagulophora.— Bruce, 1986: 1134–1139, figs 25–27, 54.— Trilles, 2008: 26.— Gopalakrishnan, Rajkumar, Jun & Trilles, 2010: 832–835.— Ravichandran, Rameshkumar & Trilles, 2011: 232–234.— Trilles, Ravichandran & Rameshkumar, 2011: 451.—Sethi, Jithendran & Kannappan, 2013: 357–360.— Rameshkumar, Ramesh, Ravichandran, Trilles & Subbiah, 2014b: 1–4.— Vijayakumar, Raja, Velvizhi, Sinduja & Gopalakrishnan, 2014: 331–333.— Hadfield, Bruce & Smit, 2015: 148–150, figs 1, 2, 9 (a).—Ravichandran, Sivasubramanian, Parasuraman, Karthick Rajan & Rameshkumar, 2016a: 1–5, fig. 4.
Type and type locality. The three female syntypes are held at the Museum d’Histoire Naturelle, Geneva, Switzerland (uncatalogued). Haller’s specimens are all one species and a lectotype is not designated. Haller (1880) states Mauritius as the locality from which his specimens originated.
Material examined. 5 ovig. females, (25–29 mm), 3 non ovig. females (21–27 mm), 1 male (13 mm), Parangipettai, 4 January 2015, from Hemiramphus far (Forsskål, 1775), coll. P. Vigneshwaran (CAS / MBRM C- 167– C-175), 1 ovig. female (28 mm) Nagapattinam, 28 December 2016, from Hemiramphus far, coll. S. Ravichandran (ZSI / MBRC D1-539), all from the southeastern coast of India.
Description female. Body weakly twisted, 1.7 times as long as greatest width, dorsal surfaces smooth, widest at pereonites 4 and 5, most narrow at pereonite 1, lateral margins slightly convex. Cephalon 0.6 times longer than wide, visible from dorsal view, ovate. Eyes oval with distinct margins; eye 0.4 times width of cephalon, 0.3 times length of cephalon. Pereonite 1 smooth, anterior border indented, anterolateral angle narrowly rounded, posterior margins of pereonites smooth and straight. Coxae 2 and 3 narrow; 4–7 produced and with rounded point, not extending past pereonite margin. Pereonite 1 longest, pereonites increase in width from 1–3; pereonites 4–7 decreasing in width progressively, pereonite 7 widely recessed. Pleon with pleonite 1 largely concealed by pereonite 7, slightly visible in dorsal view; pleonites posterior margin smooth, mostly concave; pleonite 2 partially overlapped by pereonite 7; pleonite 5 widest, with posterolateral angles narrowly rounded, posterior margin straight. Pleotelson 0.7 times as long as anterior width, dorsal surface smooth, lateral margins weakly convex, posterior margin evenly rounded.
Antennula stouter than antenna, composed of 8 articles; article 3 longest; articles 1–3 slightly wider than others; apex of article 8 curved with many terminal aesthetascs. Antenna with 9 articles, decreasing gradually in width, articles 5–8 with few terminal aesthetascs. Molar process present, mandible palp 3 segmented, without setae. Maxillula with 4 terminal recurved apical spines. Maxilla lateral lobe with 2 recurved robust spines; mesial lobe with 2 large recurved robust spines. Maxilliped article 3 with 3 large terminal recurved spines and small spine on proximomedial surface.
Pereopods 1–7 without spines. Pereopod 1 short, robust; pereopods 2–6 subequal; pereopod 7 longer than others. Exopodite of pleopods 1–5 without seta. Pleopod 2 without appendix masculina. Pleopod 1 with narrow peduncle and undeveloped lateral lobes; pleopods 2–5, peduncles with well-developed lateral lobe; endopods of pleopods 3 and 4 with the well-developed proximomedial lobe. Endopod of pleopod 5 with large proximomedial lobe. Uropod half-length of pleotelson, rami long; rami not extending beyond pleotelson; rami taper gradually. Exopod about 1.5 longer than endopod, apically rounded, lateral margin weakly convex, mesial margin straight, terminating without setae.
Male. Body was not twisted 2.65–2.77 times as long as wide. Rostrum folded back; eye small, distinct width 0.35–0.45 width of the cephalon. Pereonites 4–7 decreasing gradually in width; pereonite 1 longer than others; pereonites 2–6 subequal, pereonite 7 shortest. Pleonites subequal in width, pleotelson shield-shaped, anterolateral margin slightly indented. Antennula, antenna, mouthparts and pereopods essentially similar to those of female. Pleon slightly wider than pereonite 7. Pleopods differ from female in having longer peduncles on pleopods 1 and 2, and endopods of pleopods 3–5 with proximomedial lobe but not folded. Pleotelson as long as wide, uropods longer than female, exopod proportionally longer, about 1–1.5 times length of endopod; both rami with bluntly rounded apices.
Colour. Mothocya plagulophora is the only species of the genus showing a colour pattern of dark bands along the posterior margins of the pleonites and posterior pereonites.
Size. Ovig. females 25–29 mm; non ovig. females 22–27 mm.
Remarks. Mothocya plagulophora can be distinguished from other Mothocya species by the characteristically large and extremely wide pleon and pleotelson. Besides, the unique colour pattern showing dark bands along the pereonite and pleonite posterior margins. Bruce (1986) examined specimens from East Africa lack have these bands and are uniform in colour and also has short uropods, pleonite 5 wider than the other pleonites.
Mothocya plagulophora has been described as Irona far by Nair 1950 and Abraham (1966), but Bruce (1986) observed the colour pattern and pleonal morphology identify their material as M. plagulophora. This is further supported by M. plagulophora occurring only in association with Hemiramphus far, the host species from which Irona far was taken. Irona vatia, by which name this species was better known, is easily recognized from Schiöedte & Meinert’s (1884) figures, Bruce (1986) stated the characteristic pleonal and pteotelson morphology clearly identifies their material as Mothocya plagulophora.
This species previously briefly described by Bruce (1986), Mothocya plagulophora was most recently carefully treated and redescribed the type specimen by Hadfield et al. (2015). Comparison of numerous drawings of the Indian specimen in this study with the drawings and description by Bruce (1986) reveal only minor variations that can be considered as within the range of intraspecific variation shown by species of Mothocya. These isopods are known to be highly variable, as can be seen in the study by Hadfield et al. (2014a) where one species, Ceratothoa retusa (Schiöedte & Meinert, 1883), showed many morphological differences depending on its geographical locality. The two most noticeable variations include the number of maxillipeds recurved robust setae and the size of females. Bruce (1986) reported four recurved robust setae on article 3 of the maxilliped and females ranging from 17–26 mm in length, whereas six recurved robust setae and females measuring 29–30.5 mm are reported by Hadfield et al. (2015).
Distribution. Indian Ocean: Mauritius (Haller 1880; Bruce 1986), Zanzibar (Pfeffer 1889; Bruce 1986), Indonesia (Nierstrasz 1915; Bruce 1986), India (Nair 1950; Pillai 1954; Gopalakrishnan et al. 2010; Ravichandran et al. 2011; Trilles et al. 2011; Sethi et al. 2013; Rameshkumar et al. 2014; Vijayakumar et al. 2014), Madagascar (Monod 1971; Djibouti (Trilles 1976), Comoro Islands, Kenya, Somalia, Sri Lanka, Australia (Bruce 1986) and Mozambique (Hadfield et al. 2015). Schiöedte & Meinert 1884) mentioned a possible occurrence in the Philippines (Mariveles, Luzon Island) but the identity was not confirmed.
Hosts. Known only from the family Hemiramphidae: black-barred halfbeak, Hemiramphus far (Forsskål, 1775) (Bruce 1986; Gopalakrishnan et al. 2010; Ravichandran et al. 2011; Trilles et al. 2011; Rameshkumar et al. 2014b; Vijayakumar et al. 2014), with one record from the yellowtip halfbeak, Hemiramphus marginatus (Forsskål, 1775) (Sethi et al. 2013). There are also unconfirmed records from a Sardinella species (Bruce 1986) and from a belonid host (Monod 1971).
description: Published as part of Ravichandran, S., Vigneshwaran, P. & Rameshkumar, G., 2019, A taxonomic review of the fish parasitic isopod family Cymothoidae Leach, 1818 (Crustacea: Isopoda: Cymothooidea) of India, pp. 1-99 in Zootaxa 4622 (1) on pages 39-43, DOI: 10.11646/zootaxa.4622.1.1, http://zenodo.org/record/3379899