Homestios janinecairae, Warren & Bullard, 2021

Warren, Micah B. & Bullard, Stephen A., 2021, Fish blood flukes (Digenea: Aporocotylidae) from Indonesia: Two new genera and species infecting the banded eagle ray, Aetomylaeus nichofii (Bloch and Schneider, 1801) Capape´and Desoutter, 1979 (Myliobatiformes: Myliobatidae) from Borneo, International Journal for Parasitology: Parasites and Wildlife 15, pp. 43-50 : 47-49

3.4. Homestios janinecairae n. sp. ( Figs. 3–4 )

3.4.1. Description of adult (based on a single whole-mounted specimen; USNM coll. no. 1642774)

Body 1305 long, 153 at greatest width, 9 × longer than wide ( Fig. 3 ), muscular, tapering gradually until bluntly rounded. Nerve commissures not evident in whole-mount. Ventrolateral nerve-cords located 13 from lateral body margin, 5 in maximum width, becoming confluent posteriorly, 8 from posterior body margin. Anterior sucker, aspinous, centered on mouth. Mouth 3 in diameter, 3 from terminal end of body ( Fig. 3 ). Oesophagus 408 in total length or 31% of body length, 18 in maximum width ( Fig. 3 ). Caecal bifurcation 163 or 12% of body length from anterior body end; caeca extending posteriad in parallel, asymmetrical, dextral caecum 153 long or 11% of body length, sinistral caecum 178 long or 14% of body length, 22 in mean width or 14% of body width ( Fig. 3 ); post-caecal space 765 long or 59% of body length ( Fig. 3 ).

Testicular mass 363 long or 28% of body length, 103 wide, occupying 67% of body width, 4 × longer than wide, dorsal to caeca, curving 33 times ( Fig. 3 ), narrowing and becoming confluent with vas deferens. Post-testicular space 418 long or 32% of body length. Vas deferens 181 long or 71% of seminal vesicle length, 4 wide, emanating from postero-ventral portion of testis, meandering sinistral to ovary and posteriad between ascending and descending uterine portions before connecting to the cirrus sac ( Figs. 3 and 4 ). Cirrus-sac having thin wall 1 thick, including seminal vesicle and cirrus; seminal vesicle extending sinuously posteriad, 258 long or 20% of body length, 20 wide or 13% of body width, 13 × longer than wide, running between ascending and descending portions of the uterus, curving 6 times ( Figs. 3 and 4 ), narrowing and curving sinistrally towards body margin ( Figs. 3 and 4 ); cirrus short, 10 long or 3% of seminal vesicle length, 8 wide, cirrus pore 5 in diameter ( Fig. 4 ). Common genital pore 120 or 9% of body length from posterior end of the body, 18 from sinistral body margin, 75 from dextral body margin ( Figs. 3 and 4 ).

Ovary medial, small, irregular in shape, not extending lateral to nerve cords, 38 long or 2% of body length, 70 wide or 46% of body width, 2 × wider than long; post-ovarian space 380 long or 29% of body length ( Figs. 3 and 4 ). Oviduct, vitelline duct, and o¨otype indistinct. Laurer’ s canal not observed. Ascending uterus 318 long, 15 in maximum width ( Fig. 4 ), extending anteriad arching dorsally over medial portion of vas deferens before connecting to descending portion; descending uterus extends posteriorly 238 long or 75% of ascending uterus length,

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13 in maximum width; post-uterine space 75 long or 6% of body length ( Fig. 3 ). Uterine eggs13 long, 6 wide or 46% of uterus width, containing many small dense bodies, with thin shell ( Fig. 4 ). Excretory vesicle 8 long, <1 wide, with arms ( Fig. 3 ).

3.4.2. Taxonomic summary

Type and only reported host: Banded eagle ray, Aetomylaeus nichofii (Bloch and Schneider, 1801) Capape´and Desoutter, 1979 ( Myliobatiformes : Myliobatidae ).

Site in host: Heart lumen.

Type locality: Off Takisung , Java Sea, (03 ◦ 52 ′ 28.00 ′′ S, 114 ◦ 36 ′ 37.00 ′′ E), South Kalimantan, Borneo, Indonesia .

Prevalence and intensity of infection: 1 (prevalence = 100%) banded eagle ray sampled on 2 December 2006 was infected by 1 specimen of H. janinecairae .

Specimens deposited: Holotype ( USNM 1642774 ).

Etymology: The specific epithet “ janinecairae ” honors Prof. Janine N.

Caira (University of Connecticut, Storrs, Connecticut USA) for her contributions to our knowledge of elasmobranch parasites .

3.4.3. Taxonomic remarks

Homestios janinecairae is most similar to M. richardheardi and all other nominal fish blood flukes infecting batoids (except G. bulbosus and A. kirstenjensenae ) by the combination of having an aspinous, diminutive anterior sucker, an asymmetrical inverse U-shaped intestine, a curving testis, and a post-caecal common genital pore as well as by lacking any spine along the lateral tegument ( Madhavi and Hanumantha Rao, 1970; Bullard and Jensen, 2008; Cutmore et al., 2018; Warren and Bullard, 2019; Warren et al., 2020). It differs from M. richardheardi by the combination of having> 30 testicular curves (vs. 9–10), a vas deferens that is> 70% of the seminal vesicle length, a seminal vesicle that curves 6 times (vs. 9–10), and a uterus that extends anteriad beyond the level of the seminal vesicle (KEY) ( Bullard and Jensen, 2008). Homestios janinecairae differs from all other fish blood flukes infecting batoids (except

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G. bulbosus and A. kirstenjensenae ) by having a body 9 × longer than wide, an oesophagus that is 1/3 of body length,> 30 testicular curves, a vas deferens that is> 70% of the seminal vesicle length, a sharply curved seminal vesicle that is 1/5 of body length, a cirrus that is <5% of seminal vesicle length, an ovary that is wider than long, and a uterus that extends anteriad beyond the level of the seminal vesicle (KEY). The only other species to have a uterus that extends anteriad beyond the level of the seminal vesicle is O. heterovitellatum and O. glaucostegi ( Madhavi and Hanumantha Rao, 1970; Cutmore et al., 2018). Orchispirium heterovitellatum is unique by having lateral tubercles along the tegument, posterior caeca that extend into the posterior half of the body, and a testis that is intercecal and bearing lobes along the margin ( Madhavi and Hanumantha Rao, 1970). The new species differs from O. glaucostegi by having a uterus that extends anteriad beyond the terminal margin of the testis (vs. remaining posterior to the ovary) before folding ventrally and continuing posterior to the common genital pore. Further, O. glaucostegi , E. zappum , and A. testisinuosus differ by having a body that is> 15 × longer than wide (vs. 9 in the new species and M. richardheardi ) (KEY) (Cutmore et al., 2019; Warren and Bullard, 2019; Warren et al., 2020).

KEY. Key to the identification of fish blood flukes (Digenea: Aporocotylidae ) infecting chondrichthyans

1a. Body spinous, lateral tegumental spines (LTSs) 2

C-shaped

1b. Body aspinous 8

2a. Intestinal caeca X-or H-shaped 3

2b. Intestinal caeca inverse U-shaped 5

3a. Oviducal ampullae present; ootype ¨posterior to Aetohemecus kirstenjensenae n. all genitalia gen, n. sp.

3b. Oviducal ampullae absent; o¨otype anterior to 4

common genital pore

4a. Body minute (<1.4 mm long), LTSs numbering Selachohemecus olsoni

> 170 per side of body

4b. Body large (≥ 1.4 mm long), LTSs <100 per side Selachohemecus benzi of body

5a. LTSs distributed in a single column, large Gymnurahemecus bulbosus oesophogeal bulb present

5b. LTSs distributed in multiple columns or lateral 6

field

6a. Caeca short, terminating at level of genital pores Chimaerohemecus trondheimensis

6b. Caeca elongate, terminating posterior to 7

genitalia

7a. Body 2 × longer than wide, mid-body LTSs <20 Hyperandrotrema cetorhini

μm long

7b. Body 7–8 × longer than wide, mid-body LTSs Hyperandrotrema

≥ 25 μm long walterboegeri

8a. Body margin having lateral tubercles Orchispirium heterovitellatum 8b. Body margin lacking lateral tubercles 9

9a. Body minute (<1 mm long), testis curving <15 Myliobaticola richardheardi times

9b. Body elongated, testis curving> 15 times 11

11a. Testis curving <50 times 12

11b. Testis curving> 50 times 13

12a. Seminal vesicle> 40% of body width; uterus Electrovermis zappum not extending anterior to seminal vesicle

12b. Seminal vesicle <20% of body width; uterus Homestios janinecairae extending anterior to seminal vesicle

13a. Testis curving <80 times; uterus extending Ogawaia glaucostegi anterior to posterior margin of testis

13b. Testis curving> 100 times; uterus wholly Achorovermis testisinuosus posterior to ovary

Figures

Fig. 3-4. Homestios janinecairae Warren and Bullard n. gen., n. sp. (Digenea: Aporocotylidae) from the heart of the banded eagle ray, Aetomylaeus nichofii (Bloch and Schneider, 1801) Capape´and Desoutter, 1979 (Myliobatiformes: Myliobatidae). (3) Body of holotype (USNM No. 1642774), dorsal view. Bar = 250 μm. (4) Genitalia of holotype (USNM No. 1642774), dorsal view. Bar = 100 μm. Mouth (mo), oesophagus (os), vitellarium (vit), intestine (in), testis (t), ovary (ov), vas deferens (vd), uterus, (u), ascending uterus (au), descending uterus (du), seminal vesicle (sv), cirrus (c), and common genital pore (cgp).