Hexangium saudii, Al-Jahdali & O, 2013
publication ID |
https://doi.org/ 10.5281/zenodo.5732120 |
persistent identifier |
https://treatment.plazi.org/id/A166879C-1B07-FF82-D39B-C6D9FD95FA44 |
treatment provided by |
Felipe |
scientific name |
Hexangium saudii |
status |
sp. nov. |
Hexangium saudii View in CoL sp. n.
( Fig. 1 View Figs 1–2 )
Type- host: Siganusrivulatus ForsskåletNiebuhr (Teleostei, Siganidae ).
Site: Middleintestine.
Type- locality: RedSeaoffthecoastofRabigh (between 22°49′Nand 22°54′N), SaudiArabia. Prevalence: 8/40 fishesexamined; 20%.
Type- material: HolotypeandparatypesaredepositedintheNaturalHistoryMu-
seum, London, Reg. nos. 2011.8.2.1 and 2011.8.2.2–8.
Description (Basedon 10 fullygravidspecimens): Bodylanceolateorelongate- pyri- form, stout, somewhatdorso- ventrallyflattened, 2,261 –3,551 (2,906) inlength, 648–1,019 (834) inmaximumwidthinitsposteriorthird. Tegumentarmedwithfinesharpspines dorsallyandventrally (oftenlostduringfixation). Suckersabsent. Pharynxsub-terminal, globular, welldeveloped, directlysurroundsoralopening, 152–238 × 143–225 (195 × 184). Oesophaguslong, 529–831 (680), providedwithroundoesophagealbulbatitsposterior end; bulbsmall, 74–118 (96) indiameter. Intestinalbifurcationataboutjunctionoffirstand secondthirdsofbody; caecadistinctlyshort, wide, extendintomiddlethirdofbody. Testes 2, usuallyoval, sometimesround, situatedobliquelyinposteriorregionofbody, subequal, 260–408 × 232–366 (334 × 299). Cirrussacabsent. Seminalvesicleelongate, slender, extends anteriorlyfromshortdistanceposteriortointestinalbifurcationtonearthegenitalpore, 350–568 × 42–62 (429 × 52); distalendofvesiclejoinsthatoftheuterustoformrelatively shorthermaphroditicduct. Genitalporesituatedmid- waybetweenpharynxandintestinal bifurcation. Ovaryround, median, immediatelypost-testicular, neartoposteriorextremity, 119–183 (151) indiameter. SeminalreceptacleandLaurer’scanalabsent; uterineseminalre- ceptaclepresent. Uterusrelativelylong, coiledintesticularregionandbetweentestesand intestinalcaeca, thenpassesdirectlybetweencaecatogenitalpore. Eggsoval, yellowish, thick-shelled, moderatelylarge, 56–66 × 38–46 (61 × 42). Vitellinefolliclesmoderatelylarge, arrangedin 5–7 rosette- likegroupsoneachside, extendinglateraltocaecaforalmosttheir entirelength. ExcretoryvesicleV-shaped; excretoryarmsdividenearposteriorendofeach caecum, givingriseto 3 longcollectingductsextendinganteriorlytonearlevelofgenital pore. Excretoryporedorso- subterminal.
Comment – Hexangium GotoetOzaki, 1929 currentlyincludestwovalid species, H. sigani GotoetOzaki, 1929 and H. brayi HassanineetGibson, 2005 . Thefirstisthebestknown, sinceithasbeenrecordedinnumeroussiganid species (VELAsquEz 1961, FIscHtHAL & Kuntz 1964, 1965, AL-YAMAnI & NAH- HAs 1981, GEEts & OLLEvIEr 1996, KArDOusHA 2003, SEy etal. 2003, DzIkOwskI etal. 2003, EL-LAbADI etal. 2006), whereasthesecondisknownonlyfromits originaldescription.
Theabovedescriptionof H. saudii sp. n. agreeswiththeconceptof Hexangium GotoetOzaki, 1929 . However, itclearlydiffersfromthetwoknownspe- ciesofthegenus, beinguniqueinhavingthefollowingtwocharacters:
− Theintestinalcaecaaredistinctlyshort, extendingonlytothemiddle thirdofthebodyandaremoredistantfromthetestes (versuslongand extendingtoclosetothetestes).
− Thevitellinefolliclesarearrangedinrosette- likegroups (versusarranged singlywithoutacharacteristicappearance).
However, thenewspeciesdiffersfromeachoftheothertwospeciesof thegenusinseveralotherspecificcharacteristics: from H. sigani inhaving vitellinefolliclesonlydistributedlateraltothecaeca (versusdistributedlat- eralandmedialtothecaeca) andinhavingsmallereggs (56–66 × 38–46 μm) (versus 77–85 × 50–56 μm); andfrom H. brayi inhavingadistinctlysmaller oesophagealbulb, obliquelyarrangedtestes (versussymmetricallyarranged), vitellinefolliclesdistributedlateraltothecaeca (versusconfinedtotheintercaecalfield) andsmallereggs (56–66 × 38–46 μm) (versus 70–85 × 55–60 μm). Inviewofthesespecificdifferences, thepresentspeciesisconsideredtobe newtoscience.
Etymology: Thespecificname “ saudii ” ofthenewspeciesreferstothelocalityoffthe
coastofSaudiArabia.
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