Manta

Marshall, Andrea D., Compagno, Leonard J. V. & Bennett, Michael B., 2009, Redescription of the genus Manta with resurrection of Manta alfredi (Krefft, 1868) (Chondrichthyes; Myliobatoidei; Mobulidae), Zootaxa 2301, pp. 1-28 : 20-22

Character key for Manta ( Fig. 15 )

(1) Pale to white-coloured shoulder patches present on dorsal supra-branchial region on each side of a

dark midline

Shoulder patches are very distinct and approximately triangular in shape with a posterior facing hook on the anterior distal side. Anterior edge of shoulder patches runs medially from spiracle in an approximately straight line parallel to the edge of the upper jaw ..................................................................................................................... Manta birostris

Anterior margin of shoulder patch initially emanating posteriorly from spiracle before curving medially. Towards the midline, colouration again begins to radiate out posteriorly continuing down over the supra-branchial region in variably sized and shaped shoulder patches. Anterior distal side of the shoulder patch may present as an anterior facing hook......................................................................................................................................................... Manta alfredi

(2) Ventral colouration and natural markings

Distinctive dark spots located on the ventral surface of disc over abdominal region, with no spots present medially between the five adjacent gill slits. Prominent semi-circular spot extends posteriorly from both of the most posterior gill slits. Charcoal-coloured margin typically present on posterior edges of pectoral fins that extend the entire length of each pectoral fin................................................................................................................................ Manta birostris

Distinctive dark spots on the ventral surface of disc can be present across the posterior half of the body and medially between the five adjacent gill slits. Small semi-circular spot extends posteriorly from of both of the most posterior gill slits.................................................................................................................................................... Manta alfredi

(3) Caudal spine

Caudal spine mostly encased in a calcified mass present on the dorsum of the tail immediately posterior to the dorsal fin ............................................................................................................................................................. Manta birostris No distinct, removable caudal spine or calcified mass present on tail........................................................... Manta alfredi

(4) Skin and dermal denticles

Skin, which forms distinct, sagittally oriented, ridges and furrows along the entire length of the dorsal and ventral surfaces, is densely embedded with overlapping, multicuspid denticles................................................... Manta birostris Skin on both dorsal and ventral surfaces embedded with small non-overlapping, evenly spaced denticles with stellate bases and laterally elongated knob-like (lacking cusps) structures projecting from skin....................... Manta alfredi

(5) Mouth colouration and dentition

Mouth black to charcoal grey in colouration. Dark colouration around mouth often extends posteriorly on the ventral surface from the base of the cephalic fins to the anterior edge of the first gill slits. Dental ligament embedded with small cusped teeth on the lower jaw measuring roughly 25% of total disc length with approximately 12–16 rows, 220–250 files across entire width of the band. Total tooth counts of 3000–4000 for entire tooth band. Upper jaw contains at least two rows of enlarged denticles that span the same width of the upper jaw as the tooth band on the lower jaw.... .............................................................................................................................................................. Manta birostris

Mouth is white to light grey in colouration. Dental ligament with small cusped teeth on the lower jaw measuring roughly 22% of total disc length with approximately 6–8 rows, 142–182 files across entire width of the tooth band. Total tooth counts of 900–1500 for entire tooth band. Upper jaw lacks rows of enlarged denticles............... Manta alfredi

Figures

FIGURE 15. Key features used to differentiate Manta birostris and Manta alfredi in the field: (1) presence, colour and shape of supra-branchial shoulder patches (2) ventral spot distribution and colouration (3) presence or absence of caudal spine (4) appearance of skin and denticle morphology (5) colour of mouth and dentition.