Elasmobranchii (sharks and rays) > Pristiophoriformes
(Saw sharks) > Pristiophoridae
Etymology: Pliotrema: pleion (Gr.), more; trema (Gr.), hole, referring to six gill slits compared with five in Pristiophorus. (See ETYFish); annae: In honor of Anna Weigmann Huerta, the senior author’s niece, “to express its relationship” to P. kajae, named after the senior author’s daughter. (See ETYFish).
Environment: milieu / climate zone / depth range / distribution range
Marine; demersal; depth range 20 - 35 m (Ref. 122027). Tropical
Western Indian Ocean: Zanzibar and probably off Kenya and Somalia.
Size / Weight / Age
Maturity: Lm ?  range ? - ? cm
Max length : 98.0 cm TL (female)
Morphology | Morphometrics
This medium-sized six-gilled sawshark is distinguished by the following characters: barbel origin to anterior nostrils 1.9-2.0 times anterior nostrils to symphysis upper jaw; prenarial length 1.6-1.7 times prebarbel length; preoral length 1.5-1.7 times interdorsal space; pectoral-fin anterior margin 1.4-1.5 times dorsal-caudal space; mouth width 2.7-3.2 times spiracle length; the first dorsal fin originates about opposite pectoral-fin free rear tips; lateral trunk dermal denticles tricuspidate, rather flat and imbricated; monospondylous centra 53-54; precaudal diplospondylous centra 46-49; total vertebral centra 154; generally with a shorter snout, head length 34.2-34.5% TL, preorbital length 21.7-22.0% TL, preoral length 24.6-25.1% TL, prebarbel length 12.6-12.7% TL, and barbel origin to symphysis upper jaw 12.1-12.3% TL; with lower total large lateral rostral tooth and ventral rostral spine counts, and a rostrum that is slightly constricted between barbel origin and nostrils. Similar to P. kajae, with barbels situated about half way from rostral tip to mouth, with prebarbel length about equidistant from barbel origin to symphysis of upper jaw, while in P. warreni, the barbels are situated about two thirds way from rostral tip to mouth, with prebarbel length about twice distance from barbel origin to symphysis of upper jaw. Colouration: uniform medium to dark brown dorsally without longitudinal stripes; white ventrally but with few indistinct dark blotches on belly; fins with pronounced white posterior fin margins, especially the caudal and pectoral fins; dorsal rostrum surface with two distinct longitudinal dark stripes, lateral rostral teeth dark-edged (Ref. 122027).
Probably occurs in deeper waters during the day but enters shallow water during the night. The specimens were caught directly adjacent to a dropoff along the southern tip of Unguja Island where the water depth descends rapidly from ca.20 m to >200 m (Ref. 122027).
Life cycle and mating behavior
Maturity | Reproduction | Spawning | Eggs | Fecundity | Larvae
Weigmann, S., O. Gon, R.H. Leeney, E. Barrowclift, P. Berggren, N. Jiddawi and A.J. Temple, 2020. Revision of the sixgill sawsharks, genus Pliotrema (Chondrichthyes, Pristiophoriformes), with descriptions of two new species and a redescription of P. warreni Regan. PLoS ONE, 15 (3):1-56. (Ref. 122027)
IUCN Red List Status (Ref. 125652)
Threat to humans
Common namesSynonymsMetabolismPredatorsEcotoxicologyReproductionMaturitySpawningSpawning aggregationFecundityEggsEgg development
ReferencesAquacultureAquaculture profileStrainsGeneticsAllele frequenciesHeritabilityDiseasesProcessingNutrientsMass conversion
Estimates based on models
Phylogenetic diversity index (Ref. 82804
= No PD50 data [Uniqueness, from 0.5 = low to 2.0 = high].
Bayesian length-weight: a=0.00389 (0.00180 - 0.00842), b=3.12 (2.94 - 3.30), in cm total length, based on all LWR estimates for this body shape (Ref. 93245
Trophic level (Ref. 69278
): 4.0 ±0.6 se; based on size and trophs of closest relatives
Fishing Vulnerability (Ref. 59153
): High vulnerability (59 of 100).