Thomontocypris lobodonta (Maddocks 1969)

Propontocypris (Propontocypris) lobodonta

Species DE [part] Maddocks, 1966, p. 50.

ETYMOLOGY.—Greek: lobos, rounded projection; odous, tooth.

TYPE-SPECIMENS.—Holotype USNM 121115, allotype USNM 121116, paratypes USNM 121117-121121, 121250.

TYPE-LOCALITY.—Nosy Bé, Madagascar, sample 196 (washings of Enteromorpha-like alga growing at low tide at Ambariobe).

DIAGNOSIS.—Carapace smooth, moderately inflated, greatest height and greatest thickness located slightly anterior to midlength. Dorsal margin in lateral view highly arched and angulate, narrowly rounded posteroventral angle located below one-fifth height, anterior margin very broadly rounded; females much smaller than males. Muscle-scar pattern an orderly arrangement of five scars in three horizontal rows, topmost scar not divided. Carapace of preserved specimen translucent white with short golden setae, body and appendages yellow, thick chitinous structures dark brown.

Mandible with stout multilobed teeth on the basal part, of the structural type found in the Paracyprididae, Macrocyprididae, and Bairdiidae; basal podomere of palp with three long annular feathered setae and one short simple seta, ventrodistal claw of podomere-2 and all distal claws of endopodite of annular and feathered structure. Maxilla with dorsomedian seta of basal podomere of palp pulmose, first and second masticatory processes each with two setae thickened and sparsely feathered, four setae slender and simple; third masticatory process with two setae thickened and abundantly feathered, two thick and simple, one short and simple. Palp of first thoracic legs of male with slender curved terminal hook; asymmetric peg on basal podomere, elongate and digitiform on one leg, short and nodular on the other. Second thoracic leg with dorsolateral mane of about ten fine setae at knee joint; podomeres-3 and -4 each with thick posteromarginal mane of short hairs, suture at their junction unusually distinct and perhaps movable, distal setae of each unusually long; terminal claw finely but distinctly pectinate. Pectinate seta of third thoracic leg very stout with regularly diminishing barbs; simple tapered seta five-fourths as long and one-half as thick as pectinate seta; triangularly spatulate seta four-fifths as long and one-fourth as thick as pectinate seta; slightly shorter and thinner, flexible, distally bladed seta. Furca with proximal claw twice as long and thick as distal claw, both distally barbed; distal seta tiny and half as long as distal claw, median and proximal setae of graduated length, thickly pectinate, median seta twice as thick as proximal setae. Copulatory organ of male arcuate, oblong, distally blunt and wrinkled in outline; copulatory tube short, straight and horizontal; vas deferens narrow. Testes confined to simple loop in posterior part of carapace.

MATERIAL.—Nosy Bé: 24 living specimens, 684 subfossil specimens. Grand Comoro Island: Two living specimens, eight subfossil specimens.

DIMENSIONS.—Adult male specimen USNM 121115 from Nosy Bé: left valve, length 0.90 mm, greatest height 0.52 mm, located 0.41 mm from anterior, thickness 0.22 mm; right valve, length 0.92 mm, greatest height 0.52 mm, located 0.41 mm from anterior, thickness 0.23 mm.

Adult female USNM 121116 from Nosy Bé: left valve, length 0.72 mm, greatest height 0.46 mm, located 0.37 mm from anterior, thickness 0.25 mm; right valve, length 0.79 mm, greatest height 0.47 mm, located 0.36 mm from anterior, thickness 0.21 mm.

Adult male specimen USNM 121118 from Grand Comoro Island: left valve, length 0.87 mm, greatest height 0.50 mm, located 0.40 mm from anterior, thickness 0.24 mm; right valve, length 0.89 mm, greatest height 0.51 mm, located 0.41 mm from anterior, thickness 0.24 mm.

HABITAT.—Nosy Bé: infrequent in washings of Enteromorpha-like algae from low tide level, of corals from the sublittoral zone, and in coralline sand from low tide level to 15 m depth. Grand Comoro Island: carbonate sand near coral reefs at about 70 feet depth.

SUBFOSSIL DISTRIBUTION.—Nosy Bé: extremely abundant in fine carbonate mud in the Lac du Cratère and from the front slope of the Sambirano River delta at 10–20 m depth; moderately abundant in shallow-water sands and sandy muds of all types, also present in intertidal beach sands and carbonate reef sands. Abundance appears to be dependent on nearby source of supply in reef or littoral zone and low energy sedimentary environment. Grand Comoro Island: carbonate reef sand.

DISTRIBUTION.—Collected in sediment from 55, 73, and 110 m depth off Mozambique.