An egg mass fragment and one paralarva of the squid Thysanoteuthis rhombus found in the Northeastern Tropical Pacific and Gulf of California, Mexico are the first evidence of reproduction of this species in the region. The egg mass fragment was in the disintegration process and contained 30,360 premature hatchlings (96.2%) and 1,192 eggs (3.8%) at different developmental stages. Head chromatophore patterns, buccal crown pigmentation, arm and tentacles indexes, and other morphological characteristics complement previous descriptions of T. rhombus paralarvae. The zooplanktonic community associated with the egg mass was dominated by six species of predatory copepods of the genus Labidocera, Pontella, Oncaea, and Corycaeus which might have actively colonized the egg mass to feed upon the eggs and hatchlings.