Taxonomy & naming
Allotoca maculata was described by Ralph G. Smith and Robert Rush Miller in 1980, in Copeia, from material collected in western Mexico — the holotype a mature male of 1 in standard length taken by Miller and J. M. Fitzsimons in February 1970 at Laguna Magdalena, Jalisco, roughly 51 mi west of Guadalajara. The type series included paratypes from Hacienda San Sebastián near Etzatlán. Eschmeyer's Catalog of Fishes treats Allotoca maculata Smith & Miller, 1980 as the valid name, placing the species in the genus Allotoca within the subfamily Goodeinae of the family Goodeidae — the splitfins or goodeids, the live-bearing toothcarps of the Mexican highlands.
The genus name Allotoca derives from the Greek allos, "other" or "different," combined with tokos, "birth" or "offspring," a reference to the distinctive trophotaeniae — the ribbon-like umbilical structures — through which goodeid embryos are nourished inside the female. The specific epithet maculata is Latin for "spotted," naming the dark basicaudal blotch that distinguishes the fish, the same mark behind its English name, blackspot allotoca, and the Spanish tiro manchado. Within Allotoca, A. maculata is regarded as the most basal species in the genus, and modern work recognises two evolutionarily significant units — one in the endorheic Lake Magdalena system, the other in the San Marcos / Río Ameca drainage.
Morphology
Allotoca maculata is a small splitfin, reaching about 2.5 in total length in males and around 3 in in females after Wischnath's livebearer atlas, though Miller's 2005 treatment cites a maximum of roughly 2 in standard length. The body is small, deep and laterally compressed, with the dorsal and anal fins set well back along the body — though less posteriorly placed than in its relative A. dugesii. Predorsal length runs to about 64–68 percent of the body, the dorsal fin carries 13–14 soft rays and the anal 11–13, and there are 28–32 scales in the lateral series. Mandibular pores are absent. The diploid chromosome number is 48.
The species is sexually dimorphic in both colour and fin shape. The fins of males are longer, more rounded and elevated than those of females. Females carry three to six iridescent-blue blotches along the flank, while males show a lateral series of fine dark spots; both sexes bear one or more dark spots on the caudal peduncle — the basicaudal "maculata" mark for which the fish is named. As goodeids, males do not develop the rod-like gonopodium of New World poeciliids; instead the first six or seven anal-fin rays are shortened and separated from the rest by a notch, forming the andropodium or spermatopodium characteristic of the splitfins.
Habitat
Allotoca maculata is endemic to Jalisco, Mexico, restricted to the endorheic Laguna Magdalena basin together with Arroyo Chacuaco, Laguna El Palo Verde and the Canal del Bajío of the Río San Marcos, which drains toward the Río Ameca. It is a fish of shallow lake margins and cienegas — spring-fed marshes — living in clear-to-muddy water over soft mud substrate, typically at depths under half a metre. Aquatic vegetation including water hyacinth (Eichhornia crassipes) and Hydrocotyle is a feature of its waters, and the fish can survive the dry season in shrinking, vegetated, standing water along the lake edge.
Field measurements give a sense of how cool these highland waters run: late-afternoon temperatures of 60 °F in late February 1957 and 61 °F in February 1970 were recorded at collection sites, somewhat warmer at other seasons. The native range has contracted sharply. The species has not been found in the Río Ameca system since around 2000, is now scarce in Laguna Magdalena itself, and persists best around the Palo Verde lagoon. Both of its recognised lineages — the Lake Magdalena unit and the San Marcos unit — are in decline, pressed by water pollution, water scarcity, habitat destruction and introduced non-native fishes.
Feeding
Allotoca maculata is a carnivore. Its dentition — conical teeth with an enlarged outer row — paired with a short gut marks it out from the more herbivorous goodeids, and it feeds on small to mid-sized invertebrates: bloodworms and other insect larvae, water fleas, mysids and similar prey taken among the soft mud and vegetation of its shallow habitats. Its trophic level is estimated at around 2.2, consistent with a diet built mainly on small animal prey.
In the aquarium the species accordingly does best on a protein-forward, invertebrate-rich diet. Live and frozen foods such as bloodworms, Daphnia and brine shrimp suit it well, supplemented by good-quality prepared foods. As with most splitfins, clean water and frequent feeding in modest amounts support both condition and the demanding live-bearing reproduction these fishes undertake.
Mating
Like all goodeids, Allotoca maculata practises internal fertilisation, but its anatomy differs from that of the more familiar poeciliid livebearers. There is no gonopodium; instead the male's anal fin is modified into the splitfin andropodium, in which the first roughly seven rays are shortened and set off by a notch from the remainder of the fin. This crowded, partly separated front lobe of the anal fin is used in the transfer of sperm bundles to the female during a brief mating contact rather than the prolonged or sneaky copulations of guppies.
Reproduction is seasonal in the wild. Pregnant and gravid females have been collected in late February (1970) and again in October (2018), when nearly all females sampled were gravid and judged to be within about two weeks of giving birth. In captivity the species spawns at around 68–70 °F and tends to stop if kept too warm, near 77 °F — behaviour that mirrors the cool highland waters it comes from and sets it apart from most of its warmer-water relatives in the genus.
Breeding
Allotoca maculata is viviparous, and like other members of the Goodeinae it is matrotrophic: the developing embryos are nourished by the mother throughout gestation, not merely supplied by yolk. The young develop trophotaeniae — external, ribbon- or rosette-like structures extending from the vent that act as a placental analogue, drawing nutrients from the maternal reproductive tract. This is a fundamentally different reproductive strategy from the lecithotrophic, yolk-fed live-bearing of poeciliids, and it is the trait the genus name Allotoca itself commemorates. Brood sizes in goodeids are modest by livebearer standards and the fry are large and well developed at birth; superfetation — carrying overlapping broods at different stages — is not a feature of this species in the way it is in some poeciliids, the detailed brood data here being sparse.
In the aquarium, breeding tracks the cool, seasonal cues of the wild fish. Spawning occurs at about 68–70 °F and ceases as temperatures climb toward 77 °F; keepers deliberately impose a winter rest below 68 °F for two to three months to pause fry production and rest the females, mimicking the natural cycle. The species is described as warmer-tolerant than most other Allotoca, with a recommended minimum winter temperature of about 63 °F. A captive studbook for the species has been maintained by Austrian aquarists within the OVVO's Allotoca Mesa Central conservation programme, making this one of the goodeids whose survival is most closely tied to organised hobbyist breeding.
In the aquarium
Allotoca maculata is a specialist's fish rather than a beginner's livebearer, kept today largely within conservation-breeding circles. It needs a roomy tank with a large footprint and low height — on the order of 25 US gal with a height around 10 in — reflecting its origin in shallow lake margins. It demands well-oxygenated water (dissolved oxygen of 8 mg/L or more), moderate current and very clean conditions, with large weekly water changes of 60–80 percent. Water chemistry should be neutral to slightly alkaline and moderately hard, in keeping with its native springs (pH about 7.0–7.7, dH 5–20).
Temperature management is the crux of keeping this species. It is warmer-tolerant than most Allotoca but still a cool-water fish: a minimum winter temperature near 63 °F, spawning around 68–70 °F, and a deliberate winter rest below 68 °F for two to three months. Sustained warmth near 77 °F halts breeding and stresses the fish. Given its Critically Endangered status and its near-total dependence on captive lines, anyone keeping it should treat it as a conservation responsibility — sourcing studbook stock, recording lineages and maintaining the cool seasonal regime that keeps the population reproducing.
Conservation
Allotoca maculata is assessed as Critically Endangered on the IUCN Red List (criteria B1ab(i,ii,iii,iv)c(ii)+2ab(i,ii,iii,iv)c(ii)), under an assessment dated 18 April 2018. Both of its evolutionarily significant units are Critically Endangered and declining. The Lake Magdalena lineage has been hit by water pollution, habitat destruction and non-native species, and was not collected in over four years despite targeted surveys; the San Marcos lineage suffers from water scarcity, habitat loss and introduced fishes, and persists only in small numbers at one or two locations. The status review of Mexican Goodeidae by Lyons and colleagues (2019) documents this decline in detail. Under Mexico's NOM-059-SEMARNAT-2010 the species carries no risk category, and it is not evaluated by CITES.
The threats are the familiar ones facing the goodeids of the Mexican Central Plateau: the drying and pollution of endorheic basins, the conversion and degradation of cienega habitat, and competition and predation from introduced species. With its native waters failing, the species' continued existence leans heavily on ex-situ effort — notably the European studbook lines maintained through programmes such as the OVVO's Allotoca Mesa Central project. For the blackspot allotoca, organised conservation aquaculture is not an enrichment of the wild population but, increasingly, a hedge against its loss.