Phidippus cardinalis

Phidippus cardinalis, commonly known as the cardinal jumper, is a medium to large jumping spider in the family Salticidae, endemic to North America and renowned for its striking red dorsal coloration on the carapace and abdomen, which serves as mimicry of velvety mutillid wasps (*Dasymutilla* spp.) to deter predators.^[1] Males typically measure 4.36–15.24 mm in body length, featuring a red dorsum accented by two black longitudinal stripes, weakly blue chelicerae, and a bifurcate tibial apophysis tip on the male palp, while females are slightly larger at 4.48–18.10 mm, with more variable red or brown dorsum patterns including white spots and a pale venter marked by three gray stripes.^[1] The epigynum in females is distinguished by parallel posterior flaps that are slightly concave medially and excavate anteromedially, with spermathecal ducts.^[1] This species belongs to the cardinalis group within the genus Phidippus, which comprises about 75 species characterized by their robust build and acute vision for hunting.^[1][2] It is distributed across the eastern and central United States, ranging from southern New England southward to Florida and westward to Colorado, New Mexico, and Texas, with outlying records in southern Mexico and Panama that may be erroneous.^[1][3] P. cardinalis inhabits xeric fields, prairies, old fields, and the herbaceous or shrubby understory of open woodlands, showing a preference for grassy areas near water in peninsular Florida.^[1] Behaviorally, it is an active visual predator that jumps to capture prey, with adults emerging in autumn in many regions—though year-round in southern Florida—where females overwinter and guard eggsacs laid in late fall or winter under bark or logs to protect against desiccation.^[1] Juveniles start pale yellow on dead grass, maturing to orange and then red, and males may cohabit with females post-mating.^[1] Notably variable in size and color across its range, P. cardinalis can reach nearly 20 mm in some Texas populations and is distinguished from similar species like P. apacheanus by the absence of bright green chelicerae in males.^[1][3]

Taxonomy

Classification

Phidippus cardinalis belongs to the kingdom Animalia, phylum Arthropoda, class Arachnida, order Araneae, infraorder Araneomorphae, family Salticidae, genus Phidippus, and species cardinalis.^[4][5] The binomial name Phidippus cardinalis was established by the American arachnologist Nicholas Marcellus Hentz in 1845, based on specimens from the southeastern United States.^[4] Within the genus Phidippus, which comprises 73 accepted species (as of 2024), P. cardinalis belongs to the cardinalis group and is recognized as one of the larger species in the genus.^[6][1] Phylogenetically, Phidippus cardinalis is nested within the diverse family Salticidae, which is distinguished by the evolutionary development of exceptional visual acuity among spiders, enabling complex vision-mediated hunting and social interactions.^[7]

Etymology and synonyms

The genus name Phidippus is derived from the Ancient Greek Pheidippos (Φείδιππος), meaning "one who spares horses" or "thrifty horse," a reference to the agile, leaping locomotion characteristic of jumping spiders in this group.^[8] The specific epithet cardinalis is a Latinized adjective referring to "cardinal," alluding to the species' prominent bright red coloration on the cephalothorax and abdomen.^[3] Phidippus cardinalis was originally described by Nicholas Marcellus Hentz in 1845 as Attus cardinalis in his work Descriptions and figures of the araneides of the United States, based on specimens from Alabama (holotype male destroyed).^[1] Hentz provided illustrations and noted its reddish hue and jumping behavior, distinguishing it from other Attus species.^[9] Over time, numerous synonyms have accumulated due to morphological variability and early taxonomic confusions, with many resolved in modern revisions. Key synonyms include:

• Attus rufus Hentz, 1846
• Plexippus rufus C. L. Koch, 1846
• Plexippus bivittatus C. L. Koch, 1846
• Attus mccookii Peckham & Peckham, 1883
• Phidippus ruber Keyserling, 1885 (in part)
• Phidippus aureopilosus F. O. Pickard-Cambridge, 1901
• Phidippus oaklandensis Tullgren, 1901

^[1][6] The nomenclatural history reflects broader reclassifications within the Salticidae family, where the species was initially placed in the genus Attus before transfer to Phidippus upon its establishment by C. L. Koch in 1846.^[6] Eugène Simon (1901) temporarily assigned it to Dendryphantes cardinalis, but subsequent works, including the comprehensive revision by G. B. Edwards (2004), confirmed its placement in Phidippus and synonymized earlier names to stabilize nomenclature, suppressing junior synonyms where necessary for clarity.^[1] These changes arose from genus-level rearrangements in jumping spiders, emphasizing cheliceral and genitalic characters for delineation.^[9]

Description

Adult morphology

Adult Phidippus cardinalis specimens are medium to large jumping spiders, with total body lengths ranging from 4.4 to 18.1 mm.^[1] Like other salticids, they exhibit a robust black cephalothorax with white scales laterally, red scales on the ocular quadrangle, and black vestitural setae, supporting the characteristic arrangement of eight eyes, and an ovoid abdomen often featuring a pattern of light spots and a median dark stripe overlaid with scales.^[1] The ocular quadrangle occupies 40–50% of the carapace length, with the large anterior median eyes providing stereoscopic vision for precise depth perception during prey detection; the PME row occupies 0.30–0.43 of the distance from ALE to PLE.^[1][10] The legs consist of four pairs, with the first pair notably stout and fringed; the leg formula is I–IV–II–III in males and IV–I–II–III in females. The tarsi bear scopulae—dense arrays of adhesive setae—that enable secure adhesion to smooth surfaces and facilitate controlled landings after jumps.^[1][11] These strong hind legs are adapted for propulsion, allowing jumps of up to 40 times the spider's body length.^[10] The chelicerae are robust and porrect, displaying an iridescent sheen ranging from yellow-green to blue-violet, and bear two promarginal teeth and one retromarginal tooth; the associated fangs are small and inject mild venom primarily for subduing prey.^[1] Human envenomations result in minor irritation comparable to a bee sting, with no medically significant effects.^[12] Silk glands produce dragline silk, which is deployed as a safety line during jumps to prevent falls and allow mid-air adjustments in trajectory.^[13]

Sexual dimorphism and color variations

Phidippus cardinalis exhibits pronounced sexual dimorphism, particularly in size and coloration, with males generally displaying more vibrant hues than females. Adult males typically measure 4.5–7.0 mm in body length on average, though specimens from Texas and Mexico can reach up to 15–20 mm, featuring a bright red or orange-red dorsum covered in scales, a black carapace, and iridescent, weakly blue chelicerae that enhance visual displays. The abdomen often includes white spots and a basal band, while the venter is pale or gray with white side stripes. In contrast, females are larger, averaging 5.5–9.0 mm but up to 18 mm in body length, with a red or occasionally brown dorsum adorned with variable white, yellow, orange, or red spots and bands for a more patterned appearance; the venter is pale with three gray stripes and white side stripes.^[1] Color variations are evident across life stages and regions, contributing to the species' adaptability. Immature spiders are cryptically colored, starting pale yellow and transitioning through orange to the adult red tones, with some developing orange spots that fade to white upon maturity. A rare brown morph occurs in females, providing enhanced camouflage against certain substrates. Regional differences include enlarged or fused dorsal spots in populations from the "Big Bend" region of Florida, and overall larger sizes with potentially more intense coloration in southwestern U.S. and Mexican individuals. These variations in spot size and fusion highlight intraspecific diversity.^[1][14] The dimorphism in coloration serves distinct ecological roles, with males' vibrant red and iridescent features primarily functioning to attract females during courtship displays, a common trait in salticids where brighter male ornamentation signals fitness. Females' more subdued patterns, including the brown morph, promote crypsis in grassy or xeric habitats, aiding concealment from predators. This sex-specific coloration aligns with broader patterns in jumping spiders, where male brightness evolves under sexual selection despite predation risks.^[1][15]

Distribution and habitat

Geographic range

Phidippus cardinalis is distributed across the eastern and central United States, ranging from southern New England, including Massachusetts and Connecticut, southward to Florida, and westward through Illinois, Colorado, New Mexico, and to Texas.^[3] The species also occurs in Mexico, with possible records from Panama. Recent confirmations have extended the known range to western and northern Colorado, beyond the core eastern distribution.^[3][16] The species was first described by Nicholas M. Hentz in 1845 from specimens collected in the southeastern United States, likely Alabama. Citizen science platforms such as iNaturalist have facilitated recent sightings and observations, aiding in mapping and verifying the species' presence across its range, including extensions in Colorado.^[17]

Habitat preferences

Phidippus cardinalis thrives in sunny, open environments such as grasslands, prairies, fields, and herb/shrub zones of open woodlands, favoring xeric (dry) sites including sandhills and dunelands that lack a dense canopy.^[18][1] These habitats provide the warm, exposed conditions essential for the spider's visual hunting strategy, with individuals often observed in areas like Florida's xeric fields and mixed forest-prairie edges.^[18] The species avoids shaded or densely forested areas, preferring lower strata in semi-xeric to xeric settings where sunlight facilitates prey detection.^[18] This jumping spider is commonly associated with grasses and low vegetation, including sandhill grasses and red-topped varieties, which offer perching sites for foraging and shelter in tufts.^[18][1] Younger instars utilize dead grass for concealment, while adults perch on plant stems, bushes, or low herbaceous layers to ambush insects.^[1] Such microhabitats support the spider's active hunting behavior, with records also noting occurrences on sidewalks and near buildings in suburban settings.^[18] The preference for these habitats reflects adaptations to environments rich in insect prey, as open, sunny areas attract flying arthropods suitable for salticid predation.^[18]

Behavior and ecology

Diet and foraging

Phidippus cardinalis is a carnivorous generalist predator that primarily consumes a variety of small insects, including flies, moths, and soft-bodied arthropods such as aphids.^[19] It also preys on larger insects like grasshoppers and katydids, particularly females which target items several times their body size.^[20] Occasionally, it feeds on other spiders and, in the absence of prey, supplements its diet with pollen and nectar.^[19] The foraging behavior of P. cardinalis is diurnal, with activity peaking from mid-summer to fall, during which individuals actively search for prey in vegetation such as tall grasses and weeds.^[21] They stalk stationary or slow-moving targets using their excellent vision before pouncing, often climbing stems in sunny, open habitats.^[19][20] As a generalist predator, P. cardinalis plays a key role in controlling pest populations in its habitats, helping to regulate numbers of agricultural and garden insects.^[19] This opportunistic feeding strategy allows it to thrive in diverse environments by targeting available prey up to approximately its body length, though females exhibit greater flexibility in handling larger items.^[20]

Predatory strategies

Phidippus cardinalis, like other salticids, is an active visual hunter that relies on its exceptional eyesight to locate and pursue prey. The species possesses eight eyes, with the two large anterior median principal eyes providing high-acuity color vision for close-range assessment and the secondary eyes enabling motion detection across wider fields from distances up to approximately 30 cm; these principal eyes enable the spider to orient its body for binocular focus, often tilting its head to better assess potential targets at close range (10–30 mm), a behavior that aids in evaluating prey motility and distance.^[18][22][23] Hunting typically begins with stalking, where P. cardinalis either ambushes from perches on plant stems, scanning for movement below, or actively searches along foliage, using its forelegs to probe and sense the environment tactilely. Approaches are circuitous to avoid alerting prey, with attacks launched from close range—such as 10–12 mm for larval prey or 25–30 mm for flies—following careful visual evaluation of the target's behavior. This strategy minimizes escape risks and is adapted to diverse prey, including insects like grasshoppers that the spider stalks deliberately.^[18][19][22] The culminating jump attack utilizes hydraulic pressure in the legs to propel the spider up to 25 times its body length, potentially covering 15–50 cm for adults measuring 8–15 mm. During the leap, P. cardinalis extrudes a silk dragline from its spinnerets as a safety tether, which stabilizes orientation, prevents falls, and allows retrieval to the starting point if the pounce misses. This silk also facilitates precise landings, reducing recovery time for subsequent pursuits.^[24][22] Post-capture, the spider immobilizes prey by injecting venom via its fangs, followed by the extrusion of digestive enzymes that liquefy internal tissues for direct consumption through sucking. Unlike web-building spiders, P. cardinalis does not wrap prey in silk for storage, instead feeding immediately to exploit fresh nutrients. These adaptations, including the principal eyes' sensitivity to motion and the hydraulic jumping mechanism, underscore the species' efficiency as a diurnal predator in its habitat.^[18][22]

Mimicry and defense

Phidippus cardinalis exhibits Batesian mimicry, resembling velvet ants (Dasymutilla spp.) in body size, coloration, and fuzzy texture to deter predators that avoid stinging Hymenoptera. Adults measure 8–15 mm in length, aligning closely with the 6–25 mm range of many Dasymutilla species, while the red and black scales on males create a warning-like appearance akin to the aposematic patterns of these wasps.^[18][14][25] This mimicry reduces predation risk, as evidenced by laboratory tests where lizards (Anolis carolinensis and Sceloporus undulatus) avoided models of similar mimetic jumping spiders such as P. apacheanus, likely due to learned aversion from encounters with noxious velvet ants; males' brighter red hues amplify this signal for greater deterrent effect.^[18] Additional defenses include a threat posture involving raised forelegs to intimidate approaching threats, leg autotomy to break free if seized by predators, and reliance on exceptional agility for rapid jumps rather than web construction.^[26][27][28] The evolution of this mimicry is tied to open, xeric habitats like sandhills and pine scrubs in the eastern United States, where P. cardinalis co-occurs with Dasymutilla species, fostering selection for protective resemblance amid shared predators such as lizards and birds.^[18][14]

Reproduction and life cycle

Mating and courtship

Males of Phidippus cardinalis engage in visual courtship displays typical of the genus Phidippus, holding their forelegs (legs I) high and close to the body, with single or double flicks that raise and inward-direct the forelegs, causing the tarsi to touch or cross, interspersed with pauses of 5-6 seconds.^[18] When approaching a female within her nest, males may switch to a vibratory or tactile courtship, though details are limited due to observational challenges.^[18] The bright red coloration of males, more pronounced than in females, enhances visibility during these rituals and contributes to their attractiveness.^[29] Males actively search for mates during the adult season from late spring through fall, primarily relying on their acute vision rather than pheromones to locate receptive females in shared habitats like xeric fields and woodlands. Males may cohabit with subadult or adult females, potentially as a strategy to mate when the female is weakened after egg-laying.^[29][18] Courtship success depends on the vigor and precision of displays, with females assessing male performance to select mates, a process that underscores sexual selection in the species.^[19] Sexual cannibalism poses a risk during courtship, particularly if displays fail to appease the female, though it appears infrequent in P. cardinalis compared to other salticids; males often retreat rapidly post-mating to avoid predation.^[18] In related Phidippus species, females occasionally attack smaller males during interspecific encounters, indicating potential size-based vulnerabilities.^[18]

Egg laying and development

Following mating, female Phidippus cardinalis produce one or more egg sacs containing tens to hundreds of eggs typical of the genus, typically deposited within a silken retreat such as under bark, rocks, or a folded leaf or grass tuft for protection, often with added silk to prevent desiccation.^[18][1] These sacs are constructed in concealed locations to minimize predation risk, with clutch size influenced by female body length according to observed patterns across the genus (regression: clutch size ≈ 18.28 × female length in mm – 95.05).^[18] The female guards the egg sac until the spiderlings emerge and disperse, typically over several weeks.^[30] Eggs hatch after approximately 3 weeks.^[31] Upon emergence, the spiderlings undergo 6–8 molts over several months to reach maturity, progressing through instars where they develop the characteristic red coloration of adults, starting with first instars having black bodies and pale yellow distal leg segments, then pale yellow, orange, and red in later juveniles.^[18][1] Dispersal occurs primarily on foot rather than via ballooning, which is rare in salticids; the young scatter locally to avoid competition and predation.^[18] Egg laying in P. cardinalis typically occurs from late winter to early spring in southern ranges, aligning with adult maturation primarily in late summer to autumn and activity through fall in northern areas, with spiderlings overwintering as subadults before maturing the following season.^[30][1] This timing ensures synchronized development with seasonal prey availability.^[18]

Lifespan and growth stages

Phidippus cardinalis exhibits an overall lifespan of 1 to 2 years in natural conditions.^[32] Males typically reach maturity faster than females, maturing in approximately 6 to 9 months from egg hatch, though their post-maturity lifespan ranges from 3 to 8 months.^[18] In contrast, females live longer after maturation, with post-maturity durations of 5 to 12 months.^[18] The growth stages commence with eggs hatching into spiderlings after an incubation period of approximately 3 weeks. Juveniles then undergo multiple molts—typically 6 to 8 instars in total for the genus—during which their coloration shifts from pale yellow or orange in early stages to the characteristic red of adults.^[18] Adult maturation primarily occurs in late summer to autumn, with males maturing from late spring through fall in northern parts of the range.^[18] Mortality in P. cardinalis is primarily driven by predation from wasps such as Pompilidae and Sphecidae, as well as adverse weather conditions.^[18] Lifespans tend to be shorter in northern ranges due to colder temperatures limiting activity periods.^[19] The species follows a univoltine generational cycle, typically producing one generation per year in temperate zones, with immatures overwintering.^[30]