A new genus of Theraphosid spider from Mexico, with a particular palpal bulb structure (Araneae, Theraphosidae, Theraphosinae)

Magnacarina gen. nov. from Mexico is described. Hapalopus aldanus West, 2000 from Nayarit, is transferred to the new genus with an emended diagnosis creating the new combination Magnacarina aldana comb. nov. Three new species are described: Magnacarina moderata Locht, Mendoza & Medina sp. nov. from Nayarit and Sinaloa; Magnacarina primaverensis Mendoza & Locht sp. nov. and Magnacarina cancer Mendoza & Locht sp. nov., both from Jalisco. Magnacarina gen. nov. is characterized by an unusual bifid palpal bulb, and has a primary projection located in the central area of the palpal bulb and directed retrolaterally; this projection possesses the prolateral superior and retrolateral keels. Next to the primary projection is a secondary projection, which may be short or long, ending in the prolateral inferior and apical keel surrounding the sperm pore. This secondary projection may have prolateral accessory keels and is diagnosed by possessing a nodule of inwardly curled megaspines, located in the basal ventro-retrolateral region of metatarsi I in adult males. Additionally, male tibiae I possess three apophyses. Females of Magnacarina gen. nov. have a single reduced and strongly sclerotized spermatheca, with an apical lobe projecting ventrally, and with a uterus externus that is longer and wider than the spermatheca. European Journal of Taxonomy 232: 1–28 (2016) 2


Introduction
Mexico has the second highest number of formally described tarantula species worldwide, with 84 species (World Spider Catalog 2016).Despite this, Mexican theraphosid spiders have been poorly studied and it is common to find undescribed species and novel genera (Vol 1999(Vol , 2000(Vol , 2001;;Locht et al. 2005;Locht, 2008;Locht & Medina 2008;Mendoza 2012aMendoza , 2012bMendoza , 2014aMendoza , 2014b;;Schmidt 2012;Estrada-Alvarez 2014;Ortiz & Francke 2014).West (2000) described Hapalopus aldanus, a small theraphosid from Nayarit state in Mexico, which did not resemble any known theraphosid species.Due to the general shape of the male palpal bulb and female spermatheca, he placed that new species in the genus Hapalopus Ausserer, 1875.Unfortunately, he did not mention which characters linked the new species with Hapalopus.Locht (2008) investigated Hapalopus aldanus West, 2000 and determined the species did not belong to Hapalopus or any other known theraphosid genus.However, it was determined that this species belonged in the Theraphosinae due to the presence of urticating setae of the type III, the oval unipartite spermatheca, and the multiple keels on the male palpal bulb, which are the diagnostic features of this subfamily.Locht also indicated it might represent an undescribed genus because of the very distinctive shape of male palpal bulb.
After examining spider collections in the American Museum of Natural History (AMNH), the Colección Nacional de Arácnidos (CNAN) and the Laboratorio de Acarología Anita Hoffman (LAAH), we noticed more specimens with the same male palpal bulb morphology as in H. aldanus.Following confirmation that these specimens possessed the three tibial apophyses and cluster of megaspines in the basoretrolateral area of metatarsi I, as indicated by Locht (2008), it was determined that these specimens belonged to a new genus of subfamily Theraphosinae.Herein, we describe Magnacarina gen.nov.and three additional new species, transferring H. aldanus to represent the type species.Additionally, we propose new nomenclature for the unique features in the male palpal bulb morphology.

Diagnosis
Magnacarina gen.nov.differs from all other known theraphosine genera, except Bonnetina, in having three apophyses on male tibia I and a retrolateral nodule on metatarsus I. Males differ from Bonnetina in having a bifid palpal bulb that possesses a primary and secondary projections.Additionally, Magnacarina gen.nov.differs in possessing a retrolateral nodule of metatarsus I with megaspines, whereas Bonnetina has a granular one.Females differ in possessing a very low semicircular spermatheca with a uterus externus that is longer and wider than the Bonnetina triangular, domiform or digitiform spermatheca.Magnacarina gen.nov.has the following character combination: bifid shape of male palpal bulb with one sperm pore.It has a primary projection, located in the central area of palpal bulb and directed retrolaterally.This projection possesses the prolateral superior and retrolateral keels.).Following the primary projection is a secondary projection (long or short), ending with the prolateral inferior and apical keels surrounding the sperm pore.The prolateral inferior keel is always the widest distally.The secondary projection may have prolateral accessory keels that are variable in size and number.Males have a nodule of prolaterally curled megaspines, located at the basal ventroretrolateral region of metatarsi I (except for M. moderata sp.nov.).Male tibiae I with three apophyses.The accessory apophysis well to slightly developed, with apical spines variable in size and number.Urticating setae of the type III arranged in one dorsomedian patch.Females with very low spermatheca and single semicircular receptacle.Uterus externus always longer and wider than spermatheca.

Remarks
Adult males of Magnacarina gen.nov.have a retrolateral nodule of megaspines, located in the retrolaterobasal region of metatarsus I (except M. moderata sp.nov.).This nodule is considered homologous to the granular one found in Bonnetina, so it is possible that these genera are closely related.

Etymology
The genus gender is feminine, comprising magnus, a Latin adjective meaning "very large" or "great", and the Latin word carina, which means "keel".Generic name refers to the very large primary projection in the male palpal bulb (Figs 2D, 6D, 9D, 14D).

Distribution
Magnacarina gen.nov. is endemic to Mexico and only known from the states of Sinaloa, Nayarit and Jalisco.The genus inhabits the deciduous forest along the Pacific coast to the foothills of the Sierra Fig. 3. Magnacarina aldana (West, 2000).Madre Occidental.Specimens collected during fieldwork were found under rocks, in shallow burrows or superficial scrapes covered with silk.

Emended diagnosis
Magnacarina aldana comb.nov.males differ from M. cancer sp.nov. in possessing a thinner prolateral inferior keel that is distally rounded and oriented to the apex, and the retrolateral apophysis is thinner apically; females differ in possessing a wider spermatheca.Magnacarina aldana comb.nov.differs from M. primaverensis sp.nov. in possessing a highly developed accessory apophysis and a lower number of prolateral accessory keels as well as in the thinner prolateral inferior keel and the coloration of the carapace and legs in both sexes.Magnacarina aldana comb.nov.differs from M. moderata sp.nov. in that males have a retrolateral nodule of megaspines and females a medially longer spermatheca.
Magnacarina aldana comb.nov. is characterized by the following character combination: male palpal bulb with a prominent primary projection that is strongly curved retrolaterally (Fig. 2A); retrolateral and prolateral superior keels thin and well developed, posterior extension of prolateral superior keel ends on the back face (Fig. 2D-E); secondary projection possesses two prolateral accessory keels (Fig. 2B,  D).Prolateral inferior keel wide and increasing from posterior to apical (Fig. 2C-E).Apical keel well developed, covering the sperm pore that opens towards prolateral (Fig. 2D-E).Prolateral apophysis conical with one inner spine longer than its length (Fig. 1G-H); retrolateral apophysis strongly curved to dorsal (Fig. 1H-I); accessory apophysis slightly developed (Fig. 1G, I).Male palpal tibia retrolateral process short subconical, slightly developed on distal third (Fig. 1F).Spermatheca reduced and low, with one single semicircular, strongly sclerotized receptacle.Uterus externus is three times wider, and longer than the spermatheca (Fig. 3E-H).Variations summarized in Table 1.

Other material examined
MEXICO: 1 ♀, Nayarit, 8 km S. of Compostela, Jul. 1996, coll Variations of some quantitative characters in the specimens of the type series.Measurements in mm.Hyphens represent the interval between the lowest and highest value of each character.When left and right side values were taken, it was indicated as (left/right).

Distribution and natural history
Only known from the type locality.West (2000) mentioned that all specimens were collected in tropical deciduous forest while clearing land near cattle pastures.Males were found wandering during the daytime and females were found in shaded areas residing in scrapes under large rocks or fallen logs.He also indicated that the species is sympatric with Aphonopelma nayaritum (Chamberlin, 1940).

Diagnosis
Magnacarina cancer sp.nov.differs from all other Magnacarina species in the general shape of the male palpal bulb, with a prolateral inferior keel pointing to primary projection -resembling a crab claw.Secondary projection lacking prolateral accessory keels.Also M. cancer sp.nov.differs from other species in possessing a more developed accessory apophysis.Females differ in having a very reduced spermatheca.
Magnacarina cancer sp.nov.possesses the following character combination: male palpal bulb with a short primary projection, with distal half twisted to apical (Fig. 6A-C); retrolateral keel slightly developed; prolateral superior keel wide and well developed, posterior extension ends at the middle of prolateral face (Fig. 6D-E).Secondary projection short, lacking prolateral accessory keels (Fig. 6D).Prolateral inferior keel short and broader distally, apex acute and directed to Ppr -resembling a crab claw (Fig. 6A-B, E).Apical keel wide and covering the sperm pore (Fig. 6E).Accessory apophysis pointed dome shape and well developed (Fig. 5H).The retrolateral apophysis is thicker on distal half.The retrolateral nodule of megaspines very short and wide (Fig. 5F, I-J).Spermatheca very reduced, only a small rounded receptacle, as long as wide.Uterus externus is five times wider, and three times longer than the spermatheca (Fig. 7D).

Etymology
The specific epithet is in reference to the Latin word cancer (crab), describing the shape and orientation of the primary projection and apical keel that resembles a crab claw.

Distribution
The species is known only from the type locality in the Natural Protected Area of Chamela in Jalisco (Fig. 16).Specimens were collected in scrapes under medium size rocks and the males wandering during daytime.
Nothing is known about its life cycle or natural history.We know, however, that the same area is inhabited by Brachypelma klaasi (Schmidt & Krause, 1994), Bonnetina cyaneifemur Vol, 2000, and Aphonopelma sp., so it is possible there exists competition or even predation of M. cancer sp.nov.by these larger species.

Diagnosis
Magnacarina primaverensis sp.nov.differs from M. cancer sp.nov. in the general shape of the male palpal bulb, with prolateral inferior keel distally thinner and rounded, as well as in possessing prolateral accessory keels, and retrolateral apophysis slendering towards apex.Females differ in possessing a wider and longer spermatheca.M. primaverensis sp.nov.differs from M. aldana comb.nov. in possessing a slightly developed accessory apophysis; in a higher number of prolateral accessory keels, wider prolateral inferior keel and an inconspicuous male palpal tibia retrolateral process.Females differ in the endites posteriorly wider and rounded.Both sexes differ in a slightly orange carapace, with black cephalic area.M. primaverensis sp.nov.differs from M. moderata sp.nov. in having retrolateral nodule of megaspines, a male bulb with secondary projection shorter and thinner, with more prolateral accessory keels, and an inconspicuous male palpal tibia retrolateral process.Females differ in having a carapace as long as wide.
Magnacarina primaverensis sp.nov.has the following character combination: male palpal bulb with a prominent primary projection strongly curved retrolaterally; retroaleteral keel thin and well developed; prolateral superior keel well developed, posterior extension ends almost on the back face of palpal bulb (Fig. 9A-C); secondary projection with prolateral accessory keels, increasing in size from proximal to distal (Fig. 9C-D).Prolateral inferior keel wide, increasing from back to front and distal end slightly oriented to apical (Fig. 9A, C-D).Apical keel well developed, wider in the middle (Fig. 9D-E).Accessory apophysis barely developed, bearing large megaspines apically (Fig. 8E).Retrolateral nodule of megaspines with large spines, stout at base and slendering apically (Fig. 8I).Spermatheca reduced, low, with one single receptacle variable in shape, and strongly sclerotized.Uterus externus that is wider, and four to five times longer than the spermatheca (Fig. 11A-D).

Etymology
The specific epithet is a combination of the noun referring to the area that the species inhabits, "Bosque de la Primavera", and the Latin suffix -ensis, which means "of or from a place".

Color pattern
Color pattern of these spiders changes during their development.Spiderlings of M. primaverensis sp.nov.have a black carapace; the abdomen dorsum is dark with a central patch of urticating hairs.All the femora are black; patellae, tibia, metatarsi and tarsi are orange in color (2 nd to 6 th instar).In larger stadia, the carapace is dark brown with larger black cephalic area; the rest of the body remains as spiderling color (7 th to 8 th instar).As the individuals grow, the carapace becomes orange with black cephalic area; the abdomen dorsum develops a few red setae; palps and legs show dark blue iridescent color on femora, patellae becomes orange in color; and tibiae, metatarsi and tarsi become black (9 th instar onwards).This last coloration is stronger in adults, especially in males.Recently molted specimens have more vivid colors as observed in other theraphosids.In pre-molting individuals, colors are more opaque.

Distribution and natural history
Known only from the Natural Protected Area "Bosque de la Primavera", near Jalisco, México (Fig. 16).
All the spiders were found during daytime in a primary forest protected area.They live under rocks in shallow scrapes.The spiders are more difficult to find during the dry season.One of the females was found with a group of 25 spiderlings, with a legspan of 2.5 cm, suggesting that the spiderlings remain with the mother for a few months (Fig. 12C-D).Since there were no systematic collecting efforts to estimate the size of the population, the density of the distribution cannot be ascertained.The area is under increasing pressure from human activities of the nearby city of Guadalajara, and it is possible that the only existing population is in the protected area of "Bosque de la Primavera".

Diagnosis
Magnacarina moderata sp.nov.differs from all other Magnacarina species in lacking retrolateral nodule of megaspines and having only one prolateral accessory keel well developed.Magnacarina moderata sp.nov.also differs in possessing a secondary projection that is thinner and larger that of the other species, with a short and apically directed prolateral inferior keel.Females differ in carapace distinctly larger than wide.
Magnacarina moderata sp.nov.possesses the following character combination: male palpal bulb with a prominent primary projection strongly curved retrolaterally, with distal half slightly apically directed (Fig. A-C); retrolateral keel thin and slightly developed.Prolateral superior keel wide along its entire length, posterior extension ends almost in the middle of prolateral face (Fig. 14D-E); secondary projection is elongated and directed to apical, with one prolateral accessory keel well developed (Fig. 14C-D).
Prolateral inferior keel wide, divided in two sections, increasing from back to front and distal end oriented to apical (Fig. 14A-B, D).Apical keel well developed, wider distally.Sperm pore is located between prolateral inferior and apical keels (Fig. 14D-E).Accessory apophysis slightly developed, bearing large megaspines at the apex (Fig. 13G-H).Metatarsus I lacking retrolateral nodule of megaspines (Fig. 13H).Spermatheca reduced, low, with one single receptacle oval in shape, strongly sclerotized.Uterus externus is three times wider, and four to five times longer than the spermatheca (Fig. 15E-F).

Etymology
The specific epithet is the latinized version of "moderate", moderatus fem.moderata, referring to the shape of the secondary projection in the male palpal bulb which is moderately elongated and thinner than in other species.

Distribution
Known only from the border area between the states of Nayarit and Sinaloa (Fig. 16), this species inhabits scrapes under rocks in deciduous forest.West (2000) described Hapalopus aldanus and placed it in the genus, based on the shape of the male palpal bulb, the presence of a basoventral tubercle on metatarsus I, and the shape of the monolobed spermatheca.Unfortunately, he based his comparison with the male type of Hapalopus formosus (Ausserer, 1875) only on the illustrations by Gerschman & Schiapelli (1973) and suggested a continued study of male Hapalopus congeners.We have reviewed the material of all other known Mexican theraphosids with the type III urticating setae (i.e., Bonnetina, Cardiopelma, Davus and Schizopelma), and also the South American genera Cyriocosmus and Hapalopus for better comparison of morphological features.One of the most important challenges of this study was determining the homology of male palpal bulb keels and projections.The bulb of Magnacarina gen.nov. is characterized by two unique projections: a primary projection with PS and RK keels, and a secondary projection with PI and AK keels.As the PS and PI keel generally occur on the embolus only (Bertani 2000), it is considered that this new taxon has a bifid embolus.

Discussion
Although the position of the keels and their designation in bulbs of Bonnetina, Schizopelma, Davus and Cardiopelma seem to be clear and straightforward, in order to fit Magnacarina gen.nov.into this taxonomic scheme we must accept that the Ppr is an embolar projection formed by the fusion of PS and RK keels.Consequently, the Spr is extremely short, and a wide embolus carrying PI keel, AK keel and PAc keels in some cases.The male palpal bulb morphology in Bonnetina, Schizopelma, Davus and Cardiopelma is relatively congruent with this interpretation; additionally, the PI keel bears teeth (Bonnetina) or a developed subapical tooth (Schizopelma, Davus, Cardiopelma).A "ring-shaped" structure of PI and AK keels was observed in Cardiopelma, with the sperm pore between PI and AK keels, similar to that of Hapalopus; this corresponds with the position of the sperm pore in Magnacarina species, located between PI and A keels.Based on the morphological evidence, we consider our proposed homologies for keels is correct.Additionally, the naming of the new structures Ppr and Spr is necessary as nothing similar to these structures has been previously described.
of back face (as in M. primaverensis Mendoza & Locht sp.nov.), or extend only until the middle portion of the palpal bulb prolateral face (as in M. cancer Mendoza & Locht sp.nov.and M. moderata Locht, Mendoza & Medina sp.nov. The prolateral superior keel is large, extending posteriorly to palpal bulb back face.Posterior extension of the prolateral superior keel may extend to the palpal bulb back face (as in M. aldana comb.nov.), close to border

Table 2 .
Magnacarina primaverensisMendoza & Locht sp.nov.andMagnacarina moderata Locht,  Mendoza & Medina sp.nov.Variations of some quantitative characters in the specimens of the type series.Measurements in mm.Hyphens represents the interval between the lowest and highest value of each character.When left and right side values were taken, it was indicated as (left/right).