The Herradra, Horseshoe, or Moorish Arch is the mainstay of buildings built during the Moorish occupation of Spain from 711AD to 1492AD.
It is interesting to note that what we call the Moorish Arch was actually "borrowed" from a Visigothic design. The Visigoths were in Spain from the 5th to the 8th century
San Juan de Banos
Palencia Spain ca. 600 A.D.
When the Moors were expelled from Spain many stayed behind, including stone masons. They were collectively known as Mudejar, and the style that the masons developed incorporated elements of both Christian and Moorish design.
Jesuit Mission Jesus de Tavaranque Paraguay
The current doorway at Espada is often referred to as Moorish in design, and although it does have elements of the Mudejar design, Tello's original was something quite different. The quatrefoil (see example below) is a design that has been associated with Christian church architecture for over one and one half millennia. The four lobes signify good luck (like a four leaf clover) and also are said to stand for the four apostles: Matthew, Mark, Luke, and John. An example of it's use as an arch can be seen in a Christian setting as early as the 5th century in Istanbul (see left side insert), a full 200 years before Islam was born.
By superimposing a square on a standard quatrefoil you get a design called a barbed quatrefoil. An early use of this design is in a baptismal font in the Crypt at the Cathedral at Speyer, Germany finished in 1100 AD (see right side insert). The design on the underside of the proposed original arch at Espada is basically a barbed quatrefoil cut horizontally in half. An extensive search of churches and mosques in Europe and Asia did not turn up a single example of that design being used as a doorway support arch. A vast majority of the examples of that use comes from Mexico with the earliest dating from the early to mid 18th century. Out of a total of 12 examples found so far, only half predate Tello's arrival in San Antonio. It's likely that he had seen the design at some point is his career and brought it with him. There is an example from a mission in Paraquay but it was built by the Jesuits in the 1760's, 20 years after Tello's departure from San Antonio.
What is unique about the design at Espada is that it is made in classic Roman Arch style, with a semicircular outer shape, multiple voussoirs (wedge shaped stones) and the signature keystone. The example from Paraguay uses the same technique but more than twice the number of voussoirs. Close examination of all of the other Barbed Quatrefoil Arch doorways show that the stone they are carved out of are of a more decorative nature than supportive and in some cases appear to be one large piece of stone.
At this point it appears likely that the Barbed Quatrefoil Doorway Arch originated in Mexico. A majority of the examples so far found come from the Mexican Baroque Era (1730's -1760's), but there are older examples. The design is both labor and talent intensive which might account for it's rarity and disappearance.
Same Doorway looking in.
Ex Convento Franciscano Quelcholac Puebla ca. 1753
Tello left San Antonio in late summer of 1744. Two years later a church building was begun by the Jesuits in Zacatecas Mexico, Tello's home town, that used the Quatrefoil Arch. When Antonio Tello would have been 54 years old, a Barbed Quatrefoil Arch entryway using the Roman (multi voussoir) design was executed at a Jesuit Mission in Paraquay.
ca. 1100 AD
It was noted by one of the visiting friars that Tello had carved out the stones for the doorway but that they were awaiting "fine carving"
Mission San Jose San Antonio TX ca.1768
Capilla del Cerrito Tepeyac Hill Mexico City ca. 1750
Below are examples of early uses of the Regular Quaterfoil Arch in Christian architecture.
Iglesia de la Compania de Jesus Cuzco, Peru ca. 1650
Notice large partial quatrefoil above main entrance.
St. John Stoudios Monastery
Istanbul ca. 462
Templo de la Imnaculada Concepcion del Salto de la Agua
Mexico City ca. 1750
Iglesia Nuestra Senora de la Salud
San Miguel de Allende ca.1735
The City of San Antonio has adopted the Barbed Quatrefoil as a marketing symbol.
It should be noted that some literature refers to these as Trefoil Arches or Trifoliated Arches. The second is more accurate because a true trefoil is a totally different design.
Basilica of St. Servatius
Maastrich, Netherlands ca. 1039