Difflugia alhadiqa Soler-Zamora, González-Miguéns and Lara, 2021
Diagnosis: The test is brownish-yellow, cylindrical (no lateral compression) and does not possess a differentiated neck. It is built of mineral particles, held together by an organic cement. The aperture is circular and surrounded by smaller mineral particles.
Dimensions: 25–33 µm breadth, 48–56 µm length, 13.18–24.56 µm aperture diameter (n = 6)
Ecology: Freshwater. Type locality: Dimly lit cave wall at 500 m from the entrance of the cave of the Hundidero in the municipality of Montejaque, Malaga, Spain.
Remarks: The round aperture of D. alhadiqa differs from the three-lobed aperture of Difflugia baculosa Schönborn, 1965. It resembles Difflugia glans Penard, 1902, but the dimensions of D. alhadiqa fall below the size range for these species; also, the collar of small particles surrounding the aperture is not as developed as in D. glans. Difflugia hiraethogii Ogden, 1983 has a much larger size and a slightly pyriform test, along with a well differentiated
neck, absent in our species. Difflugia lucida Penard, 1890 is only slightly larger, but has an ovoid shape and is laterally compressed while D. alhadiqa has a circular cross section. Moreover, the ultrastructure of the organic cement
in D. alhadiqa can be easily told apart from D. lucida. Difflugia masaruzii Van Oye, 1958, has a colorless test (vs. brown-yellowish in D. alhadiqa) and is larger in size. The size of Difflugia pristis Penard, 1902 has an ovoid form and the test has a glossy black color, both things differ from D. alhadiqa. Difflugia pule Penard, 1902 could also be confused but has also a well differentiated neck, absent in D. alhadiqa. The arctica variety of Difflugia stechlinensis Schönborn, 1966 has a hyaline test, sharply truncated in the oral part which differs clearly from D. alhadiqa; moreover, it has no collar. Difflugia stouti Ogden, 1983 differs from D. alhadiqa on its very small aperture and the absence of a collar. In Difflugia tenuis Penard, 1890 the fundus of the test is acuminate, sometimes even with a small horn, while D. alhadiqa has always a rounded fundus.