Gaziella, De Clerck & Schockaert, 1995

Diez, Yander L., Monnens, Marlies, Wuyts, Arlien, Brendonck, Luc, Reygel, Patrick, Schmidt-Rhaesa, Andreas & Artois, Tom, 2023, Taxonomy and phylogeny of Dalytyphloplanida Willems et al., 2006 (Platyhelminthes: Rhabdocoela), with the description of a new family, a new genus, and sixteen new species from Cuba and Panama, Organisms Diversity & Evolution (New York, N. Y.) 23 (4), pp. 631-681 : 670-671

Gaziella and Moevenbergia

The monophyly of the genus Gaziella is demonstrated after the inclusion of two new species in our phylogenetic analysis, which cluster together with a previously sequenced and undescribed species. All species of Gaziella share the diagnostic features of the genus as established by De Clerck and Schockaert (1995): the presence of a single seminal vesicle contained within the male copulatory bulb and an anterior proboscis-like and glandular invagination. Now five species of Gaziella are known, three of which are described in this contribution. The two previously known species, G. lacertosa De Clerck & Schockaert, 1995 and G. pileola De Clerck & Schockaert, 1995 , were described from the eastern coast of Africa ( Kenya, Western Indian Ocean) ( De Clerck & Schockaert, 1995). An unidentified species of Gaziella from the Mediterranean was included in the phylogenetic analysis of Van Steenkiste et al. (2013). Therefore, the known distribution of the genus is extended to the Caribbean and Atlantic coasts of Cuba.

A common characteristic of the three new species described from Cuba is the presence of two types of anterior rhabdite tracts. One type presents filiform rhabdites ( Fig. 7d : ar2) and in the other type the rhabdites are thicker ( Fig. 7d : ar1). The presence of different types of anterior rhabdite tracts was not mentioned in the description of the other two previously known species (see De Clerck & Schockaert, 1995). The general internal morphology of all species of Gaziella is similar and they mostly differ in the detailed morphology of the male copulatory bulb. Although the position of the pharynx is not a strong characteristic to differentiate among species of Gaziella , this structure is located at mid body ( G. pileola and G. microcirra sp. n.) or in the second body half ( G. lacertosa , G. cochleata sp. n., and G. glandulosa sp. n.).

Gaziella pileola is readily distinguished from its congeners by its very long cirrus (249–305 μm; x = 270 µm), which is smaller in the other four species: G. glandulosa sp. n. 94 μm, G. lacertosa 48–78 μm (x = 64 µm), G. cochleata sp. n. 26–54 μm (x = 44 µm), and G. microcirra sp. n. 33–51 μm (x = 41 µm). From these measurements, it is clear that also G. glandulosa sp. n. is well recognised by its cirrus length. Similarly, in both G. pileola and G. glandulosa sp. n. the sclerotised cap surrounds the most distal end of the cirrus (10% and 20% of its length, respectively). In G. cochleata sp. n. and G. microcirra sp. n., the sclerotised cap surrounds at least the distal 60% of the cirrus, whereas in G. lacertosa , it surrounds the distal 30%. A unique feature of G. glandulosa sp. n. is the fact that the proximal 80% of its cirrus is devoid of spines and shows thick glandular walls. In all other species of Gaziella , the cirrus is fully covered by spines.

Gaziella cochleata sp. n. is the only species of the genus where the distal cap of the copulatory bulb is a spiralised plate, a clear diagnostic feature of this species. Gaziella microcirra sp. n. exhibits a cirrus similar in morphology to that of G. lacertosa . However, the average length of the cirrus of G. lacertosa (64 µm) is larger than that of G. microcirra sp. n. (41 µm). Furthermore, a distinguishing feature of G. microcirra sp. n. is the fact that the walls of its cirrus are partially sclerotised and form distinct, lamellar-like structures (see Figs. 6g and 8e ).

Representatives of Moevenbergia Armonies & Hellwig, 1987 (formally Promesostomidae , Brinkmanniellinae ), are morphologically similar to Gaziella . These genera differ from each other by the presence of two extracapsular seminal vesicles and a pair of seminal reservoirs on each oviduct in Moevenbergia ( Armonies & Hellwig, 1987) , whereas there is a single intracapsular seminal vesicle and a single seminal reservoir on each oviduct in Gaziella ( De Clerck & Schockaert, 1995) . Recently, Armonies (2017) described a second species of Moevenbergia : M. oculofagi Armonies, 2017 . However, M. oculofagi exhibits two traits typical of Gaziella : the presence of a strong, anterior, proboscis-like structure and a single and well-developed, intracapsular seminal vesicle ( Armonies, 2017). Species of Moevenbergia do not have an anterior, proboscis-like structure ( Armonies & Hellwig, 1987).

Seminal receptacles were not observed in M. oculofagi , but the development of these structures depends on the reproductive state of the specimens and sometimes are not observable (i.e., when not filled with sperm). Therefore, we suggest M. oculofagi to be transferred to Gaziella (now G. oculofagi comb. n.). Gaziella oculofagi comb. n. is similar to G. microcirra sp. n.; however, the former has a smaller cirrus (x = 32 µm long) and does not exhibit the sclerotised lamellae in the cirrus characteristic for G. microcirra sp. n.

Following this reasoning, Gaziella now contains six species, three of which are described in this paper. Further molecular phylogenetic analyses are necessary to elucidate the relationships between Gaziella and Moevenbergia .

Figures

Fig. 7 Live specimens of spe- cies of Gaziella. a Gaziella cochleata sp. n. b–e G. microcirra sp. n. a, b Body organisation. c, d Details of the anterior region of the body and the rhabdite tracts. e Male copulatory bulb. a, b Structures oriented with the anterior end toward the top of the plate. c–e Structures oriented with the anterior end toward the right side of the plate

Fig.6 Species of Gaziella. a, b Gaziella cochleata sp. n. c, d G. glandulosa sp. n. e–g G. microcirra sp. n. a, c, e Body organisation (live animals). b, d, e, f Cirrus and sclerotised cap from the holotypes. Structures oriented with the anterior end toward the top of the plate

Fig. 8 Micrographs of the atrial organs of species of Gaziella, from the holotypes. a–c, Gaziella cochleata sp. n. d G. glandulosa sp. n. e, f G. microcirra sp. n. a–c, e–f Struc- tures oriented with the anterior end toward the top of the plate. d Structures oriented with the anterior end toward the left side of the plate