Synopsis of Xenotilapia Boulenger, 1899

Type species: Xenotilapia sima Boulenger, 1899

Distinctive characters:

In 1986 Max Poll outlined the following distinctive characters for the genus Xenotilapia, and at the same time separated the genera Enantiopus, Microdontochromis and Asprotilapia from Xenotilapia.

Xenotilapia sensu Poll 1986:

• Body is elongated, 3.5 – 5 times as long as high. The dorsal profile is convex with a steep head profile; the ventral profile nearly horizontal.
• Dorsal fin contains (12) 13-15 hard rays and (10-11) 12-14 (15) soft rays; anal fin with 3 hard rays and (7) 8-12 (13-14) soft rays.
• 34-40 ctenoid scales along the longitudinal line.
• Generally three lateral lines are present; the third lateral line, placed between the anal and caudal fin could be more or less developed, occasionally only visible on one side of the body.
• Mouth small and protracted, teeth arranged in 2-4 rows and generally unicuspid, occasionally with a tendency to be cuspid (Xenotilapia nigrolabiata). Outer row of teeth are a bit more conical and larger and situated horizontally at the edge of the lower jaw.
• Lower pharyngeal bone triangular covered with mainly unicuspid teeth, except at the back and center where the teeth are molar shaped.
• Ventral fins symmetric, the external rays are generally shorter than the internal rays. The fins are not filamentous.
• Total length 100-179 mm.

In his revision of Xenotilapia Tetsumi Takahashi showed via morphological analyses, that the criteria which the separation of the three genera Enantiopus, Asprotilapia and Microdontochromis was based upon overlapped with Xenotilapia, and that the latter would not be a monophyletic group if these three genera were not included again. The expanded concept of Xenotilapia sensu Takahashi is thus "characterized by having a unique infraorbital condition: four infraorbitals, in which the anteriormost bone bears four or five sensory pores and does not overlap the elongated second bone. The only exception found among the expanded Xenotilapia was the occurrence of six sensory pores on in one specimen of X. leptura" (Takahashi 2003).

Species currently included sensu Takahashi 2003:

Xenotilapia bathyphila Poll, 1956

Type locality:

Sumbu Bay, Zambia

Taxonomic history:

• Xenotilapia bathyphila Poll, 1956 – by Poll 1986
• Xenotilapia ochrogenys bathyphilus Poll, 1956

Synonyms:

None

Xenotilapia boulengeri (Poll, 1942)

Type locality:

Rumonge, Burundi.

Taxonomic history:

• Xenotilapia boulengeri (Poll, 1942) – by Poll 1951
• Enantiopus boulengeri Poll, 1942

Synonyms:

• Parectodus lestradei Poll, 1942
• Xenotilapia lestradei Poll, 1951
• Xenotilapia mater-familias Poll, 1943
• Xenotilapia materfamilias Poll, 1956

Xenotilapia burtoni Poll, 1951

Type locality:

Burton Bay, DR Congo (former Zaire).

Taxonomic history:

• Xenotilapia burtoni Poll, 1951 – by Poll 1986
• Xenotilapia longispinis burtoni Poll, 1951

Synonyms:

None

Xenotilapia caudafasciata Poll, 1951

Type locality:

Moba Bay, DR Congo (former Zaire).

Taxonomic history:

None

Synonyms:

None

Xenotilapia flavipinnis Poll, 1985

Type locality:

Ruziba, Burundi.

Taxonomic history:

None

Synonyms:

None

Xenotilapia leptura (Boulenger, 1901)

Type locality:

Msambu, Tanzania.

Taxonomic history:

• Xenotilapia leptura (Boulenger, 1901) – by Takahashi 2003
• Asprotilapia leptura Boulenger, 1901

Synonyms:

None

Xenotilapia longispinis Poll, 1951

Type locality:

Between the Ruzizi River and Bujumbura, Burundi

Taxonomic history:

None

Synonyms:

None

Xenotilapia melanogenys (Boulenger, 1898)

Type locality:

Moliro, DR Congo (former Zaire).

Taxonomic history:

• Xenotilapia melanogenys (Boulenger, 1898) – by Takahashi 2003
• Enantiopus melanogenys (Boulenger, 1898) – by Poll 1986
• Xenotilapia melanogenys (Boulenger, 1898) – by Poll 1951
• Enantiopus melanogenys (Boulenger, 1898) – by Boulenger 1906
• Ectodus melanogenys Boulenger, 1898

Synonyms:

• Ectodus longianalis Boulenger, 1899

Xenotilapia nasus De Vos & van den Audenaerde, 1995

Type locality:

Gitaza, Burundi

Taxonomic history:

None

Synonyms:

None

Xenotilapia nigrolabiata Poll, 1951

Type locality:

Msamba Bay, Tanzania

Taxonomic history:

None

Synonyms:

None

Xenotilapia ochrogenys (Boulenger, 1914)

Type locality:

Kilewa Bay, DR Congo (former Zaire)

Taxonomic history:

• Xenotilapia ochrogenys (Boulenger, 1914) – by Poll 1986
• Enantiopus ochrogenys Boulenger, 1914 – by Greenwood 1978
• Xenotilapia ochrogenys ochrogenys (Boulenger, 1914) – by Poll 1956
• Xenotilapia ochrogenys (Boulenger, 1914) – by Poll 1946
• Enantiopus ochrogenys Boulenger, 1914

Synonyms:

• Stappersia singularis Boulenger, 1914
• Stappersetta singularis Whitley, 1950

Xenotilapia ornatipinnis Boulenger, 1901

Type locality:

Kibwesi, Tanzania

Taxonomic history:

None

Synonyms:

None

Xenotilapia papilio Büscher, 1990

Type locality:

40 km south of Moba (Tembwe Deux), DR Congo (former Zaire).

Taxonomic history:

None

Synonyms:

None

Xenotilapia rotundventralis (Takahashi, Yanagisawa & Nakaya, 1997)

Type locality:

Nkumbula Island, Zambia.

Taxonomic history:

• Xenotilapia rotundiventralis (Takahashi, Yanagisawa & Nakaya, 1997) – by Takahashi 2003
• Microdontochromis rotundiventralis Takahashi, Yanagisawa & Nakaya, 1997

Synonyms:

None

Xenotilapia sima Boulenger, 1899

Type locality:

Moliro, DR Congo (former Zaire).

Taxonomic history:

None

Synonyms:

None

Xenotilapia tenuidentata Poll, 1951

Type locality:

Vua Bay, DR Congo (former Zaire).

Taxonomic history:

• Xenotilapia tenuidentata Poll 1951 – by Takahashi 2003
• Microdontochromis tenuidentatus (Poll, 1951) – by Poll 1986
• Xenotilapia tenuidentata Poll, 1951

Synonyms:

None

Remarks on taxonomic status:

As mentioned earlier Xenotilapia sensu Takahashi now encompasses the species in the former genera Enantiopus, Microdontochromis and Asprotilapia, a total of 17 species. Takahashi´s revision and the applicability of the expanded concept of Xenotilapia will be discussed in separate paper.

Takahashi´s expanded Xenotilapia equals Sturmbauer & Meyer´s Asprotilapia-clade, one of four major clades identified within the tribe Ectodini by molecular analyses (Sturmbauer & Meyer 1993). This has recently been confirmed by another molecular work, which has also shown that the clade underwent a major radiation immediately after its origin. Quite interestingly the analyses suggest that Xenotilapia sensu Takahashi is polyphyletic and therefore in need of a revision (Koblmüller et al. 2004). This topic will be addressed in a separate paper.