Telmatochromis salzburgeri, Indermaur & Schedel & Ronco, 2025

Indermaur, Adrian, Schedel, Frederic D. B. & Ronco, Fabrizia, 2025, Morphological diversity of the genus Telmatochromis from the Lake Tanganyika drainage with the description of a new riverine species and the generic reassignment of the Malagarasi River lamprologine, Journal of Fish Biology 106 (4), pp. 1214-1230 : 1220-1226

3.3 | Description of Telmatochromis salzburgeri

sp. nov.

urn:lsid:zoobank.org:act:27B9EF25-861B-4BA6-9927-CECC7BC667F6 .

Figure 5; Tables 2 and 3.

Based on available phylogenomic information and our analyses of multivariate morphological data, we here formally describe T. salzburgeri sp. nov., previously referred to as Telmatochromis sp. “lufubu” ( El Taher et al., 2021; Indermaur, 2014; Ronco et al., 2020, 2021; Schedel et al., 2019). The description is based on the type series (n = 19) and six additional non-type specimens (see Tables 2, 3, and S1).

3.3.1 | Holotype

NHB-6475 (one specimen, male, 4.2 cm SL; ex. UNIBAS-IC-USG9); Zambia, Northern Province, Lufubu drainage, Nsumbu National Park, lower Lufubu at Chomba village , 30 km above confluence with Lake Tanganyika , altitude 815 m, 8.6859, 30.5644; collectors :

A. Indermaur, F. Ronco, W. Salzburger, F.D.B. Schedel; collection date: October 1, 2021; deposited at the Natural History Museum Basel (Basel, Switzerland).

3.3.2 | Paratypes (n = 18, see Table S1)

NHB-6476, NHB-6477, NHB-6478, NHB-6479: (four specimens 4.0 – 4.8 cm SL; ex. UNIBAS-IC-USE2, UNIBAS-IC-USG8, UNIBAS-IC-USH1, UNIBAS-IC-USH2); deposited with the holotype; ZSM-PIS-044282 (six specimens 3.2 – 4.7 cm SL; ex. DRC-3146, DRC-3147, DRC-3195, DRC-3196, DRC-3197, DRC-3198), deposited at the SNSB-Bavarian State Collection of Zoology (Munich, Germany) ; SAIAB-246199 (two specimens 4.0 – 4.1 cm SL, ex. ZSM-PIS-044282- Nr 1-2), deposited at the South African Institute for Aquatic Biodiversity (Makhanda, South Africa) ; BMNH-2024.7.19.1 – 2 (two specimens 3.3 – 3.3 cm SL, ex. ZSM-PIS-044282- Nr 5-6), deposited at the British Museum of Natural History (London, UK) ; AMNH-281176 (two specimens 3.3 – 3.8 cm SL, ex. ZSM-PIS-044282- Nr 3-4), deposited at the American Museum of Natural History (New York, USA) ; BE_ RMCA _ Vert _2024.018.P.0001 and BE_ RMCA _ Vert _2024.018. P.0002 (two specimens 3.2 – 3.3 cm SL, ex. ZSM-PIS-044282- Nr 7-8), deposited at the Royal Museum for Central Africa (Tervuren, Belgium) . The four specimens deposited with the holotype in Basel were collected with the holotype; the other 14 type specimens are from Zambia, Northern Province, Lufubu drainage, lower Lufubu at Chomba village, 30 km above confluence with Lake Tanganyika, altitude 818 m, 8.686376, 30.563983; collectors: A. Indermaur and F.D.B. Schedel; collection date: October 30, 2015 .

3.3.3 | Differential diagnosis

Adult individuals of T. salzburgeri sp. nov. are distinguished from all other members of the genus Telmatochromis by the presence of a prominent orange stripe along the base of the dorsal fin, extending into the dorsal fin and over the dorsum (see Figure 5a,b). Additionally, T. salzburgeri sp. nov. differs from members of the T. vittatus complex (i.e., T. bifrenatus , T. brichardi , T. vittatus , and allies such as Telmatochromis sp. “longola”) and T. brachygnathus by having a larger head (26.96 – 30.08 vs. 20.4 – 26.65 HL%SL) and longer jaws (29.18 – 40.68 vs. 19.56 – 28.96 PML%HL; 38.82 – 46.26 vs. 22.04 – 35.6 LJL%HL; Figures 4 and S2; Table S3). It further differs from the members of the T. vittatus complex by a greater pre-dorsal and pre-pectoral distance (31.32 – 34.92 vs. 23.32 – 30.05 PDD%SL; 31.46 – 35.43 vs. 23.72 – 31.04 PPecD%SL) and a dorsal fin with fewer spines (18 – 19 vs. 20 – 22 DFS) and that ends more anteriorly (17 – 18 vs. 19 – 21 VDS; Figures 4, S2, and S3; Tables S3 and S4). Additionally, T. salzburgeri sp. nov. differs from all members of the T. temporalis complex (i.e., T. brachygnathus , T. dhonti , T. temporalis , and allies such as Telmatochromis sp. “shell”) mainly by a more slender body shape (21.05 – 25.69 vs. 26.71 – 32.45 BD%SL) and the relative size of the LPJ (26.46 – 28.26 vs. 28.37 – 32.92 PJS%HL; Figures 4 and S2; Table S3). Finally, T. salzburgeri sp. nov. can be distinguished from its new congener T. devosi comb. nov. based on the relative size of the LPJ (26.46 – 28.26 vs. 29.11 – 31.05 PJS%HL; Figures 4 and S2; Table S3) and a partial bi- and tricuspid dentition in the inner rows of the oral jaws (Figure 3).

3.3.4 | Description

An overview of all morphological measurements and meristic counts is provided in Tables 2 and 3. The maximum total length of wildcaught specimens was 4.8 cm (SL), but they tend to grow much larger in captivity (A.I. and F.D.B.S. personal observations). The species is relatively slender with a body depth of 21.05 – 25.69%SL and has a relatively large head, with a head length of 26.96 – 30.08%SL.

3.3.5 | Colouration

T. salzburgeri sp. nov. exhibits no obvious sexual color dimorphism. The base color in both sexes is light brown to beige and gray, often structured as a patchy pattern with varying shades of beige to black (Figure 5a,b). The body is countershaded with overall darker colors dorsally, fading to almost white in the ventral region. The flank scales have a darker brown posterior margin resulting in a reticulated pattern covering the entire body, which fades toward the head and ventrum. In some individuals, the scales with darker borders are distributed irregularly and form diagonal lines rather than the typical reticulated pattern. The diagonal lines are usually more prominent in the posterior parts of the flank and strongest toward the caudal peduncle. The dorsal head profile and snout region are covered with dark brown irregular but (bilaterally) symmetrical vermiculations. T. salzburgeri sp. nov. has a very prominent orange stripe along the dorsal-fin base extending into the dorsal fin and into the dorsum for a few millimeters. This stripe starts anteriorly at the origin of the dorsal fin, decreases in width posteriorly, and ends shortly after the incision of the last dorsal-fin ray (Figure 5a,b). Further, the species exhibits a prominent but thin dark brown to bright orange opercular stripe, which starts at the posterior margin of the orbit and ends at the posterior end of the opercule. The dorsal part of the pectoral-fin base is typically colored in the same orange as the dorsal stripe, and sometimes this color patch is connected to the opercular stripe.

The dorsal fin is transparent to opaque light brown fringed by a blue grayish stripe along the outer margin, and the dorsal-fin laplets are orange. The posterior part of the dorsal fin has evenly distributed blueish or grayish spots. Ventrally, the dorsal fin fades into the deep orange of the dorsal stripe mentioned earlier. The caudal fin is brownish transparent with a distal blue fringe and radiating blueish or grayish spots forming stripes that transition into light and dark bands toward the caudal peduncle. The blue fringe is often more prominent on the dorsal and ventral parts of the caudal fin. The anal fin is brownish with a similar pattern to the dorsal fin.

Type series (HT and PT) All measured specimens HT Mean SD Minimum Maximum n Mean SD Minimum Maximum n Standard length 4.2 3.9 0.5 3.2 4.8 19 4.0 0.5 3.2 4.8 22

% SL Body depth 24.7 23.6 1.2 21.1

Head length 27.7 28.8 0.8 27.0

Caudal peduncle length 11.5 11.4 0.5 10.4 Caudal peduncle depth 12.5 11.7 0.4 10.9

Pre-dorsal distance 32.5 33.5 0.9 31.3

Pre-pectoral distance 33.7 33.8 0.9 31.6

Pre-anal distance 64.0 64.5 0.7 63.4

Pre-pelvic distance 36.0 36.7 0.7 35.6

Last dorsal-spine length 14.9 14.3 0.7 13.3

Last anal-spine length 14.4 14.9 0.5 14.1 Dorsal-fin length 61.1 59.3 1.0 57.6

Anal-fin length 23.5 24.1 0.6 22.9

Abdominal vertebra length 33.8 32.6 0.7 30.5 Caudal vertebra length 36.4 36.5 0.6 35.7

% HL Eye diameter 31.8 30.4 1.7 28.0

Snout length 32.6 32.8 2.7 28.0

Premaxilla length 40.7 34.7 3.0 29.2

Premaxilla height 40.0 33.3 2.6 29.0

Lower jaw length 45.0 42.5 2.5 38.8

LPJ size NA 27.7 0.6 26.5

LPJ width (% PJS) NA 108.3 3.4 103.2 LPJ length (% PJS) NA 92.4 2.9 88.7

Relative horn length NA 31.5 3.6 25.8

Relative area of dentition NA 69.0 7.1 58.6

25.7 19 23.5 1.2 21.1 25.7 22

30.1 19 28.7 0.9 27.0 30.1 22

12.1 19 11.4 0.5 10.4 12.1 22

12.5 19 11.7 0.4 10.9 12.5 22

34.9 19 33.3 1.0 31.3 34.9 22

35.4 19 33.8 1.0 31.5 35.4 22

65.6 19 64.7 0.9 63.4 66.9 21

37.8 19 36.7 1.1 34.5 39.6 22

15.7 18 14.4 0.8 13.3 16.5 21

15.6 19 14.8 0.5 13.8 15.6 20

61.6 19 59.4 1.3 57.6 62.8 22

25.2 19 24.1 0.7 22.9 25.6 22

33.8 19 32.7 0.7 30.5 34.0 22

38.2 19 36.5 0.7 35.7 38.2 22

33.0 19 30.7 1.9 28.0 34.0 22

39.6 19 32.5 2.7 28.0 39.6 22

40.7 19 35.0 2.9 29.2 40.7 22

40.0 19 33.6 2.7 29.0 40.0 22

46.3 19 42.5 2.5 38.8 46.3 22

28.3 6 27.7 0.6 26.5 28.3 6

112.7 6 108.3 3.4 103.2 112.7 6

96.9 6 92.4 2.9 88.7 96.9 6

35.4 6 31.5 3.6 25.8 35.4 6

78.1 6 69.0 7.1 58.6 78.1 6

Note: Details of the measurements are provided in Figure S1.

Abbreviations: HL, head length; HT, holotype; LPJ, lower pharyngeal jaw; NA, not available; PJS, LPJ size; PT, paratype; SL, standard length .

The eyes have a silver gray to darker brown iris with an iridescent ring around the pupil. A second iridescent blue to turquoise stripe surrounds the eye in the posterior and ventral portions and bends down to the posterior edge of the maxilla anteriorly.

Some specimens show a distinctive dark brown to almost black body colouration, rendering the usual color patterns, including the blue and orange markings absent or only faintly visible (Figure 5a,b). From field observations (snorkeling), we speculate that this dark body colouration occurs in dominant territorial individuals and is only temporary. However, at this stage we cannot exclude that it is, in fact, a habitat-dependent dichromatism comparable to that observed in some members of the T. temporalis complex ( Keita & Kohda, 1995; Takahashi, 2019).

Juveniles are similarly colored to adult fish, but they are overall slightly darker with dark blotches on a beige brownish body. These blotches are more prominent along a wide mid-flank lateral band and often composed of several diagonal lines formed by the fringed scales. Further, the juvenile colouration is characterized by a brownto-black spot on the border of caudal peduncle and caudal fin (Figure 5a).

In preserved specimens (in 10% formalin and then stored in 70% ethanol for more than a year), the colouration is very similar to live colouration, but the specimens lose all of their orange and blueish markings, and the overall body colouration becomes dark brown with somewhat lighter brown to beige ventrally (Figure 5b).

3.3.6 | Squamation

The flanks above and below the lateral lines are covered with comparatively large, circular ctenoid scales. The anterior dorsal area of the flank above the lateral line is scaleless from the head, extending posteriorly to about a quarter of the dorsal-fin length. A short transition zone with very small ctenoid scales leads into the flank region and toward the lateral line. The snout and head are largely scaleless. However, some individuals have up to three cycloid to ctenoid scales of

Type series (HT and PT) All measured specimens

Median Distribution n Median Distribution n

Enlarged outer teeth upper jaw 6 5 (3); 6 (15)

Enlarged outer teeth lower jaw 5 4 (1); 5 (11); 6 (6)

Inner series of teeth upper jaw 2 2 (9); 3 (7)

Inner series of teeth lower jaw 3 2 (1); 3 (15)

Gill rakers on the lower arch 5 5 (15); 6 (3)

Gill rakers on the upper arch 4 3 (3); 4 (16)

Scales on operculum 1 0 (8); 1 (6); 2 (4); 3 (1)

Scales on horizontal line 32 31 (1); 32 (13); 33 (4); 34 (1)

Scales on upper lateral line 23 21 (1); 22 (7); 23 (4); 24 (5); 25

(2)

Scales on lower lateral line 8 6 (2); 7 (5); 8 (11); 9 (1)

Scales on lower lateral line pits 17 10, 12, 13, 14, 15 (1); 16, 17 (3);

18 (7); 21 (1) Circumpeduncular scales 16 15 (4); 16 (14); 17 (1)

Anal-fin spines 6 6 (12); 7 (7)

Anal-fin rays 7 7 (11); 8 (8)

Dorsal-fin spines 19 18 (3); 19 (16)

Dorsal-fin rays 8 8 (10); 9 (9)

Pectoral-fin rays 13 12 (9); 13 (10)

Upper procurrent caudal-fin 4 3 (1); 4 (18) rays

Lower procurrent caudal-fin 3 2 (1); 3 (18)

rays

Total caudal-fin rays 23 22 (2); 23 (17)

Vertebra of last dorsal-spine 18 17 (7); 18 (12)

pterygophore

Vertebra of last anal-spine 18 17 (1); 18 (13); 19 (5) pterygophore

Abdominal vertebrae 14 13 (1); 14 (18)

Caudal vertebrae 18 17 (2); 18 (16); 19 (1) 18 6 5 (3); 6 (21) 24

18 5 4 (1); 5 (12); 6 (11) 24

16 2 2 (14); 3 (8) 22

16 3 2 (3); 3 (19) 22

18 5 5 (19); 6 (5) 24

19 4 3 (4); 4 (21) 25

19 0 0 (14); 1 (6); 2 (4); 3 (1) 25

19 32 31 (1); 32 (18); 33 (5); 34 (1) 25

19 23 21 (2); 22 (10); 23 (6); 24 (5); 25 (2) 25

19 8 6 (2); 7 (5); 8 (14); 9 (4) 25

19 17 10, 12 (1); 13 (2); 14 (1); 15 (2); 16 (4); 17 (3); 24 18 (8); 21, 23 (1)

19 16 15 (5); 16 (19); 17 (1) 25

19 6 6 (16); 7 (9) 25

19 7 7 (14); 8 (11) 25

19 19 18 (3); 19 (22) 25

19 8 8 (14); 9 (11) 25

19 12 12 (13); 13 (11) 24

19 4 3 (1); 4 (24) 25

19 3 2 (1); 3 (23); 4 (1) 25

19 23 22 (2); 23 (22); 24 (1) 25

19 18 17 (8); 18 (17) 25

19 18 17 (2); 18 (17); 19 (6) 25

19 14 13 (1); 14 (24) 25

19 18 17 (2); 18 (22); 19 (1) 25

Note: The values recorded from the holotype are marked in bold. Details of the counted characters are provided in Table S2.

Abbreviations: HT, holotype; PT, paratype.

varying size and shape (small to medium and circular to oval) on the posterior portion of the operculum at the level of the eye. The chest area is also scaleless. The belly is covered with very small ctenoid to cycloid scales, transitioning into larger flank scales through a gradient of 1 – 2 rows of intermediately sized scales. The horizontal line counts 31 – 34 scales, whereas there are 15 – 17 scales around the caudal peduncle (Figure S3; Table 3). The upper lateral line contains 21 – 25 pored scales and runs posteriorly 1 – 3 scale rows below the last dorsal-fin spine. The lower lateral line has 6 – 9 pored scales and is anteriorly extended by a highly variable number of scales with apparent marks of superficial pit neuromasts (Figure S3; Table 3). The two lateral lines are vertically separated by two rows of scales. The anterior part of the caudal fin is covered with 3 – 4 vertical columns of small ctenoid scales, with the median scales being slightly larger. In some individuals, the central scale is pored as an extension of the lower lateral line. The scaled area of the caudal fin extends posteriorly with small cycloid and ovoid interradial scales, covering up to two-thirds of the caudal-fin length. All paired fins, as well as the dorsal and anal fins, lack any squamation.

3.3.7 | Fins

The dorsal fin has XVIII – XIX spines and 8 – 9 soft rays, where the first dorsal-fin spine is always the shortest. The dorsal-fin base measures between 57.6% and 62.8%SL. The anal fin has VI – VII spines of increasing length, and 7 – 8 soft rays. The anal-fin base ranges between 22.9% and 25.6% SL. The caudal fin is rounded to slightly truncated in larger individuals and is composed of 23 rays (16 principal caudal-fin rays and 6 – 8 procurrent rays). The pectoral fin is composed of 12 – 13 rays and is relatively short, not reaching the level of the anus. The pelvic fin has one short spine and five soft rays that increase in length, resulting in a relatively short and rounded pelvic-fin profile. In most individuals, the pelvic fin reaches beyond the anal opening but maximally reaches the middle of the anal-fin base.

3.3.8 | Axial skeleton

T. salzburgeri sp. nov. typically has a total of 32, rarely 31 or 33, vertebrae, with 13 – 14 abdominal and 17 – 19 caudal vertebrae (excluding urostyle element; Figure 5b; Table 3). The pterygiophore supporting the last dorsal-fin spine is inserted between the neural spines of the 17th and 18th or the 18th and 19th vertebrae (counted from anterior to posterior). The pterygiophore supporting the last anal-fin spine is usually inserted between the haemal spines of the 18th and 19th or the 19th and 20th vertebrae and rarely between the haemal spines of the 17th and 18th vertebrae (Figure 5b and Table 3). Further, a single pre-dorsal bone (i.e., supraneural bone) is present; and the hypurals 1 and 2 and hypurals 3 and 4 are fused into two seamless units.

3.3.9 | Jaws and dentition

The mouth is relatively large, terminal, and has isognathus jaws, with the posterior margin of the maxilla just reaching the anterior margin of the orbit (Figure 5b). The upper and lower jaws contain 5 – 6 and 4 – 6 conical, greatly enlarged, and widely spaced teeth, respectively (Figure 3; Table 3). Thereby the two outermost of the enlarged teeth are the largest (canines). All teeth in the outer row of upper and lower jaws are unicuspid with brown tips and a broad base. Posteriorly the teeth of the outer row steeply decrease in size. Both the upper and the lower jaws have 2 – 3 inner rows of very small teeth (Table 3). These inner teeth rows hold tri- and bicuspid teeth anteriorly and unicuspid teeth posteriorly.

3.3.10 | Gill rakers

The total gill raker count is 8 – 10, with 3 – 4 epibranchial and 5 – 6 ceratobranchial rakers (Table 3). The rakers are widely spaced, and the most anterior ceratobranchial rakers are very small, but increase in size toward the cartilaginous plug (joint). The raker at the joint is slightly shorter than the longest ceratobranchial raker, and the epibranchial gill rakers further decrease in size.

3.3.11 | Distribution and biology

T. salzburgeri sp. nov. is known only from two localities near Chomba village on the lower reaches of the Lufubu River, a direct affluent of southern Lake Tanganyika in northern Zambia (32 km upstream from the lake; Figures 1 and 6a). The species was neither found in the upper and middle reaches of the river system nor close to the river delta (Figure 6a). At the type locality (8.6859, 30.5644) the Lufubu River is about 15 m wide and, on average, about 1 – 2 m deep. Although T. salzburgeri sp. nov. is most abundant in deeper pools with moderate current (up to 4 m water depth), it can also be found in shallow riffle zones with high current (Figure 6b). In the shallow riffle zones the substrate consists of pebbles and larger rocks, whereas the deeper pools have a much higher proportion of sandy and silty substrate interspersed with different sized rocks, which are sometimes covered in thick layers of filamentous algae and Aufwuchs. The water temperature at the type locality varied between 23 C in July ( Indermaur, 2014; Schedel et al., 2018), 26.2 C in October (measured in 2021), and 28.1 C in November ( Indermaur, 2014; Schedel et al., 2018). The pH was between 6.8 and 7.5 ( Indermaur, 2014; Schedel et al., 2018), and the conductivity was 26 μS (measured in 2021).

T. salzburgeri sp. nov. is benthic, moderately rheophilic, and predominantly feeds on benthic invertebrates gathered between rocks and from the sand. The species is a biparental substrate spawner, which usually breeds in small caves excavated under and between larger rocks. In captivity, clutch sizes ranged between 30 and 50 eggs (A.I. and F.D.B.S. personal observations). At the type locality, T. salzburgeri sp. nov. co-occurs with other riverine cichlid species, such as Tilapia sparrmanii , Coptodon rendalli , Orthochromis indermauri , and the river ecotypes of Astatotilapia burtoni and Shuja horei ( Indermaur, 2014; Schedel et al., 2018; Theis et al., 2014).

3.3.12 | Etymology

The species is named in honor of our friend, colleague, and mentor Prof. Dr. Walter Salzburger for his contributions in advancing the field of evolutionary biology and, in particular, cichlid research in Lake Tanganyika. He has supported several projects and numerous field expeditions of all the authors with great enthusiasm, which led, among many other things, to the description of T. salzburgeri sp. nov.