Cobitis feroniae, Novaga & Bellucci & Geiger & Freyhof, 2024

Novaga, Riccardo, Bellucci, Davide, Geiger, Matthias F. & Freyhof, Jörg, 2024, Cobitis feroniae, a new spined loach from southern Latium, Italy (Teleostei: Cobitidae), Zootaxa 5458 (3), pp. 385-402 : 389-396

Cobitis feroniae , sp. nov.

( Figs. 3–7 )

Holotype. ZFMK-ICH-133324 , 47 mm SL, male, Italy: Latium region: Latina prov.: Fosso del Moscarello at Latina , 41.508745, 12.836667.

Paratypes. ZFMK-ICH-133325–133353, 29, 40–72 mm SL; ZFMK-ICH-133406–133409, 2 males, 65–69 mm, 2 females, 45–47 mm; data same as holotype .

Other materials. ZFMK-ICH-098004, 1, 60 mm SL; Italy: Fosso San Magno at Via Portaturo, about 2 km south of Monte San Biagio, 41.3467, 13.3794 .— ZFMK-ICH-133354–133356, 3, 44–53 mm SL, Italy: Fiumetta spring at Terracina, 41.298134, 13.278767 .

New material used in molecular genetic analysis. FSJF-DNA 3646 , ( GenBank accession number: OR196720) ; FSJF-DNA 3648 , ( GenBank accession number: OR196711) ; FSJF-DNA 3649 , ( GenBank accession number: OR196708) ; FSJF-DNA 3650 , ( GenBank accession number: OR196709); Italy: Canale Imperiale at Nocera Inferiore, 40.779965, 14.632604 .— FSJF-DNA 4041 ; Italy: Fosso del Moscarello at Latina , 41.508745, 12.836667; (GenBank accession numbers: OR196710, OR196712–OR196718) .— FSJF-DNA 4042 ; Italy: Amaseno river at Prossedi, 41.502494, 13.252106 ; ( GenBank accession number: OR196719) .

Diagnosis. Cobiti s feroniae ( Figs. 3–7 ) is distinguished from C. zanandreai ( Fig. 8 ) and C. bilineata by having many, small, black dots below Z4 at least in individuals larger than 50 mm SL (vs. absent). These dots are found along a wide band between the pectoral-fin base and the caudal peduncle, and even on the belly in some individuals, while being restricted to a field above and in front of the anal-fin base in other individuals. In some individuals smaller than 50 mm SL, the black dots are absent. In all individuals of C. zanandreai and C. bilineata examined, these dots are absent, except for two, very large females of C. zanandreai (68, 80 mm SL), where few such dots are present between the pelvic- and anal-fin base. Cobiti s feroniae is further distinguished from C. zanandreai and C. bilineata by usually having a single, black spot at the upper caudal peduncle (vs. large black spots at upper and lower caudal peduncle in all C. bilineata ; very small spots at upper and lower caudal peduncle in most individuals in Volturno populations of C. zanandreai ; no spot on lower caudal peduncle in others; spots absent in Liri populations), and anterior to dorsal-fin origin, the pigmentation in Z2 separated from the pigmentation in Z1 (vs. pigmentation in both zones largely confluent in C. zanandreai ). Furthermore, blotches in Z4, below dorsal-fin base, are usually round or square-shaped (vs. horizontally elongated in the Volturno population of C. zanandreai ; elongated, rarely round or square-shaped in Liri population of C. zanandreai ). Cobiti s feroniae is further distinguished from C. bilineata by having black nares (vs. same colour as adjacent tissue). The black spots on caudal peduncle are small and often hardly visible in C. feroniae (and C. zanandreai ) (v s. large and clearly visible in C. bilineata ).

Description. See Figures 3–7 for general appearance and Table 3 for morphometric data of holotype and 20 paratypes.A small and deep-bodies species. Greatest body depth at or slightly anterior to dorsal-fin origin, decreasing towards caudal-fin base. Head profile slightly convex, head length 1.2–1.5 times in body depth. Snout blunt, 0.7–0.9 times in postorbital length. Interorbital space narrow, slightly convex. Eye diameter 0.2–0.4 times in head depth at eye, 15–19% HL, 0.9–1.9 times in interorbital width. Caudal peduncle 1.2–1.7 times longer than deep. No or a shallow hump at nape. Pelvic axillary lobe present, fully attached to body. Margin of dorsal and anal fins convex or straight. Caudal fin truncate or slightly rounded. A shallow ventral keel on caudal peduncle, dorsal keel absent. Pelvic-fin origin below 2 nd or 3 rd branched dorsal-fin ray. Largest recorded specimen 65 mm SL.

Dorsal fin with 7½(n=10) branched rays. Anal fin with 5½ (n=10) branched rays. Caudal fin with 7+7 (n=8), 8+7 (n=1), 8+8 (n=1) branched rays. Pectoral fin with 7 (n=9) and 8 (n=1) branched rays, and pelvic fin with 5 (n=3), and 6 (n=7) branched rays. Body completely covered by embedded scales, absent on belly and breast. Scales small. Focal area in subdorsal scales small, eccentric, with well-developed radii. Lateral line short, reaching middle or posterior end of pectoral fin. Suborbital spine bifurcate, reaching slightly beyond centre of eye. Lamina circularis roundish. Mouth small and arched. Lips thin, mental lobes of lower lip short, without furrows, usually well separated, not produced into a barbel-like process. Rostral barbel reaching base of mandibular barbel. Mandibular barbel reaching to, or slightly in front of vertical of nostril. Maxillary barbel reaching vertical of front border of eye.

Sexual dimorphism. Males have a longer pectoral fin and a lamina circularis on pectoral fin (vs. absent).

Colouration. Body pale yellowish or cream white (in preserved specimens) with a dark-brown or greyish pigmentation pattern organised in one mid–dorsal and four lateral zones (Z1–Z4). Head covered with small spots, often forming a vermiculated pattern. A narrow stripe running from tip of snout to eye, usually from nare to eye only. Mid-dorsal pigmentation consists of a series of 13–18 irregularly shaped, small to medium-sized blotches, 5–9 on predorsal back, usually one at dorsal-fin origin, one below dorsal-fin base, and 5–8 behind dorsal-fin base; some shaped as short saddles, a marbled pattern on back in front of dorsal-fin base in few individuals. Z2 about as wide as Z1 and Z3. Z1 with small, irregular and merged dots; pigmentation in Z1 usually reaching dorsally to interspaces of mid-dorsal blotches; pigmentation in Z1 reaching to dorsal-fin base, fused with pigmentation in Z2 and Z3 on postdorsal flank. Z2 with round or square-shaped blotches, well separated from each other, not forming stripes. Pigmentation in Z2 reaching to vertical of anus in some individuals, and reaching to caudal peduncle in others. Spots in Z3 small, irregular, forming a sand-like pattern in some females, larger in other females; forming a line of small blotches, restricted to one line, few isolated spots, or a narrow band in some males; reaching to vertical of dorsal-fin base in some individuals, especially in males, to caudal-fin base in large females. Z4 with a total of 13–17 large irregularly shaped blotches, round or vertically elongated in front of vertical of dorsal-fin base, larger, and often square-shaped or round behind. Blotches in Z4 not fused to each other. Pigmentations in Z1–Z4 forming a marmorate pattern on posterior part of caudal peduncle in some individuals. Many, small, black dots below Z4, in individuals larger than 50 mm SL; absent in few smaller individuals. Dots found along a wide band between pectoral-fin base and caudal peduncle, on belly in some individuals; restricted to a field above and in front of anal-fin base in other individuals. One small or minute, black, bold, round spot at upper caudal-fin base. Fins hyaline in life and in preserved individuals. Caudal fin with 3–4 and dorsal fin with 5–6 dark brown, sometimes irregularshaped bars. No pigmentation on paired fins. Barbels white.

Etymology. Named after the ancient Italic goddess Feronia, considered the tutelary deity of wilderness, water, springs, and wild animals. Feronia was particularly venerated in the Pontine marshes, where the remnants of her sanctuary along the Feronia springs are still visible. A noun in apposition.

Common name. Pontine spined loach (English), cobite pontino (Italian).

Distribution and Habitat. Cobitis feroniae has been recorded in the coastal watercourses and artificial channels flowing in the Pontine and the Fondi plains in the Latium region, where it inhabits all the main watercourses between the Astura catchment in the north (Pontine plain, province of Rome), and the Pedemontano channel in the south (Fondi plain, province of Latina ) ( Fig. 2 ). A disjointed and isolated population has also been found further south in the Sarno catchment of the Campania region (province of Salerno). Cobitis feroniae lives in spring-fed rivers and channels with slow flowing water and soft riverbed. It can also be found in small agricultural ditches connected to the main channels that are only seasonally flooded. Remarkably, the population of Fiumetta occurs in a very short (about 300 m) concrete channel fed by a coastal spring at Terracina (Latium region) with slightly brackish water (salinity 1,5 ppt; conductivity 2860 uS/cm). This channel is inhabited by the loaches up to 50 m from the sea mouth, together with Rutilus rubilio and Anguilla anguilla.

Remarks. The overlapping distribution of C. zanandreai and C. feroniae , raises compelling questions about their biogeography. The possibility of a recent human-mediated introduction of C. feroniae from Latium to the Sarno drainage (e. g. by use as live baits in angling) cannot be entirely ruled out, but it appears quite unlikely. In fact, these two areas are quite far from each other (about 200 km), heavily industrialized and cultivated, and there are only artificial canals with no particular interest for sport fishing activities. In addition, the use of loaches as live baits has been reported only from northern Italy, where it is used to capture predatory fishes such as Perca fluviatilis , Salmo marmoratus , Esox lucius and Micropterus nigricans , all of which are absent in the Sarno plain. The presence of C. zanandreai closer to the Sarno catchment (e.g. Volturno and Liri-Garigliano drainages) would also make this species an easier source of live baits for local anglers. Moreover, no fish stocking activities have been reported to occur from southern Latium to Campania, due to the consolidated use of aquaculture centres located in northern Italy ( Bianco 1995). All the populations of C. feroniae have been recorded within 20 km from the sea, along the springs that flow from the carbonatic chains of the Volsci mountains and the Sarno mountains ( Fig. 2 , red mark). Cobitis zanandreai has been recorded between the drainages of Liri-Garigliano and Volturno, which occupy the inland valleys situated between the axial chains of the Apennines to the north and the Volsci Range and the coastal chains of Campania to the South. We suspect that these two catchments share a common history, and were repeatedly connected and separated during the Pleistocene as a result of the emergence of the Roccamonfina volcano about 650,000 years BP ( Radicati di Brozolo et al. 1988, Rouchon et al. 2008), followed by the disappearance of the Lirino lake about 346,000 years BP ( Marra et al. 2021). The apparent absence of C. zanandreai in the main tributary of the Volturno, the river Calore Irpino ( Fig. 2 , in grey), appears quite difficult to explain, and can be a topic for further investigations. The observed genetic divergence of 2.9% (K2P distance) in the mitochondrial COI marker between C. feroniae and C. zanandreai does however imply a much earlier separation of the two populations. Based on previous studies, a rate of molecular divergence for the COI gene fragment is expected to lie between 0.4 % per Myr per lineage ( Perea et al. 2010), 0.9% ( Webb et al. 2004) or up to 1-2% ( Delrieu-Trottin et al. 2017) in different fish groups. The independent evolution of C. feroniae and C. zanandreai could thus have started already from 1.5–7.0 Mya, while the separation between C. ohridana (found in Albania, Montenegro and North Macedonia) and the C. zanandreai group has been estimated to have occurred around 6.5–7.4 Mya by Perdices et al. (2008). In this period, the Apennine orogeny proceeded gradually. It involved large areas of the Adriatic crust in the chain, thereby shifting the water divide eastward ( Mariotti & Doglioni 2000). During the initial compressional phase, this process uplifted catchments on the Adriatic slope, which later, due to the migration of extensional tectonics, lowered the western river catchments. The orogenic crest divides gradually migrated eastward, leading to the capture and shift of the drainage systems over the last 2.5 million years ( Lanari et al. 2023), possibly facilitating the isolation and subsequent migration of C. zanandreai and C. feroniae clades into the direction of the Thyrrenian coast. It is possible that the intense volcanic activity in this area (e.g. Latium Volcano, Roccamonfina, Phlegraean Fields and Somma-Vesuvio), together with the Quaternary development of the Volsci Range ( Cardello et al. 2020; 2021; Alessandri et al. 2021), also played a role in the isolation and current distribution of C. zanandreai and C. feroniae . The coastal area situated between Latium and Campania has also been recently identified as a region of high genetic diversity for the leuciscid fish Rutilus rubilio ( Petrosino et al. 2022; Petrosino et al. 2023), suggesting its relevance for the evolutionary history of Italian freshwater fishes.

Threats. Hybridization between C. zanandreai and C. bilineata has been hypothesized by Bianco & De Filippo (2011) as a possible threat to C. zanandreai , but never recorded with certainty. We obtained molecular evidence of hybridization between C. feroniae and C. bilineata in the Amaseno River (Latium region; Fig. 2 ). This drainage, situated in the Pontine plain, was inhabited only by C. feroniae in the 19th century, but during the second half of the 20 th century, following stocking activities with fishes from northern Italy, the alien C. bilineata was introduced and replaced the native species, becoming the only loach recorded in recent years ( Bellucci et al. 2021). The majority of the individuals currently collected at this site show the typical characters of C. bilineata : two well-defined black spots at caudal base (vs. single, small and hardly visible black spot at the upper caudal peduncle in C. feroniae ); blotches along Z4 not dissociated into irregularly shaped and set blotches at the caudal base (vs. dissociated and irregular spots often indistinguishable from those along Z2 and Z 3 in C. feroniae ); and absence of blackish nares (vs. blackish nares in C. feroniae ). Some individuals instead show slightly intermediate characters between C. bilineata and C. feroniae , such as many small, black dots below Z4, irregularly-shaped blotches at the end of Z4, and only one black spot at the caudal peduncle ( Fig. 9 ). Indeed, one of these atypical C. bilineata specimens analysed in this study was found to possess mtDNA of C. feroniae , suggesting the occurrence of a hybridization event ( Figs. 1–9 ). Further studies are required to assess the real extent of the admixture, which potentially poses a serious threat to C. feroniae , due to the almost complete artificial interconnection of the Pontine plain’s populations with the Amaseno River that has resulted from the land reclamation in the early 20 th century ( Kwan et al. 2014).

Moreover, the habitat of C. feroniae entirely consists of small, lowland rivers and channels that have undergone a strong anthropogenic influence. These watercourses depend on the karstic springs fed by groundwater, threatened by increasing extraction and climate change ( Panizzi et al. 2010). In this regard, we report the apparent extirpation of the population of the Pedemontano channel in the Fondi plain (Latium region). This concrete rectified channel, completely isolated from the surrounding hydrographic network, is fed by a few springs, which were completely dried out during the drought of 2017. After this event, no loaches have been found in the site despite repeated sampling, nor other freshwater species previously reported ( Rutilus rubilio and Squalius squalus ), with the exception of the alien Gambusia holbrooki . A sustainable management of the water resources seems therefore essential to guarantee the survival of this species.

The widespread hydraulic works performed in riverbeds can also damage and eventually destroy the soft-bottom microhabitat used by C. feroniae and C. zanandreai . Recently, the population of C. zanandreai in the Rio stream (Latium region) supposedly underwent local extinction after a hydraulic safety intervention carried out in 2022. Furthermore, water pollution reaches high levels in the entire range of C. feroniae , due to the intensive agricultural, zootechnical and industrial activities, combined with high demographic pressure and insufficient water treatment that characterize the Pontine and Fondi plains ( Gazzetti et al. 2010, Gazzetti et al. 2014). This is also true for some populations of C. zanandreai , especially along the Sacco valley, an area that suffered an environmental catastrophe due to contamination by beta-hexachlorocyclohexane and heavy metals between 1912 and 2008 ( Bernardini et al. 2013; Sala et al. 2012). Regarding the Sarno, levels of contamination are so dramatic that it is considered the most polluted river in Europe ( Cicchella et al. 2014), suggesting an uncertain future for the disjointed population of C. feroniae that inhabits this catchment. Lastly, all the recorded populations of C. feroniae (except one in the Ninfa River) are located outside protected areas or Natura 2000 sites, raising concerns about the long-term conservation of this localized endemic species.

Figures

FIGURE 1. Maximum likelihood estimation of the phylogenetic relationships of Cobitis species included in the Adriatic group by Perdices et al. (2008) and Buj et al. (2014). based on the mitochondrial COI barcode region (HKY model, discrete Gamma distribution for rate differences with 3 categories +G parameter = 0.1065). Nucleotide positions with less than 98% site coverage were eliminated, resulting in 450 analysed positions. Numbers of major nodes indicate bootstrap values from 1000 pseudoreplicates from the ML, NJ and MP method. Dashed bars right to the specimen labels indicate species demarcation results from the ASAP partitions. The tree is drawn to scale (except to the outgroup) with branch lengths depicting number of substitutions per site.

FIGURE 2. Records of Cobitis feroniae and C. zanandreai. Data based on personal collections and previous records (in literature) published by Cavicchioli (1965), Bruno (1983), and Maio (2012).

FIGURE 3. Cobitis feroniae, ZFMK-ICH-133324, holotype, 47 mm SL; Italy: Fosso del Moscarello at Latina.

FIGURE 4. Cobitis feroniae, ZFM-ICH-133406–ICH-133409, paratypes, from top: male, 45 mm SL; male, 47 mm SL; female, 65 mm SL; female, 69 mm SL; Italy: Fosso del Moscarello at Latina.

FIGURE 5. Cobitis feroniae, ZFMK-ICH-133324, holotype, 47 mm SL; Italy: Fosso del Moscarello at Latina, right side reversed.

FIGURE 6. Cobitis feroniae, ZFMK-ICH-133406–ICH-133409, paratypes, from top: female, 69 mm SL; female, 65 mm SL; male, 45 mm SL; male, 47 mm SL; Italy: Fosso del Moscarello at Latina, right side reversed.

FIGURE 7. Cobitis feroniae, from top, Italy: not preserved, female, 65 mm SL; not preserved, male, about 35 mm SL; Sarno at Nocera Inferiore; FSJF 4123, male, 53 mm SL; spring Fiumetta at Terracina.

FIGURE 8. Cobitis zanandreai, from top, Italy: ZFMK-ICH-133391, female, about 70 mm SL; ZFMK-ICH-133392, male, about 40 mm SL; Melfa at Roccasecca; not preserved, female, about 70 mm SL; Sacco at Olevano Romano; not preserved, female, about 60 mm SL; Vandra at Monteroduni.

FIGURE 9. Putative C. bilineata hybrids, from top, Italy: FSJF-DNA 4042, female, about 40 mm, hybrid between C. bilineata and C. feroniae; not preserved, female, about 60 mm; not preserved, female, about 70 mm; not preserved, female, about 70 mm; Amaseno river at Prossedi.

Tables

TABLE 3. Morphometric data of Cobitis feroniae (holotype, ZFMK-ICH-133324, paratypes, ZFMK-ICH-133325–

	holotype		holotype and paratypes
	male		females (n=10)			males (n=10)
		mean	min	max	SD	mean	min	max	SD
In percent of standard length
Head length	22	21.3	19.9	23.1	1.0	22.5	20.3	24.6	1.5
Body depth at dorsal fin origin	15	17.2	15.2	19.1	1.4	15.5	13.7	17.2	1.1
Caudal peduncle depth	11	10.6	9.8	12.1	0.8	10.5	9.2	11.6	0.7
Caudal peduncle length	15	15.6	14.7	16.3	0.5	14.7	13.5	16.8	1.1
Predorsal length	51	52.6	49.1	55.0	1.8	53.4	50.9	59.8	2.4
Postdorsal length	37	38.7	34.3	41.3	2.3	37.3	33.7	42.4	2.6
Prepelvic length	53	52.7	50.7	54.5	1.3	53.0	49.3	57.6	2.3

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